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  • Question 1 - Vitamin D is a group of secosteroids that play a role in calcium...

    Correct

    • Vitamin D is a group of secosteroids that play a role in calcium and phosphate control. Vitamin D's hormonally active metabolite is 1,25-dihydroxycholecalciferol.

      Which of the following actions of 1,25-dihydroxycholecalciferol is a direct action?

      Your Answer: Increases renal phosphate reabsorption

      Explanation:

      The hormone-active metabolite of vitamin D is 1,25-dihydroxycholecalciferol (commonly known as calcitriol). Its activities raise calcium and phosphate levels in the bloodstream.

      The following are the primary effects of 1,25-dihydroxycholecalciferol:

      Calcium and phosphate absorption in the small intestine is increased.
      Calcium reabsorption in the kidneys is increased.
      Increases phosphate reabsorption in the kidneys.
      Increases the action of osteoclastic bacteria (increasing calcium and phosphate resorption from bone)
      Inhibits the action of 1-alpha-hydroxylase in the kidneys (negative feedback)
      Thyroid hormone (parathyroid hormone) Calcium reabsorption in the tubules of the kidneys is increased, but renal phosphate reabsorption is decreased.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      54.1
      Seconds
  • Question 2 - A 70-year-old patient is diagnosed with Cushing's disease. She has a history of...

    Incorrect

    • A 70-year-old patient is diagnosed with Cushing's disease. She has a history of weight gain, hypertension, and easy bruising.

      In this patient, which of the following is the MOST LIKELY UNDERLYING CAUSE?

      Your Answer: Adrenal adenoma

      Correct Answer: Pituitary adenoma

      Explanation:

      Cushing’s syndrome is a collection of symptoms and signs caused by prolonged exposure to elevated levels of either endogenous or exogenous glucocorticoids.

      The most common cause of Cushing’s syndrome is the iatrogenic administration of corticosteroids. The second most common cause of Cushing’s syndrome is Cushing’s disease.

      Cushing’s disease should be distinguished from Cushing’s syndrome and refers to one specific cause of the syndrome, an adenoma of the pituitary gland that secretes large amounts of ACTH and, in turn, elevates cortisol levels. This patient has a diagnosis of Cushing’s disease, and this is, therefore, the underlying cause in this case.

      The endogenous causes of Cushing’s syndrome include:
      Pituitary adenoma (Cushing’s disease)
      Ectopic corticotropin syndrome, e.g. small cell carcinoma of the lung
      Adrenal hyperplasia
      Adrenal adenoma
      Adrenal carcinoma

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      58.2
      Seconds
  • Question 3 - A 59-year-old woman presents with a history of tiredness and weight gain and...

    Correct

    • A 59-year-old woman presents with a history of tiredness and weight gain and a diagnosis of hypothyroidism is suspected.

      Which of these changes is likely to appear first in primary hypothyroidism?

      Your Answer: Increased thyroid-stimulating hormone (TSH)

      Explanation:

      The earliest biochemical change seen in hypothyroidism is an increase in thyroid-stimulating hormone (TSH) levels.

      Triiodothyronine (T3) and thyroxine (T4) levels are normal in the early stages.

      TBG levels are generally unchanged in primary hypothyroidism.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      30.6
      Seconds
  • Question 4 - A 62-year-old woman presents with cold sensitivity, tiredness, and weight gain. A series...

    Incorrect

    • A 62-year-old woman presents with cold sensitivity, tiredness, and weight gain. A series of blood tests done shows a grossly elevated TSH level and a diagnosis of hypothyroidism is made.

      What is the commonest cause of hypothyroidism worldwide?

      Your Answer: Autoimmune thyroiditis

      Correct Answer: Iodine deficiency

      Explanation:

      Hypothyroidism occurs when there is a deficiency of circulating thyroid hormones. It is commoner in women and is most frequently seen in the age over 60.

      Iodine deficiency is the commonest cause of hypothyroidism worldwide.

      In developed countries, iodine deficiency is not a problem and autoimmune thyroiditis is the commonest cause.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      50.8
      Seconds
  • Question 5 - A patient is diagnosed as having a glucagonoma. Her blood serum glucagon concentration...

    Incorrect

    • A patient is diagnosed as having a glucagonoma. Her blood serum glucagon concentration is 1246 pg/mL.
      Glucagon INHIBITS which of the following processes? Select ONE answer only.

      Your Answer: Gluconeogenesis

      Correct Answer: Glycolysis

      Explanation:

      Glucagon is a peptide hormone that is produced and secreted by alpha cells of the islets of Langerhans, which are located in the endocrine portion of the pancreas. The main physiological role of glucagon is to stimulate hepatic glucose output, thereby leading to increases in glycaemia. It provides the major counter-regulatory mechanism to insulin in maintaining glucose homeostasis.
      Hypoglycaemia is the principal stimulus for the secretion of glucagon but may also be used as an antidote in beta-blocker overdose and in anaphylaxis in patients on beta-blockers that fail to respond to adrenaline.
      Glucagon then causes:
      Glycogenolysis
      Gluconeogenesis
      Lipolysis in adipose tissue
      The secretion of glucagon is also stimulated by:
      Adrenaline
      Cholecystokinin
      Arginine
      Alanine
      Acetylcholine
      The secretion of glucagon is inhibited by:
      Insulin
      Somatostatin
      Increased free fatty acids
      Increased urea production

      Glycolysis is the metabolic pathway that converts glucose into pyruvate. The free energy released by this process is used to form ATP and NADH. Glycolysis is inhibited by glucagon, and glycolysis and gluconeogenesis are reciprocally regulated so that when one cell pathway is activated, the other is inactive and vice versa.

      Glucagon has a minor effect of enhancing lipolysis in adipose tissue. Lipolysis is the breakdown of lipids and involves the hydrolysis of triglycerides into glycerol and free fatty acids. It makes fatty acids available for oxidation.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      53.4
      Seconds
  • Question 6 - A 33-year-old woman who is investigated for recurrent renal stones is discovered to...

    Incorrect

    • A 33-year-old woman who is investigated for recurrent renal stones is discovered to have a markedly elevated parathyroid hormone (PTH) level.
      Which of the following would stimulate PTH release under normal circumstances? Select ONE answer only.

      Your Answer: Decreased plasma calcitonin concentration

      Correct Answer: Decreased plasma calcium concentration

      Explanation:

      Parathyroid hormone (PTH) is a polypeptide containing 84 amino acids. It is the principal controller of free calcium in the body.
      PTH is synthesised by and released from the chief cells of the four parathyroid glands that are located immediately behind the thyroid gland.
      PTH is released in response to the following stimuli:
      Decreased plasma calcium concentration
      Increased plasma phosphate concentration (indirectly by binding to plasma calcium and reducing the calcium concentration)
      PTH release is inhibited by the following factors:
      Normal/increased plasma calcium concentration
      Hypomagnesaemia
      The main actions of PTH are:
      Increases plasma calcium concentration
      Decreases plasma phosphate concentration
      Increases osteoclastic activity (increasing calcium and phosphate resorption from bone)
      Increases renal tubular reabsorption of calcium
      Decreases renal phosphate reabsorption
      Increases renal conversion of 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol (via stimulation of 1-alpha hydroxylase)
      Increases calcium and phosphate absorption in the small intestine (indirectly via increased 1,25-dihydroxycholecalciferol)

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      50.2
      Seconds
  • Question 7 - A patient is diagnosed as having a glucagonoma. Her blood serum glucagon concentration...

    Correct

    • A patient is diagnosed as having a glucagonoma. Her blood serum glucagon concentration is 1246 pg/mL.
      Glucagon is produced in which of the following cells? Select ONE answer only.

      Your Answer: Alpha-cells in the pancreas

      Explanation:

      Glucagon is a peptide hormone that is produced and secreted by alpha cells of the islets of Langerhans, which are located in the endocrine portion of the pancreas. The main physiological role of glucagon is to stimulate hepatic glucose output, thereby leading to increases in glycaemia. It provides the major counter-regulatory mechanism to insulin in maintaining glucose homeostasis.
      Hypoglycaemia is the principal stimulus for the secretion of glucagon but may also be used as an antidote in beta-blocker overdose and in anaphylaxis in patients on beta-blockers that fail to respond to adrenaline.
      Glucagon then causes:
      Glycogenolysis
      Gluconeogenesis
      Lipolysis in adipose tissue
      The secretion of glucagon is also stimulated by:
      Adrenaline
      Cholecystokinin
      Arginine
      Alanine
      Acetylcholine
      The secretion of glucagon is inhibited by:
      Insulin
      Somatostatin
      Increased free fatty acids
      Increased urea production

      Glycolysis is the metabolic pathway that converts glucose into pyruvate. The free energy released by this process is used to form ATP and NADH. Glycolysis is inhibited by glucagon, and glycolysis and gluconeogenesis are reciprocally regulated so that when one cell pathway is activated, the other is inactive and vice versa.

      Glucagon has a minor effect of enhancing lipolysis in adipose tissue. Lipolysis is the breakdown of lipids and involves the hydrolysis of triglycerides into glycerol and free fatty acids. It makes fatty acids available for oxidation.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      29
      Seconds
  • Question 8 - Insulin binds to the insulin receptor (IR) on cell surfaces to exert its...

    Incorrect

    • Insulin binds to the insulin receptor (IR) on cell surfaces to exert its action. The IR is a very specific transmembrane receptor belonging to the tyrosine kinase receptor class.

      One of these also activates the IR:

      Your Answer: Somatostatin

      Correct Answer: IGF-I

      Explanation:

      Insulin receptor (IR), in addition to being activated by insulin, is also activated by IGF-I and IGF-II.

      The IR is a dimer with two identical subunits spanning the cell membrane and are connected by a single disulphide bond. The two sub-units include: The alpha chain situated on the exterior of the cell membrane and the beta chain spanning the cell membrane in a single segment.

      When insulin is detected, the alpha chains move together folding around the insulin making the beta chains move together, converting them into an active tyrosine kinase. This initiates a phosphorylation cascade increasing the expression of GLUT4 and allowing uptake of glucose by cells.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      46.5
      Seconds
  • Question 9 - A 71-year-old patient has been diagnosed with a dopamine-secreting neuroendocrine tumour.

    Which of the...

    Incorrect

    • A 71-year-old patient has been diagnosed with a dopamine-secreting neuroendocrine tumour.

      Which of the following statements about dopamine is correct?

      Your Answer: It is a peptide hormone

      Correct Answer: It inhibits prolactin release from the anterior pituitary

      Explanation:

      Dopamine is a neurotransmitter and amine hormone that is derived from the amino acid tyrosine. It is made in a number of places throughout the human body, both inside and outside the central nervous system. The adrenal medulla, dopamine neurons in the arcuate nucleus of the hypothalamus, the substantia nigra, and other areas of the brain produce dopamine.

      The tuberoinfundibular pathway refers to the dopamine neurons in the arcuate nucleus of the hypothalamus’ tubeal region. Dopamine is discharged into the hypothalamo-hypophyseal portal system from these neurons’ neurosecretory terminals at the median eminence.

      The major function of dopamine produced from the hypothalamus is to suppress prolactin production from the anterior pituitary, and it is released in reaction to excessive levels of prolactin secretion. Modulation of motor-control centres and activation of reward centres are two more crucial activities of the brain.
      Dopamine-secreting cells can also be found in other areas of the body, where they perform mostly paracrine functions (acting on nearby cells).

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      68.5
      Seconds
  • Question 10 - A 70-year-old patient diagnosed with Cushing's syndrome and has a history of weight...

    Incorrect

    • A 70-year-old patient diagnosed with Cushing's syndrome and has a history of weight gain, hypertension, and easy bruising.

      Which of these assertions about Cushing's syndrome is correct?

      Your Answer: The commonest cause is an adenoma of the pituitary gland

      Correct Answer: Diagnosis can be confirmed by a dexamethasone suppression test

      Explanation:

      Cushing’s syndrome is a group of symptoms and signs brought on by long-term exposure to high amounts of endogenous or exogenous glucocorticoids.

      Iatrogenic corticosteroid injection is the most prevalent cause of Cushing’s syndrome. Cushing’s illness is the second most prevalent cause of Cushing’s syndrome. Cushing’s disease is distinct from Cushing’s syndrome in that it refers to a single cause of the illness, a pituitary adenoma that secretes high quantities of ACTH, which raises cortisol levels.

      Because cortisol enhances the vasoconstrictive impact of endogenous adrenaline, patients with Cushing’s syndrome are usually hypertensive.

      Hyperglycaemia (due to insulin resistance) rather than hypoglycaemia is a common symptom.
      Cortisol levels fluctuate throughout the day, with the greatest levels occurring around 0900 hours and the lowest occurring at 2400 hrs during sleep. The diurnal swing of cortisol levels is lost in Cushing’s syndrome, and levels are greater throughout the 24-hour period. In the morning, levels may be normal, but they may be high at night-time, when they are generally repressed.

      A dexamethasone suppression test or a 24-hour urine free cortisol collection can both be used to establish the existence of Cushing’s syndrome.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      35.7
      Seconds
  • Question 11 - A 50-year-old man, known hypertensive on amlodipine has been visiting his GP with...

    Correct

    • A 50-year-old man, known hypertensive on amlodipine has been visiting his GP with symptoms of headache, tiredness, and muscle weakness. His blood test today shows a low potassium level of 2.8 mmol/L, and a slightly raised sodium level at 147 mmol/L.

      What is the MOST LIKELY diagnosis?

      Your Answer: Conn’s syndrome

      Explanation:

      When there are excessive levels of aldosterone independent of the renin-angiotensin aldosterone axis, primary hyperaldosteronism occurs. Secondary hyperaldosteronism occurs due to high renin levels.

      Causes of primary hyperaldosteronism include:
      Conn’s syndrome
      Adrenal hyperplasia
      Adrenal cancer
      Familial aldosteronism

      Causes of secondary hyperaldosteronism include:
      Renal vasoconstriction
      Oedematous disorders
      Drugs – diuretics
      Obstructive renal artery disease

      Although patients are usually asymptomatic, when clinical features are present, classically hyperaldosteronism presents with:
      Hypokalaemia
      Sodium levels can be normal or slightly raised
      Hypertension
      Metabolic alkalosis
      Less common, clinical features are:
      Lethargy
      Headaches
      Intermittent paraesthesia
      Polyuria and polydipsia
      Muscle weakness (from persistent hypokalaemia)
      Tetany and paralysis (rare)

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      37.6
      Seconds
  • Question 12 - Osteoclasts are a type of bone cell that are critical in the maintenance,...

    Incorrect

    • Osteoclasts are a type of bone cell that are critical in the maintenance, repair and remodelling of bones.
      Which of the following inhibits osteoclast activity? Select ONE answer only.

      Your Answer: Thyroxine

      Correct Answer: Calcitonin

      Explanation:

      Osteoclasts are a type of bone cell that breaks down bone tissue. This is a critical function in the maintenance, repair and remodelling of bones. The osteoclast disassembles and digests the composite of hydrated protein and minerals at a molecular level by secreting acid and collagenase. This process is known as bone resorption and also helps to regulate the plasma calcium concentration.
      Osteoclastic activity is controlled by a number of hormones:
      1,25-dihydroxycholecalciferol increases osteoclastic activity
      Parathyroid hormone increases osteoclastic activity
      Calcitonin inhibits osteoclastic activity
      Bisphosphonates are a class of drug that slow down and prevent bone damage. They are osteoclast inhibitors.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      40
      Seconds
  • Question 13 - A 58-year-old woman presents with symptoms of increase in weight, proximal muscular weakening...

    Incorrect

    • A 58-year-old woman presents with symptoms of increase in weight, proximal muscular weakening and withering, easy bruising, and acne. You notice that she has a full, plethoric aspect to her face, as well as significant supraclavicular fat pads, when you examine her. She has previously been diagnosed with Cushing's syndrome.

      Cushing's syndrome is most commonly caused by which of the following?

      Your Answer: Pituitary adenoma

      Correct Answer: Iatrogenic administration of corticosteroids

      Explanation:

      Cushing’s syndrome is a group of symptoms and signs brought on by long-term exposure to high amounts of endogenous or exogenous glucocorticoids. Cushing’s syndrome affects about 10-15 persons per million, and it is more common in those who have had a history of obesity, hypertension, or diabetes.

      Iatrogenic corticosteroid injection is the most prevalent cause of Cushing’s syndrome. Cushing’s illness is the second most prevalent cause of Cushing’s syndrome. Cushing’s disease is distinct from Cushing’s syndrome in that it refers to a single cause of the illness, a pituitary adenoma that secretes high quantities of ACTH, which raises cortisol levels.

      Cushing’s syndrome has several endogenous sources, including:
      Cushing’s disease is caused by a pituitary adenoma.
      Adrenal adenoma Ectopic corticotropin syndrome, e.g. small cell cancer of the lung
      Adrenal carcinoma is a cancer of the adrenal gland.
      Hyperplasia of the adrenal glands

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      88.3
      Seconds
  • Question 14 - A thyroid function test is done for a 55-year-old woman with non-specific symptoms,...

    Correct

    • A thyroid function test is done for a 55-year-old woman with non-specific symptoms, the results are shown below:
      TSH = 5.2
      Free T4 is normal
      Free T3 is normal

      The most likely diagnosis in this patient is?

      Your Answer: Subclinical hypothyroidism

      Explanation:

      Hypothyroidism is diagnosed using the results of thyroid function tests (TFTs).

      In the early stages of the disease, the earliest biochemical change noticed is a rise in thyroid-stimulating hormone (TSH) levels. Free triiodothyronine (T3) and thyroxine (T4) levels are usually normal.

      In primary hypothyroidism, the serum TSH level is usually greater than 10 mU/L, and free T4 levels are below the reference range.

      Subclinical hypothyroidism is diagnosed when the serum TSH level is above the reference range, and the free T4 levels are within the reference range. The test should, however, be repeated after 3-6 months to exclude transient causes of raised TSH.

      In summary, how to interpret TFTs in cases of suspected hypothyroidism is shown below:

      Subclinical hypothyroidism
      TSH is raised
      Free T4 is normal
      Free T3 is normal

      Primary hypothyroidism
      TSH is raised
      Free T4 is lowered
      Free T3 is lowered or normal

      Secondary hypothyroidism
      TSH is lowered or normal
      Free T4 is lowered
      Free T3 is lowered or normal

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      39.5
      Seconds
  • Question 15 - Which of these increases osteoclast activity? ...

    Correct

    • Which of these increases osteoclast activity?

      Your Answer: Parathyroid hormone

      Explanation:

      Osteoclasts are bone cell that break down bone tissue.

      Parathyroid hormone increases osteoclastic activity.

      1,25-dihydroxycholecalciferol increases osteoclastic activity

      Calcitonin inhibits osteoclastic activity

      Bisphosphonates are osteoclast inhibitors.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      34.3
      Seconds
  • Question 16 - A patient in the Emergency Department had a diagnosis of diabetic ketoacidosis (DKA)...

    Incorrect

    • A patient in the Emergency Department had a diagnosis of diabetic ketoacidosis (DKA) and you commence an insulin infusion.

      Which of these statements concerning insulin is true?

      Your Answer: Proinsulin is converted to insulin by the removal of a single peptide from the N-terminus

      Correct Answer: Insulin has a short half-life of around 5-10 minutes

      Explanation:

      Insulin, a peptide hormone, is produced in the pancreas by the beta-cells of the islets of Langerhans.

      The beta-cells first synthesise an inactive precursor called preproinsulin which is converted to proinsulin by signal peptidases, which remove a signal peptide from the N-terminus.

      Proinsulin is converted to insulin by the removal of the C-peptide.

      Insulin has a short half-life in the circulation of about 5-10 minutes.
      Glucagon and parasympathetic stimulation stimulates insulin release.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      54.4
      Seconds
  • Question 17 - A 59-year-old man presents with increased sweating, weight loss, and palpitations. A...

    Correct

    • A 59-year-old man presents with increased sweating, weight loss, and palpitations. A series of blood tests done found a very low TSH level and a diagnosis of hyperthyroidism is made.

      What is the commonest cause of hyperthyroidism?

      Your Answer: Graves’ disease

      Explanation:

      Hyperthyroidism results from an excess of circulating thyroid hormones. It is commoner in women, and incidence increases with age.

      Hyperthyroidism can be subclassified into:
      Primary hyperthyroidism – the thyroid gland itself is affected
      Secondary hyperthyroidism – the thyroid gland is stimulated by excessive circulating thyroid-stimulating hormone (TSH).

      Graves’ disease is the most common cause of hyperthyroidism (estimates are that it causes between 50 and 80% of all cases).

      Although toxic multinodular goitre, thyroiditis,TSH-secreting pituitary adenoma and drug-induced hyperthyroidism also causes hyperthyroidism, the commonest cause is Graves’ disease.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      36.9
      Seconds
  • Question 18 - A 54-year-old woman has been visiting her GP with symptoms of tiredness, muscle...

    Incorrect

    • A 54-year-old woman has been visiting her GP with symptoms of tiredness, muscle weakness and headaches. She is known to be hypertensive and takes amlodipine to control this. Her blood results today show that her potassium level is low at 3.0 mmol/L, and her sodium level is slightly elevated at 146 mmol/L.
      Which of the following is the SINGLE most appropriate INITIAL investigation?

      Your Answer: Selective adrenal venous sampling

      Correct Answer: Plasma renin and aldosterone levels

      Explanation:

      Primary hyperaldosteronism occurs when there are excessive levels of aldosterone independent of the renin-angiotensin axis. Secondary hyperaldosteronism occurs due to high renin levels.
      The causes of primary hyperaldosteronism include:
      Adrenal adenoma (Conn’s syndrome) – the most common cause of hyperaldosteronism (,80% of all cases). These are usually unilateral and solitary and are more common in women.
      Adrenal hyperplasia – this accounts for ,15% of all cases. Usually, bilateral adrenal hyperplasia (BAH) but can be unilateral rarely. More common in men than women.
      Adrenal cancer – a rare diagnosis but essential not to miss
      Familial aldosteronism – a rare group of inherited conditions affecting the adrenal glands
      The causes of secondary hyperaldosteronism include:
      Drugs – diuretics
      Obstructive renal artery disease – renal artery stenosis and atheroma
      Renal vasoconstriction – occurs in accelerated hypertension
      Oedematous disorders – heart failure, cirrhosis and nephrotic syndrome
      Patients are often asymptomatic. When clinical features are present, the classically described presentation of hyperaldosteronism is with:
      Hypertension
      Hypokalaemia
      Metabolic alkalosis
      Sodium levels can be normal or slightly raised
      Other, less common, clinical features include:
      Lethargy
      Headaches
      Muscle weakness (from persistent hypokalaemia)
      Polyuria and polydipsia
      Intermittent paraesthesia
      Tetany and paralysis (rare)
      Often the earliest sign of hyperaldosteronism is from aberrant urea and electrolytes showing hypokalaemia and mild hypernatraemia. If the patient is taking diuretics, and the diagnosis is suspected, these should be repeated after the patient has taken off diuretics.
      If the diagnosis is suspected, plasma renin and aldosterone levels should be checked. Low renin and high aldosterone levels (with a raised aldosterone: renin ratio) is suggestive of primary aldosteronism.
      If the renin: aldosterone ratio is high, then the effect of posture on renin, aldosterone and cortisol can be investigated to provide further information about the underlying cause of primary hyperaldosteronism. Levels should be measured lying at 9 am and standing at noon:
      If aldosterone and cortisol levels fall on standing, this is suggestive of an ACTH dependent cause, e.g. adrenal adenoma (Conn’s syndrome)
      If aldosterone levels rise and cortisol levels fall on standing, this is suggestive of an angiotensin-II dependent cause, e.g. BAH
      Other investigations that can help to distinguish between an adrenal adenoma and adrenal hyperplasia include:
      CT scan
      MRI scan
      Selective adrenal venous sampling

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      56.2
      Seconds
  • Question 19 - A 59-year-old otherwise well woman presents with a history of polydipsia and...

    Correct

    • A 59-year-old otherwise well woman presents with a history of polydipsia and polyuria. There is a past history of kidney stones, and blood tests done reveal the following:

      Na: 147 mmol/L (135-147 mmol/L)
      K: 4.0 mmol/L (3.5-5.5 mmol/L)
      Urea: 7.3 mmol/L (2.0-6.6 mmol/L)
      Creatinine: 126 mmol/L (75-125 mmol/L)
      Fasting blood glucose: 5.0 mmol/L (3.4-5.5 mmol/L)
      Corrected calcium: 3.21 mmol/L (2.05-2.60 mmol/L)
      Phosphate: 0.70 mmol/L (0.8-1.4 mmol/L)
      Parathyroid hormone: 189 ng/L (10-60 ng/L)

      The most likely diagnosis is?

      Your Answer: Primary hyperparathyroidism

      Explanation:

      ​Primary hyperparathyroidism the commonest cause of hypercalcaemia. It is commonest in women aged 50 to 60.
      The commonest cause of primary hyperparathyroidism is a solitary adenoma of the parathyroid gland (approximately 85% of cases).

      Primary hyperparathyroidism may present with features of hypercalcaemia such as polyuria, polydipsia, renal stones, bone and joint pain, constipation, and psychiatric disorders.

      In primary Hyperparathyroidism:
      PTH is elevated
      Calcium is elevated
      Phosphate is lowered

      In secondary Hyperparathyroidism:
      PTH is elevated
      Calcium is low or low-normal
      Phosphate is raised in CRF

      In tertiary Hyperparathyroidism:
      PTH is elevated
      Calcium is elevated
      Phosphate is lowered in CRF

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      257.6
      Seconds
  • Question 20 - You review an 83-year-old woman who has stage 5 chronic kidney disease. She...

    Incorrect

    • You review an 83-year-old woman who has stage 5 chronic kidney disease. She has a number of electrolyte problems.
      Which ONE of the following decreases the renal reabsorption of phosphate?

      Your Answer: Vasopressin

      Correct Answer: Parathyroid hormone

      Explanation:

      Parathyroid hormone (PTH) is a polypeptide containing 84 amino acids. It is the principal controller of free calcium in the body.
      The main actions of parathyroid hormone are:
      Increases plasma calcium concentration
      Decreases plasma phosphate concentration
      Increases osteoclastic activity (increasing calcium and phosphate resorption from bone)
      Increases renal tubular reabsorption of calcium
      Decreases renal phosphate reabsorption
      Increases renal conversion of 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol (via stimulation of 1-alpha hydroxylase)
      Increases calcium and phosphate absorption in the small intestine (indirectly via increased 1,25-dihydroxycholecalciferol)

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      29.3
      Seconds
  • Question 21 - A 38-year-old woman is investigated for Addison's disease. She had low blood pressure,...

    Incorrect

    • A 38-year-old woman is investigated for Addison's disease. She had low blood pressure, weakness, weight loss, and skin discoloration. An adrenocorticotropic hormone (ACTH) stimulation test is scheduled as part of her treatment.

      Which of the following statements about ACTH is correct?

      Your Answer: It is produced in the hypothalamus

      Correct Answer: It is released in response to the release of CRH

      Explanation:

      The anterior pituitary gland produces and secretes a peptide hormone called adrenocorticotropic hormone (ACTH) (adenohypophysis). It is secreted in response to the hypothalamus’s secretion of the hormone corticotropin-releasing hormone (CRH).

      ACTH promotes cortisol secretion via binding to cell surface ACTH receptors in the zona fasciculata of the adrenal cortex.

      ACTH also promotes the production of beta-endorphin, which is a precursor to melanocyte-releasing hormone (MRH).

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      1.5
      Seconds
  • Question 22 - A patient presents with a necrolytic migratory rash. Her blood serum glucagon concentration...

    Incorrect

    • A patient presents with a necrolytic migratory rash. Her blood serum glucagon concentration is 1246 pg/mL. Following further investigations, she is diagnosed with glucagonoma.
      Which SINGLE statement regarding glucagon is true?

      Your Answer: It stimulates glycolysis

      Correct Answer: It makes fatty acids available for oxidation

      Explanation:

      Glucagon is a peptide hormone that is produced and secreted by alpha cells of the islets of Langerhans, which are located in the endocrine portion of the pancreas. The main physiological role of glucagon is to stimulate hepatic glucose output, thereby leading to increases in glycaemia. It provides the major counter-regulatory mechanism to insulin in maintaining glucose homeostasis.
      Hypoglycaemia is the principal stimulus for the secretion of glucagon but may also be used as an antidote in beta-blocker overdose and in anaphylaxis in patients on beta-blockers that fail to respond to adrenaline.
      Glucagon then causes:
      Glycogenolysis
      Gluconeogenesis
      Lipolysis in adipose tissue
      The secretion of glucagon is also stimulated by:
      Adrenaline
      Cholecystokinin
      Arginine
      Alanine
      Acetylcholine
      The secretion of glucagon is inhibited by:
      Insulin
      Somatostatin
      Increased free fatty acids
      Increased urea production

      Glycolysis is the metabolic pathway that converts glucose into pyruvate. The free energy released by this process is used to form ATP and NADH. Glycolysis is inhibited by glucagon, and glycolysis and gluconeogenesis are reciprocally regulated so that when one cell pathway is activated, the other is inactive and vice versa.

      Glucagon has a minor effect of enhancing lipolysis in adipose tissue. Lipolysis is the breakdown of lipids and involves the hydrolysis of triglycerides into glycerol and free fatty acids. It makes fatty acids available for oxidation.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      44.7
      Seconds
  • Question 23 - A 39-year-old woman is feeling unwell one week after a parathyroid surgery.

    Which of...

    Correct

    • A 39-year-old woman is feeling unwell one week after a parathyroid surgery.

      Which of the following stimulates release of parathyroid hormone (PTH)?

      Your Answer: Increased plasma phosphate concentration

      Explanation:

      PTH is synthesised and released from the chief cells of the four parathyroid glands located behind the thyroid gland.
      It is a polypeptide containing 84 amino acids and it controls free calcium in the body.

      The following stimuli causes release of PTH:
      Increased plasma phosphate concentration
      Decreased plasma calcium concentration

      PTH release is inhibited by:
      Normal or increased plasma calcium concentration
      Hypomagnesaemia

      The main actions of PTH are:
      Increases plasma calcium concentration
      Decreases plasma phosphate concentration
      Increases osteoclastic activity (increasing calcium and phosphate resorption from bone)
      Increases renal tubular reabsorption of calcium
      Decreases renal phosphate reabsorption
      Increases renal conversion of 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol (via stimulation of 1-alpha hydroxylase)
      Increases calcium and phosphate absorption in the small intestine (indirectly via increased 1,25-dihydroxycholecalciferol)

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      28
      Seconds
  • Question 24 - Insulin is a very important peptide hormone produced by the islets of Langerhans...

    Correct

    • Insulin is a very important peptide hormone produced by the islets of Langerhans in the pancreas.
      Insulin is synthesised by which of the following cell types within the islets of Langerhans? Select ONE answer only.

      Your Answer: Beta cells

      Explanation:

      Insulin is produced by beta cells, located centrally within the islets of Langerhans, in the endocrine tissues of the pancreas. Insulin is a polypeptide hormone consisting of two short chains (A and B) linked by disulphide bonds. Proinsulin is synthesised as a single-chain peptide. Within storage granules, a connecting peptide (C peptide) is removed by proteases to yield insulin. Insulin release is stimulated initially during eating by the parasympathetic nervous system and gut hormones such as secretin, but most output is driven by the rise in plasma glucose concentration that occurs after a meal. The effects of insulin are mediated by the receptor tyrosine kinase.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      15.7
      Seconds
  • Question 25 - Vitamin D is a group of secosteroids that play a role in calcium...

    Correct

    • Vitamin D is a group of secosteroids that play a role in calcium and phosphate control. Vitamin D's hormonally active metabolite is 1,25-dihydroxycholecalciferol.

      Which enzyme hydroxylates 25-hydroxycholecalciferol to form 1,25-dihydroxycholecalciferol?

      Your Answer: 1-alpha-hydroxylase

      Explanation:

      The hormone-active metabolite of vitamin D is 1,25-dihydroxycholecalciferol (commonly known as calcitriol). Its activities raise calcium and phosphate levels in the bloodstream.

      In the presence of UVB light, 7-dehydrocholesterol is converted to cholecalciferol in the epidermal layer of the skin, resulting in 1,25-dihydroxycholecalciferol.

      Cholecalciferol is then converted to 25-hydroxycholecalciferol in the endoplasmic reticulum of liver hepatocytes by 25-hydroxylase (calcifediol).

      Finally, 1-alpha-hydroxylase converts 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol in the kidney. The key regulatory point in the formation of 1,25-dihydroxycholecalciferol is 1-alpha-hydroxylase, which is induced by parathyroid hormone or hypophosphatemia.

      The following are the primary effects of 1,25-dihydroxycholecalciferol:
      Calcium and phosphate absorption in the small intestine is increased.
      Calcium reabsorption in the kidneys is increased.
      Increases phosphate reabsorption in the kidneys.
      Increases the action of osteoclastic bacteria (increasing calcium and phosphate resorption from bone)
      Inhibits the action of 1-alpha-hydroxylase in the kidneys (negative feedback)

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      32.8
      Seconds
  • Question 26 - A 58-year-old man showing symptoms of increase in weight, proximal muscular weakening and...

    Correct

    • A 58-year-old man showing symptoms of increase in weight, proximal muscular weakening and withering, easy bruising, and acne. You notice that he has a full, plethoric aspect to his face, as well as significant supraclavicular fat pads, when you examine him. His blood pressure is 158/942 mmHg, and his glucose tolerance has lately been impaired. His potassium level is 3.2 mmol/L.

      What is the MOST LIKELY diagnosis?

      Your Answer: Cushing’s syndrome

      Explanation:

      Cushing’s syndrome is a group of symptoms and signs brought on by long-term exposure to high amounts of endogenous or exogenous glucocorticoids. Cushing’s syndrome affects about 10-15 persons per million, and it is more common in those who have had a history of obesity, hypertension, or diabetes.

      Cushing’s syndrome has a wide range of clinical manifestations that are dependent on the degree of cortisol overproduction. The appearance might be vague and the diagnosis difficult to detect when cortisol levels are just somewhat elevated. On the other hand, in long-term cases of severely increased cortisol levels, the presentation might be colourful and the diagnosis simple.

      Cushing’s syndrome has the following clinical features:
      Obesity and weight growth in the true sense
      Supraclavicular fat pads are fat pads that are located above the clavicle.
      Buffalo hump
      Fullness and plethora of the face (‘moon facies’)
      Muscle atrophy and weakening at the proximal level
      Diabetes mellitus, also known as impaired glucose tolerance
      Hypertension
      Skin thinning and bruising
      Depression
      Hirsutism
      Acne
      Osteoporosis
      Amenorrhoea or oligomenorrhoea

      Cortisol levels fluctuate throughout the day, with the greatest levels occurring around 0900 hours and the lowest occurring at 2400 hrs during sleep. The diurnal swing of cortisol levels is lost in Cushing’s syndrome, and levels are greater during the whole 24-hour period. In the morning, levels may be normal, but they may be high at night-time, when they are generally repressed. As a result, random cortisol testing is not an effective screening technique and is not advised.

      The following are the two most common first-line screening tests:
      Cortisol levels in the urine are measured every 24 hours.
      A diagnosis of Cushing’s syndrome can be made if more than two collections measure cortisol excretion more than three times the upper limit of normal.
      Physical stress (e.g., excessive exercise, trauma), mental stress (e.g., sadness), alcohol or drug misuse, complex diabetes, and pregnancy can all cause false positives.
      Renal dysfunction, inadequate collection, and cyclical Cushing’s disease can all cause false negatives.
      The overnight low-dose dexamethasone suppression test (LDDST) involves giving 1 mg of dexamethasone at 11 p.m. and measuring blood cortisol levels at 8 a.m. the next day.
      Cushing’s syndrome is diagnosed when cortisol is not suppressed to less than 50 nmol/L.
      It might be difficult to tell the difference between mild Cushing’s disease and normal cortisol production.
      False positives can occur as a result of depression, severe systemic sickness, renal failure, prolonged alcohol misuse, old age, and the use of hepatic enzyme-inducing medicines, among other things.
      False negatives are extremely uncommon in Cushing’s disease patients.

      A characteristic biochemical picture might also be helpful in confirming the diagnosis of Cushing’s syndrome. The following are the primary characteristics:
      Hypokalaemia
      Alkalosis metabolique

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      39.3
      Seconds
  • Question 27 - You examine a 48-year-old patient who has had proximal weakness, hypertension, and easy...

    Incorrect

    • You examine a 48-year-old patient who has had proximal weakness, hypertension, and easy bruising in the past. She exhibits considerable face fullness and truncal obesity on examination. You diagnose her�with Cushing's syndrome.
      When would her random cortisol level likely be abnormal?

      Your Answer: 0900 hrs

      Correct Answer: 2400 hrs

      Explanation:

      Cortisol levels fluctuate throughout the day, with the greatest levels occurring around 0900 hours and the lowest occurring at 2400 hrs during sleep.

      The diurnal swing of cortisol levels is lost in Cushing’s syndrome, and levels are greater throughout the 24-hour period. In the morning, levels may be normal, but they may be high at night-time, when they are generally repressed.

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      59.5
      Seconds
  • Question 28 - A 50-year-old man presents with headaches, lethargy, hypertension, and electrolyte disturbance. A...

    Incorrect

    • A 50-year-old man presents with headaches, lethargy, hypertension, and electrolyte disturbance. A diagnosis of primary hyperaldosteronism is made.

      Which biochemical pictures would best support this diagnosis?

      Your Answer: Hyperkalaemic metabolic acidosis

      Correct Answer: Hypokalaemic metabolic alkalosis

      Explanation:

      When there are excessive levels of aldosterone outside of the renin-angiotensin axis, primary hyperaldosteronism occurs. High renin levels will lead to secondary hyperaldosteronism.

      The classical presentation of hyperaldosteronism when symptoms are present include:
      Hypokalaemia
      Metabolic alkalosis
      Hypertension
      Normal or slightly raised sodium levels

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      46.8
      Seconds
  • Question 29 - A 30-year-old woman with type 1 diabetes mellitus is brought in drowsy and...

    Correct

    • A 30-year-old woman with type 1 diabetes mellitus is brought in drowsy and confused. Her BM is 2.2 mmol/l and a dose of IM glucagon is administered.

      What is the principal stimulus for the secretion of glucagon?

      Your Answer: Hypoglycaemia

      Explanation:

      Glucagon, a peptide hormone, is produced and secreted by alpha cells of the islets of Langerhans, located in the endocrine portion of the pancreas.

      Its main physiological role is stimulation of hepatic glucose output leading to increase in blood glucose. It is the major counter-regulatory hormone to insulin in maintaining glucose homeostasis.

      The principal stimulus for the secretion of glucagon is hypoglycaemia. Hypoglycaemia then stimulates:
      Glycogenolysis
      Gluconeogenesis
      Lipolysis in adipose tissue leading to increased glycaemia.

      Secretion of glucagon is also stimulated by arginine, alanine, adrenaline, acetylcholine and cholecystokinin

      Secretion of glucagon is inhibited by:
      Insulin
      Somatostatin
      Increased free fatty acids
      Increased urea production

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      33.1
      Seconds
  • Question 30 - A 36-year-old woman is 22-weeks pregnant and is investigated for a possible thyroid...

    Correct

    • A 36-year-old woman is 22-weeks pregnant and is investigated for a possible thyroid disorder. When her total thyroid hormone levels does not correlate with her thyrometabolic status, her thyroid-binding globulin levels are checked.

      What percentage of circulating thyroid hormones is bound to thyroid-binding globulin?

      Your Answer: 70%

      Explanation:

      Only a very small fraction of the thyroid hormones circulating in the blood are free. The majority is bound to transport proteins. Only the free thyroid hormones are biologically active, and measurement of total thyroid hormone levels can be misleading.

      The relative percentages of bound and unbound thyroid hormones are:
      Bound to thyroid-binding globulin -70%
      Bound to albumin -15-20%
      Bound to transthyretin -10-15%
      Free T3 -0.3%
      Free T4 -0.03%

    • This question is part of the following fields:

      • Endocrine Physiology
      • Physiology
      39.8
      Seconds

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Endocrine Physiology (14/30) 47%
Physiology (14/30) 47%
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