The most probable diagnosis for this patient would be a duplex kidney with an ectopic ureter inserting below the bladder neck. Rationale: The Weigert-Myer law states that the upper moiety ureter inserts inferior and medial to the lower moiety ureter. Other options:- Horseshoe kidney would display as a single pelvic kidney on an ultrasound scan.- Ureterocele would be a cystic lesion within the bladder or may prolapse at birth. – Continence should not be affected by polycystic kidney disease. – The overactive bladder would cause frequency and urgency, neither of which is mentioned in the history.

Minimal change nephrotic syndrome leads to the loss of anti-thrombin III which protects the body from forming venous emboli. It may be triggered by virus, immunisations, medication, non-Hodgkin lymphoma, or leukaemiaCharacterised by oedema, proteinuria, hypoalbuminemia, and hypercholesterolemia.

ADH primarily acts on the collecting ducts.Other options:- The juxtaglomerular apparatus is the site of renin production.- The proximal tubule conducts isosmotic reabsorption of about 60% of sodium chloride and volume. Most of the glucose, amino acids, potassium and phosphate are absorbed here.- The loop of Henle is the site of 25% of sodium reabsorption. Active Chloride transport provides the basis for the counter current multiplier aiding urinary concentration.- The distal convoluted tubule is impermeable to water and acts via active sodium chloride absorption to dilute urine.

The cells in the testes that secrete testosterone are the Leydig cells.Other cells in testes include:- Spermatogonia: These are undifferentiated male germ cells which undergo spermatogenesis in the seminiferous tubules of the testes.- Sertoli cells: They are a part of the seminiferous tubule of the testes, cells are activated by FSH and nourish developing sperm cells.- Myoid: They are squamous contractile cells which generate peristaltic waves, they surround the basement membrane of testes.- Fibroblasts: Cells which synthesise collagen and the extracellular matrix.

The child requires frequent BP evaluation every 15 to 30 minutes. Normalisation of his BP should be achieved in a 48h interval. An ophthalmology assessment is indicated to check for acute injury of the blood vessels in the eye due to the elevated blood pressure.

Vesicoureteral reflux is a common disorder in children but can result in kidney scarring following acute pyelonephritis. The gold standard diagnostic test to detect renal scars in children is 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy

Immunoglobulin G (IgG) glomerular immune deposits are seen more commonly in HSP compared to IgA nephropathy.The presentation of the child is highly suggestive of Henoch-Schönlein purpura (HSP). It is an IgA-mediated, autoimmune hypersensitivity vasculitis that targets the small vessels of the skin, GI tract, kidneys, and joints.It is most commonly seen in children aged 3 – 6years and is twice as common in boys than girls. Preceding viral URTI with low-grade pyrexia is common. The most common organism associated with HSP is, however, Group A streptococcal infection A.A purpuric rash is seen on the back of the legs and buttocks and can less frequently, affect the arms. Arthralgia is common (usually knees/ankles) in these patients. Abdominal pain and bloody diarrhoea may occur. And half of the children with HSP have renal involvement. Rarely, it can lead to end-stage renal failure.Treatment includes adequate hydration, occasionally steroids, and other immunosuppressants. The disease can recur in 1 in 3 children.

Among the options provided, the most characteristic finding that can be expected in his patient’s urine microscopy is RBC casts. Red cell casts are a characteristic feature of acute nephrotic syndrome. Other options:- Hyaline casts may be seen in normal urine, particularly after exercise. – Coarse granular casts occur in glomerular and tubular disease. – Tubular cell casts may be seen in patients with acute tubular necrosis. – The presence of 10 or more white blood cells/mm3 is abnormal and indicates an inflammatory reaction, most commonly due to infection.

Allergy: A history of a prior allergic-like reaction to contrast media is associated with an up to a 5-fold increase in the likelihood of experiencing a subsequent reaction. Also, any patient with a predilection to allergic reactions may predispose them to a reaction after the administration of contrast media. Given the increased risk of severe life-threatening anaphylaxis related to the administration of contrast media in the setting of the history of atopy, the risk versus benefits should be discussed before following through with the procedure. A premedication regimen may be used to reduce the risk of anaphylaxis.Asthma: A history of asthma may be indicative of a higher likelihood of developing a contrast reaction. Cardiac status: Attention must be turned to patients with significant cardiac disease (congestive heart failure, aortic stenosis, severe cardiomyopathy, and/or pulmonary hypertension), as higher volumes and osmolality of contrast material may result in an increased risk for a contrast reaction.Renal insufficiency: Contrast nephrotoxicity is defined as the rapid deterioration of renal function after the administration of contrast media when no other aetiology can be determined from the clinical records. The major predisposing risk factors include pre-existing renal insufficiency (defined as serum creatinine level >1.5 mg/dL) and diabetes. Other risk factors include dehydration, cardiovascular disease, the use of diuretics, advanced age (>70 years old), hypertension, and hyperuricemia. Obtaining multiple contrast-enhanced studies within 24 hours is also thought to increase the risk for contrast-induced nephrotoxicity. Miscellaneous: Relative contraindications to the use of high osmolality iodinated contrast media (HOCM) in patients with pheochromocytoma, sickle cell disease, and multiple myeloma have been reported. Although the administration of low osmolality or iso-osmotic contrast media may be beneficial in patients with pheochromocytoma and sickle cell disease, little evidence suggests that these agents mitigate the risks associated with multiple myeloma.

Polyuria is defined as a total increase in the urine output or > 2L/m2 of daily urine produced in children. Polyuria can be a symptom of a vast number of medical conditions. The commonest and most important disease having polyuria as the main symptom is diabetes mellitus. Nephrogenic and central diabetes insipidus also results in polyuria along with polydipsia. Other conditions that lead to an increase in the urine output are renal failure, acute tubular necrosis, and exposure to high altitude. Hyperkalaemia does not result in polyuria| rather hypokalaemia can be an associated finding with polyuria in the case of diuretic abuse.

Hyperkalaemia is not to evaluate or detect AKI but rather the result of it. If one of the rest of the options is present, then AKI would be suspected.

Vesicoureteric reflex (VUR) is described as the retrograde flow of urine from the bladder into the ureter due to an incompetent uterovesical junction. In primary VUR the lower urinary tract functions normally, while secondary VUR is associated with a poorly functioning lower urinary tract. The incidence of VUR is highest in new-born girls. They can present with hydronephrosis, or urinary tract infections.

Gitelman syndrome is a kidney disorder that causes an imbalance of charged atoms (ions) in the body, including ions of potassium, magnesium, and calcium.The signs and symptoms of Gitelman syndrome usually appear in late childhood or adolescence. Common features of this condition include painful muscle spasms (tetany), muscle weakness or cramping, dizziness, and salt craving. Also common is a tingling or prickly sensation in the skin (paraesthesia), most often affecting the face. Some individuals with Gitelman syndrome experience excessive tiredness (fatigue), low blood pressure, and a painful joint condition called chondrocalcinosis. Studies suggest that Gitelman syndrome may also increase the risk of a potentially dangerous abnormal heart rhythm called ventricular arrhythmia.

Distal renal tubular acidosis (dRTA) is characterised by a decreased hydrogen ion excretion from the alpha intercalated cells of the collecting duct of the distal nephron. The resultant acidosis causes calcium and phosphates to be released from bones to buffer the acidosis causing hypercalciuria. This precipitates calcium compounds in the kidney, predisposing it to renal stone formation. On the other hand, proximal renal tubular acidosis is characterised by an impairment in bicarbonate resorption. Both types lead to metabolic acidosis and electrolyte imbalances including potassium depletion. Children often present with failure to thrive. One way to differentiate between the two conditions is with an acid challenge test. In proximal RTA (type 2) administering an ammonium chloride load will decrease the urinary pH whereas in distal disease (type 1), the urine pH will not decrease below 5.3.

Minimal change glomerulonephritis presents with mild or benign urinalysis findings. However, proteinuria together with the presence of oval fat bodies are typical.Minimal change glomerulonephritis (nephropathy) accounts for most cases of childhood nephrotic syndrome and 20–25% of adult nephrotic syndrome.

The most probable diagnosis for this patient would be torsion of a hydatid cyst of the testis.Note:The differential diagnoses in acute testicular pain/swelling are listed in the possible answers. Testicular torsion typically affects adolescent males and presents with acute painful swelling and a horizontally lying testicle. Other options:- Epididymo-orchitis is diagnosed during surgery when a thickened erythematous epididymis is noted. Ectopic ureteric insertion into the vas must be excluded by ultrasound scan on an out-patient basis. The hydatid cyst or cyst of Morgagni represents the remnants of the Mullerian structure. In the pre-pubertal child, a surge in hormones can stimulate growth and chance of torsion. It is diagnosed by surgical exploration or by a blue dot sign. Idiopathic scrotal oedema tends to be within the scrotum itself, and the testis can be examined in the groin to exclude pain in the testis. All acute scrotal pain must be explored to exclude testicular torsion unless a surgical registrar is convinced of a torted hydatid cyst.- An 8-year-old is more likely to present with a torted hydatid cyst. The blue dot sign is diagnostic and can negate the need for surgical exploration. The age of the child also makes epididymo-orchitis less likely.- Idiopathic scrotal oedema presents with an erythematous and thickened scrotum. This can cross the midline and involve the whole scrotum.- Finally, an inguinal hernia would present with a mass in the groin extending to the scrotum that you cannot get above.

The patient shows features of neurofibromatosis. The most likely cause for hypertension in this patient would be renal artery stenosis.Note:Neurofibromatosis is an inherited autosomal dominant disorder which could have affected this girl’s father, and she appears to have the classic skin lesions. A renal bruit might be heard in these patients. Polycystic kidney disease can occur in association with tuberous sclerosis, which also has skin lesions associated (different from those described in this patient). Most causes of hypertension in childhood have underlying renal causes, and a renal ultrasound with doppler is the first-line investigation of choice. Even if this is normal, further imaging would be indicated here, for example, isotope renal scans and angiography.

Fanconi tubular syndrome is characterised by malabsorption of various electrolytes and substances commonly absorbed by the proximal tubule. Hypokalaemia, hypophosphatemia, and hyperchloremic metabolic acidosis is usually present. Also, urinalysis reveals an increased fractional excretion of glucose.

Using a Doppler device, you can estimate systolic BP even when the pulse is inaudible. Handheld and portable, the device uses ultrasound waves to detect the velocity of arterial blood flow. Helpful for patients with traumatic injuries or shock, the Doppler technique is also useful for children and patients whose BP is hard to hear because of oedema, obesity, vasoconstriction, or low cardiac output.

Diffuse proliferative glomerulonephritis is a term used to describe a distinct histologic form of glomerulonephritis common to various types of systemic inflammatory diseases, including autoimmune disorders (e.g., systemic lupus erythematosus [SLE]), vasculitis syndromes (e.g., granulomatosis with polyangiitis), and infectious processes. In DPGN, more than 50% of the glomeruli (diffuse) show an increase in mesangial, epithelial, endothelial (proliferative), and inflammatory cells (i.e., glomerulonephritis).

Progressive vomiting due to pyloric stenosis leads to hypochloraemic, hypokalaemic, metabolic alkalosis.

The most common manifestation of Wilms tumour is an asymptomatic abdominal mass| an abdominal mass occurs in 80% of children at presentation. Abdominal pain or haematuria occurs in 25%. Urinary tract infection and varicocele are less common findings than these. Hypertension, gross haematuria, and fever are observed in 5-30% of patients. A few patients with haemorrhage into their tumour may present with hypotension, anaemia, and fever. Rarely, patients with advanced disease may present with respiratory symptoms related to lung metastases.

The most probable cause for the child’s presenting symptoms and the findings in ultrasound would be the presence of an abnormal posterior urethral valve. A posterior urethral valve is a developmental anomaly that usually affects male infants (incidence 1 in 8000) leading to obstructive uropathy. Diagnostic features include bladder wall hypertrophy, hydronephrosis and bladder diverticula.Note:Posterior urethral valves are the most common cause of infra-vesical outflow obstruction in males. They can be diagnosed on antenatal ultrasonography. Due to the necessity of the fetal bladder to develop high emptying pressures in utero secondary to this anomaly, the child may develop renal parenchymal damage. This leads to renal impairment noted in 70% of boys at the time of presentation. Management:The immediate treatment would be to place a bladder catheter to relieve the acutely retained urine. The definitive treatment of choice would be an endoscopic valvotomy with a cystoscopic and renal follow up.

Based on the presented clinical scenario, the most probable diagnosis for the patient would be testicular torsion.Rationale:The gubernaculum is the structure responsible for aiding the descent of the testicles from the abdomen into the scrotum. The processus vaginalis precedes the descent of the testes and then undergoes closure. Abnormalities such as the persistence of a patent processus vaginalis, known as bell clapper deformity, predispose to testicular torsion.Other options:- Varicocele: Nutcracker syndrome occurs where the left renal vein becomes compressed in between the superior mesenteric artery and the aorta. Since the left gonadal vein drains into the left renal vein, this results in a varicocele. – Epididymitis and mumps orchitis are differentials for acute testicular pain but are not due to a defect in the processus vaginalis. – An incarcerated inguinal hernia presents mainly with signs of bowel obstruction which are not mentioned in the clinical scenario.The descent of testes:- Until the end of foetal life, the testicles are located within the abdominal cavity. – They are initially located on the posterior abdominal wall on a level with the upper lumbar vertebrae (L2). – Attached to the inferior aspect of the testis is the gubernaculum testis which extends caudally to the inguinal region, through the canal and down to the superficial skin. – It is interesting to note that both the testis and the gubernaculum are extra-peritoneal.- As the foetus grows, the gubernaculum becomes progressively shorter. It carries the peritoneum of the anterior abdominal wall (the processus vaginalis). As the processus vaginalis descends the testis is guided by the gubernaculum down the posterior abdominal wall and the back of the processus vaginalis into the scrotum.- By the third month of foetal life the testes are located in the iliac fossae, by the seventh they lie at the level of the deep inguinal ring.Usually, the processus vaginalis closes after birth but may persist predisposing to indirect hernias. On the other hand, a partial closure may result in the development of cysts on the cord.

The mesonephric duct is one of the paired embryogenic tubules that drain the primitive kidney (mesonephros) to the cloaca. It also gives off a lateral branch forming the ureteric bud. In both the male and the female the Wolffian duct develops into the trigone of the urinary bladder. When the ducts are exposed to testosterone during embryogenesis, male sexual differentiation occurs: the mesonephric duct develops into the rete testis, the ejaculatory ducts, the epididymis, the ductus deferens and the seminal vesicles.

The child has a history of pharyngitis followed 10 days later by signs of glomerulonephritis. In this particular case, it is most probably a post-streptococcus glomerulonephritis which accounts for 80% of paediatric cases of glomerulonephritis.

Nephrogenic Diabetes Insipidus is an acquired or hereditary condition that affects the water balance. It presents with polyuria and polydipsia, leading commonly to dehydration.

The most common physiological factors that influence renin secretion include renal perfusion pressure, renal sympathetic nerve activity, and tubular sodium chloride load.The perfusion pressure in the renal artery is the most profound parameter to influence renin secretion| when the renal perfusion pressure falls (i.e. hypovolaemia), renin secretion rises, and vice versa.

The child has nephrotic syndrome which is most commonly caused by minimal change nephropathy in this age group. The condition presents with fusion of foot processes of the glomerular epithelial cells under the microscope.

Fanconi syndrome is a rare disorder characterized by defective proximal renal tubular reabsorption, which leads to excessive excretion of potassium, phosphate, uric acid, bicarbonates, glucose, and certain amino acids in the urine. Loss of potassium in the urine leads to hypokalaemia, while the loss of phosphate may lead to hypophosphatemic rickets. The overall impact is the failure to thrive and growth retardation.