The most appropriate intervention in this patient is intravenous hydroxocobalamin.
The clinical scenario provided is suggestive of acute cyanide toxicity secondary to burning plastics in the house fire.
Cyanide ions inhibit mitochondrial cytochrome oxidase, preventing aerobic respiration. This manifests in normal oxygen saturations, a high pO2 and flushing (or ‘brick red’ skin) brought on by the excess oxygenation of venous blood. In the question above it is important to note that the blood gas sample given is venous rather than arterial. His blood gas also demonstrates an increased anion gap, consistent with his high lactate (generated by anaerobic respiration due to the inability to use available oxygen).

The recommended treatment for moderate cyanide toxicity in the UK is one of three options: sodium thiosulfate, hydroxocobalamin or dicobalt edetate.

Among the options given is hydroxocobalamin and this is, therefore, the correct answer. Hydroxocobalamin additionally has the best side-effect profile and speed of onset compared with other treatments for cyanide poisoning.

Other options:
– Intubation would be appropriate treatment in the context of airway burns but this patient has no evidence of these, although close monitoring would be advised.
– High-flow oxygen is the treatment for carbon monoxide poisoning – a sensible differential, but this man’s very high lactate and high venous pO2 fit better with cyanide toxicity. Intravenous dexamethasone would be another treatment for airway oedema once an endotracheal tube had been placed.
– Intravenous sodium nitroprusside is a treatment for high blood pressure that can cause cyanide poisoning, and would, therefore, be inappropriate.

Note:

Cyanide may be used in insecticides, photograph development and the production of certain metals. Toxicity results from reversible inhibition of cellular oxidizing enzymes
Clinical presentation:
Classical features: brick-red skin, the smell of bitter almonds
Acute: hypoxia, hypotension, headache, confusion
Chronic: ataxia, peripheral neuropathy, dermatitis

Management:
Supportive measures: 100% oxygen
Definitive: hydroxocobalamin (intravenously), also a combination of amyl nitrite (inhaled), sodium nitrite (intravenously), and sodium thiosulfate (intravenously).

Scabies is an infection caused by a microscopic mite known as Sarcoptes scabies. The chief presenting complaint is itching especially in skin folds and mostly during night. It spreads from one person to another through skin contact, and therefore it is more prevalent in crowded areas like hospitals, hostels and even at homes where people live in close contact with each other. Treatment options include benzyl benzoate, ivermectin, sulphur and permethrin.

Screening for cervical carcinoma helps to prevent the development of the disease. According to NICE, the screening interval using liquid-based cytology (as opposed to PAP) is 3 years for women less than 50 years old and 5 years for women over 50 years old. If a smear test is conducted and it shows no endocervical cells then it should be conducted again. This is because there was either inadequate preparation or sampling, or the sampling was done at the wrong point in the menstrual cycle. For severe dyskaryosis or carcinoma in situ, the patient needs treatment and should, therefore, be referred for a colposcopy. Clue cells are vaginal epithelial cells that are fuzzy (i.e.. without distinct edges) when looking at through a microscope. When bacterial vaginosis is present, over 20 per cent of the sample cells are clue cells. Bacterial vaginosis is treated with metronidazole therapy. Although trichomoniasis is treated with metronidazole too, the patient should be tested for other sexually transmitted diseases.

This patient has Klumpke’s paralysis due to damage to the T1 nerve root. This root eventually supplies the median and ulnar nerves. The ulnar nerve supplies all of the intrinsic hand muscles except for those of the thenar eminence and the first and second lumbricals, which are innervated by the median nerve.

The patient’s underlying arthritis has most likely led to Renal tubular acidosis RTA type 1, which presents with the following symptoms consistent with the presentation of the patient: Normal anion gap metabolic acidosis/acidaemia, hypokalaemia and hyperchloremia. Comparatively, the other conditions are ruled out because Aspirin and diabetic ketoacidosis is associated with a raised anion gap, Conn’s syndrome explains hypokalaemia but not the metabolic acidosis, and RTA type 4 is associated with hyperkalaemia.

Difficulty in breathing and unequal chest movements are due to paralysis of the diaphragm. So the nerve affected is the left phrenic nerve.

Over consumption of fluids, prolonged race duration and inadequate training all can predispose to acute hyponatraemia.
Mild symptoms include a decreased ability to think, headaches, nausea, and an increased risk of falls. Severe symptoms include confusion, seizures, and coma. Normal serum sodium levels are 135 – 145 mEq/liter (135 – 145 mmol/L). Hyponatremia is generally defined as a serum sodium level of less than 135 mEq/L and is considered severe when the level is below 120 mEq/L.
The correct treatment to give is hypertonic saline. Decompressive craniotomy would help alleviate raised intracranial pressure due to cerebral oedema however is not an appropriate first line treatment. Demeclocycline is used for SIADH and mannitol is more likely to be used in the context of traumatic brain injury.
Hyponatremia is corrected slowly, to lessen the risk of the development of central pontine myelinolysis (CPM), a severe neurological disease involving a breakdown of the myelin sheaths covering parts of nerve cells. During treatment of hyponatremia, the serum sodium (salt level in the blood) should not rise by more than 8 mmol/L over 24 hours.

Pulmonary metastasis is seen in 20-54% of extrathoracic malignancies. The lungs are the second most frequent site of metastases from extrathoracic malignancies. Twenty percent of metastatic disease is isolated to the lungs. The development of pulmonary metastases in patients with known malignancies indicates disseminated disease and places the patient in stage IV in TNM (tumour, node, metastasis) staging systems.
Chest radiography (CXR) is the initial imaging modality used in the detection of suspected pulmonary metastasis in patients with known malignancies. Chest CT scanning without contrast is more sensitive than CXR.
Breast, colorectal, lung, kidney, head and neck, and uterus cancers are the most common primary tumours with lung metastasis at autopsy. Choriocarcinoma, osteosarcoma, testicular tumours, malignant melanoma, Ewing sarcoma, and thyroid cancer frequently metastasize to lung, but the frequency of these tumours is low.

In any patient with asthma, a decreasing PaO2 and an increasing PaCO2, even into the normal range, indicates severe airway obstruction that is leading to respiratory muscle fatigue and patient exhaustion.

Chest tightness and cough, which are the most common symptoms of asthma, are probably the result of inflammation, mucus plugs, oedema, or smooth muscle constriction in the small peripheral airways. Because major obstruction of the peripheral airways can occur without recognizable increases of airway resistance or FEV1, the physiologic alterations in acute exacerbations are generally subtle in the early stages. Poorly ventilated alveoli subtending obstructed bronchioles continue to be perfused, and as a consequence, the P(A-a)O2 increases and the PaO2 decreases. At this stage, ventilation is generally increased, with excessive elimination of carbon dioxide and respiratory alkalemia.

This presentation is known as ‘Saturday night palsy’. When someone falls asleep with a arm hanging over the arm rest of a chair, the radial nerve compresses and causes wrist drop and loss of sensation at the web of the thumb.

Osteomalacia is a marked softening of the bones that can present in both type I and type II Renal Tubular Acidosis (RTA) and will thus not differentiate the two types in any case. The other measures will allow differentiation of the two types.

Up to 10% of postpartum women may develop lymphocytic thyroiditis (postpartum thyroiditis) in the 2-12 months after delivery. The frequency may be as high as 25% in women with type 1 diabetes mellitus.

Some patients return spontaneously to a euthyroid state within a few months, but most patients experience a phase of hypothyroidism that takes 2 to 6 months to resolve; of this group, some develop permanent hypothyroidism. About 50% of patients, however, will develop permanent hypothyroidism within 5 years of the diagnosis of postpartum thyroiditis.

High titres of anti-TPO antibodies during pregnancy have been reported to have high sensitivity and specificity for postpartum autoimmune thyroid disease.

In such a clinical scenario, NICE guidelines support initiating treatment with bisphosphonates without waiting for a DEXA scan.

Osteoporosis is defined as low bone mineral density caused by altered bone microstructure ultimately predisposing patients to low-impact, fragility fractures.

Management:
Vitamin D and calcium supplementation should be offered to all women unless the clinician is confident they have adequate calcium intake and are vitamin D replete
Alendronate is the first-line treatment. Around 25% of patients cannot tolerate alendronate, usually due to upper gastrointestinal problems. These patients should be offered risedronate or etidronate.
Strontium ranelate and raloxifene are recommended if patients cannot tolerate bisphosphonates.
Other medications that are useful in the treatment of osteoporosis are denosumab, teriparatide, raloxifene, etc.

Serum gastrin level will helps in the diagnosis of Zollinger-Ellison syndrome, which is characterised by a  history of recurrent and multiple gastric ulcers, due to increase gastrin secretion by the cells.

Many of the symptoms favour blast cells: the patient’s young age; a reoccurring sore throat caused by neutropenia and abnormal lymphoblasts; pale conjunctiva due to reduced production of red blood cells (this is because the marrow has been occupied by blast cells). There are no risk factors present for aplastic anaemia, and congenital aplastic anaemia would present itself earlier in life. A bone marrow aspiration would be needed to confirm the diagnosis.

This case is most likely tumour lysis syndrome, often occurring immediately after starting chemotherapy because the tumour cells are killed and their contents are released into the bloodstream. After treating lymphomas or leukaemia, there is a sudden hypocalcaemia, hyperphosphatemia, and hyperkalaemia

This patient has Wilson’s disease. They Kayser-Fleischer ring (ring that encircles the iris) is diagnostic of this. Low serum copper is seen in Wilson’s disease. With the Kayser-Fleischer ring, this makes all of the other answer choices incorrect.

The best option would be the combination of ampicillin and gentamycin. Changing to IV amoxicillin+gentamycin is however the best among the given choices here.

Opioid analgesics produce pain relief by attaching to the opioid receptors in the brain. Out of these, codeine is the least potent and diamorphine the most potent. Codeine is used to relieve mild to moderate pain. Morphine is a stronger analgesic used to treat pain like that experienced after surgery or injury. Oxycodone acts like the endorphins in the brain and reduces pain sensation. It is more potent than codeine and morphine and is used for relieving moderate to severe forms of pain. Among the listed, diamorphine is the most potent opioid analgesic. It is administered intravenously, subcutaneously, or intramuscularly to treat severe pain after surgery or in terminally-ill patients.

Dopamine (DA) holds a predominant role in the regulation of prolactin (PRL) secretion. Through a direct effect on anterior pituitary lactotrophs, DA inhibits the basally high-secretory tone of the cell. It accomplishes this by binding to D2 receptors expressed on the cell membrane of the lactotroph, activation of which results in a reduction of PRL exocytosis and gene expression by a variety of intracellular signalling mechanisms.

Good prognosis of chronic lymphocytic leukaemia (CLL) is associated with deletion of the long arm of chromosome 13 (del 13q). This is the most common abnormality, seen in around 50% of all CLL patients. Poor prognosis of the disease is related to deletion of part of the short arm of chromosome 17 (del 17p). This is seen in around 5-10% of the patients suffering from CLL.

Poor prognostic factors of CLL include:
1. Male sex
2. Age >70 years
3. Lymphocyte count >50
4. Prolymphocytes comprising more than 10% of blood lymphocytes
5. Lymphocyte doubling time <12 months
6. Raised LDH
7. CD38 expression positive

Diabetes insipidus (DI) is defined as the passage of large volumes (>3 L/24 hr) of dilute urine (< 300 mOsm/kg). It has the following 2 major forms:
– Central (neurogenic, pituitary, or neurohypophyseal) DI, characterized by decreased secretion of antidiuretic hormone (ADH; also referred to as arginine vasopressin [AVP])
– Nephrogenic DI, characterized by decreased ability to concentrate urine because of resistance to ADH action in the kidney
This patient has the central type from metastases.
In patients with central DI, desmopressin is the drug of choice. It is a synthetic analogue of antidiuretic hormone (ADH). It is available in subcutaneous, IV, intranasal, and oral preparations. Generally, it can be administered 2-3 times per day. Patients may require hospitalization to establish fluid needs. Frequent electrolyte monitoring is recommended during the initial phase of treatment.

The branches of the common peroneal nerve innervate the skin of the dorsum of the foot as well as the muscles which help to carry out dorsiflexion of the foot. Compression of the common peroneal nerve cause foot drop as well as the loss in sensation of the skin on the dorsum of the foot.

5-15% of the cases of polycythaemia vera progress to myelofibrosis or acute myeloid leukaemia (AML).

Polycythaemia vera (PV), also known as polycythaemia rubra vera, is a myeloproliferative disorder caused by clonal proliferation of marrow stem cells leading to an increase in red cell volume, often accompanied by overproduction of neutrophils and platelets. It has peak incidence in the sixth decade of life, with typical features including hyperviscosity, pruritus, splenomegaly, haemorrhage (secondary to abnormal platelet function), and plethoric appearance.

Some management options of PV include lose-dose aspirin, venesection (first-line treatment), hydroxyurea (slightly increased risk of secondary leukaemia), and radioactive phosphorus (P-32) therapy.

In PV, thrombotic events are a significant cause of morbidity and mortality. 5-15% of the cases progress to myelofibrosis or AML. The risk of having AML is increased with chemotherapy treatment.

HIV-associated nephropathy (HIVAN) show typical findings of scarring called focal segmental glomerulosclerosis (FSGS) and microcystic tubular dilatation, prominent podocytes, and collapsing capillary loops.

11-beta hydroxylase is stimulated by ACTH and responsible for conversion of 11-deoxycortisol to cortisol and deoxycorticosterone to corticosterone.

In 11-beta hydroxylase deficiency, the previously mentioned conversions are partially blocked, leading to:
– Increased levels of ACTH
– Accumulation of 11-deoxycortisol (which has limited biological activity) and deoxycorticosterone (which has mineralocorticoid activity)
– Overproduction of adrenal androgens (DHEA, androstenedione, and testosterone)

In hereditary non-polyposis colonic carcinoma (HNPCC), mutations in MSH2, MSH6, PMS2 or MLH1 genes are found.
Ataxia telangiectasia – ATM gene is affected.
Familial adenomatous polyposis – APC gene is affected.
Li-Fraumeni syndrome – mutation of the TP53 tumour suppressor gene. Neurofibromatosis – mutation in or a deletion of the NF1 gene

Rasburicase is a recombinant version of urate oxidase which is an enzyme that metabolizes uric acid to allantoin.

TLS is a potentially fatal condition occurring as a complication during the treatment of high-grade lymphomas and leukaemias. It occurs from the simultaneous breakdown (lysis) of the tumour cells and subsequent release of chemicals into the bloodstream. This leads to hyperkalaemia and hyperphosphatemia in the presence of hyponatraemia. TLS can occur in the absence of chemotherapy, but it is usually triggered by the introduction of combination chemotherapy. Awareness of the condition is critical for its prophylactic management.

Patients at high risk of TLS should be given IV rasburicase or IV allopurinol immediately prior to and during the first few days of chemotherapy. Allantoin is much more water soluble than uric acid and is therefore more easily excreted by the kidneys. Patients in lower-risk groups should be given oral allopurinol during cycles of chemotherapy in an attempt to avoid the condition.

TLS is graded according to the Cairo-Bishop scoring system as:
1. Laboratory tumour lysis syndrome
2. Clinical tumour lysis syndrome

The patient could respond well to palliative radiotherapy. This course of action is likely to shrink the cancer and will, therefore, reduce the pain felt. Analgesics should then be used to control the symptoms.

Bendroflumethiazide is a drug used for treating hypertension and is a diuretic. It produces side effects such as constipation, frequent urination, fatigue, polydipsia etc.