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.

The boy seems to have a varicocele so the most appropriate next step would be reassurance. A varicocele is an enlargement of the veins within the scrotum called the pampiniform plexus. A varicocele only occurs in the scrotum and is very similar to varicose veins that can occur in the leg. Because a varicocele usually causes no symptoms, it often requires no treatment.

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.

The most commonly requested biochemistry tests for renal function are the urea and electrolytes. They supply important information when it comes to homeostasis and excretion. Glomerular filtration rate is also the essential standard marker of kidney health and is assessed by checking the creatinine levels. In this case as the child has lost fluids and electrolytes, this test will indicate the extent of the loss and allow for more appropriate replacement.

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.

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.

The right testicular vein is a tributary of the inferior vena cava, while the left testicular vein drains into the left renal vein.
Note:
The testicular venous drainage begins in the septa and these veins together with those of the tunica vasculosa converge on the posterior border of the testis as the pampiniform plexus. The pampiniform plexus, in turn, drains to the testicular vein.

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.

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.

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.

Idiopathic hypercalciuria (IH) is the commonest metabolic abnormality in patients with calcium kidney stones. It is characterized by normocalcemia, absence of diseases that cause increased urine calcium, and calcium excretion that is above 250 mg/day in women and 300 mg/day in men. Subjects with IH have a generalized increase in calcium turnover, which includes increased gut calcium absorption, decreased renal calcium reabsorption, and a tendency to lose calcium from bone. Despite the increase in intestinal calcium absorption, negative calcium balance is commonly seen in balance studies, especially on a low calcium diet. The mediator of decreased renal calcium reabsorption is not clear; it is not associated with either an increase in filtered load of calcium or altered PTH levels. There is an increased incidence of hypercalciuria in first-degree relatives of those with IH, but IH appears to be a complex polygenic trait with a large contribution from diet to expression of increased calcium excretion. Increased tissue vitamin D response may be responsible for the manifestations of IH in at least some patients.

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

This is a case of nephrotic syndrome that can be confirmed by the presence of urinary albumin. It should be further investigated by a tissue sample to confirm the diagnosis.

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 child most likely has nephritic syndrome which is characterised by a reduced renal function, proteinuria of non-nephrotic range, haematuria, erythrocyte casts, and oedema.

Polyarteritis nodosa usually occurs in middle-aged men but can also be seen in young children. It is accompanied by severe systemic manifestations such as fever, malaise, weight loss and myalgia.

Renal cell carcinoma usually presents around 55 years with the classic triad of haematuria, loin pain and a unilateral mass in the flank.

Polycystic kidney disease usually presents in adult life with acute loin pain and palpation of masses in the flanks.

Prepubertal atrophic vaginitis is due to a lack of vaginal oestrogen. The pathophysiology behind prepubertal atrophic vaginitis:
1.The proximity of the vagina to the anus
2.Lack of oestrogen – leads to thinning of the vaginal mucosa
3.Lack of pubic hair to protect the area
4.Lack of labial fat pads

A micturating cystourethrogram (MCUG) is one type of imaging test also called a voiding cystourethrogram (VCUG). The MCUG can check whether the flow of urine from the child’s bladder is being blocked, or whether it goes up the wrong way. It can help diagnose certain conditions, including vesicoureteral reflux and posterior urethral valves.

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.

Oligomenorrhoea and BMI of 40.4 is suggestive of Polycystic ovary syndrome (PCOS). To diagnose PCOS 2 out of following 3 criteria should be present : oligo/anovulation, hyperandrogenism, clinical (hirsutism or less commonly male pattern alopecia) or biochemical (raised FAI or free testosterone) and polycystic ovaries on ultrasound.

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.

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.

A teratoma is a tumour containing tissue elements that are similar to normal derivatives of more than one germ layer. They usually contain skin, hair, teeth and bone tissue and are more common in children, behaving as a benign tumour. After puberty, they are regarded as malignant and can metastasise.

The boy is most probably a type 1 diabetic patient. Such a condition can affect the behaviour and psychological state of a young child reflected in their behaviour. The parents should seek the help of a clinical psychologist.

Minimal-change disease (MCD) refers to a histopathologic glomerular lesion, typically found in children, that is almost always associated with nephrotic syndrome. The most noticeable symptom of MCD is oedema, which can develop very rapidly. Due to the renal loss of proteins muscle wasting and growth failure may be seen in children. Renal function is usually not affected and a proteinuria of more than 40 mg/h/m2 is the only abnormal finding in urinalysis.

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.

Answer: Torsion of a testicular hydatid

The appendix testis (or hydatid of Morgagni) is a vestigial remnant of the Mullerian duct, present on the upper pole of the testis and attached to the tunica vaginalis. It is present about 90% of the time. The appendix of testis can, occasionally, undergo torsion (i.e. become twisted), causing acute one-sided testicular pain and may require surgical excision to achieve relief. One third of patients present with a palpable blue dot discoloration on the scrotum. This is nearly diagnostic of this condition. If clinical suspicion is high for the serious differential diagnosis of testicular torsion, a surgical exploration of the scrotum is warranted. Torsion of the appendix of testis occurs at ages 0-15 years, with a mean at 10 years, which is similar to that of testicular torsion.

Occasionally a torsion of the hydatid of Morgagni can produce symptoms mimicking those created by a testicular torsion; a torsion of the hydatid, however, does not lead to any impairment of testicular function.
Absence of the cremasteric reflex is a sign of testicular torsion. This therefore confirms that the diagnosis is Torsion of a testicular hydatid.

A 10 year old child, with a history of URTI and haematuria, presents a picture consistent with a diagnosis of IgA nephropathy. This condition can present with proteinuria and generalized swelling. However, an important differentiating point from rapidly progressive GN is the duration. IgA nephropathy is usually <10 days (commonly 4-5 day history of infection).

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).

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 likely diagnosis in this case is Haemolytic Uremic Syndrome (HUS), which is generally seen in young children presenting with a triad of symptoms, namely: acute renal failure, microangiopathic haemolytic anaemia, and thrombocytopenia. The typical cause of HUS is ingestion of a strain of Escherichia coli. The laboratory results will usually include fragmented RBCs, decreased serum haptoglobin, reduced platelet count, nonspecific WBC changes, and normal coagulation tests (PTT included).

Urine culture and sensitivity is used to diagnose a urinary tract infection (UTI). A mid-stream clean catch urine sample is the most common type of sample collected. It is important to follow the clean catch process to have accurate results from an uncontaminated sample. Urine cultures can also check for infections of the bladder or kidney.

As this boy has experienced significant dry spells in the past, it is unlikely that a structural abnormality is causing the enuresis. The only therapies that have been shown to be effective in randomized trials are alarm therapy and treatment with desmopressin acetate or imipramine. Bladder training exercises are not recommended. Desmopressin acetate is the preferred medication for treating children with enuresis.

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.

Rhabdomyosarcoma originates from skeletal muscle cells. A biopsy is needed for grading according to microscopy. Most patients are adult females.

Diarrhoea is defined as having three or more loose or liquid stools per day, or as having more stools than is normal for that person. Severe diarrhoea, causing fluid loss and loss of bicarbonate, will result in marked dehydration and metabolic acidosis.

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

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.

Minimal change disease is a type of glomerulonephritis that mostly affects younger children. Proteinuria is present which leads to body oedema. But in these patients blood pressure is normal.

Among the given options, the most likely cause for the patient’s presenting symptoms is acute interstitial nephritis secondary to anti-tubercular therapy (ATT)
Drug-induced acute interstitial nephritis can occur following treatment with beta-lactams, sulphonamides, rifampicin, ethambutol, and erythromycin. They can cause an acute allergic reaction with the infiltration of immune cells.
Acute interstitial nephritis is said to be the most common renal complication in patients undergoing anti-TB treatment. Rifampicin is the most implicated drug, although ethambutol can also be a cause. The pathogenesis involves an immune-complex mediated acute allergic response, which leads to their deposition on renal vessels, the glomerular endothelium, and the interstitial area.

Other options:
Isoniazid does not affect the kidneys.
Pulmonary-renal syndrome is a feature of Goodpasture’s syndrome. It is characterized by renal failure and lung haemorrhage. Severe cardiac or renal failure ensues and is complicated by pulmonary oedema, systemic lupus erythematosus, Henoch-Schonlein purpura, and cryoglobulinemia.

Prophylactic antibiotics should be given to the child to avoid infections and renal injury.

Alport syndrome is a genetic condition characterized by kidney disease, hearing loss, and eye abnormalities.
Alport syndrome can have different inheritance patterns. About 80 percent of cases are caused by mutations in type IV collagen genes (COL4A5) and are inherited in an X-linked autosomal recessive pattern.
Alport syndrome has autosomal dominant inheritance in about 5 percent of cases.
People with Alport syndrome experience progressive loss of kidney function. Almost all affected individuals have blood in their urine (haematuria), which indicates abnormal functioning of the kidneys. Many people with Alport syndrome also develop high levels of protein in their urine (proteinuria). The kidneys become less able to function as this condition progresses, resulting in end-stage renal disease (ESRD).
People with Alport syndrome frequently develop sensorineural hearing loss, which is caused by abnormalities of the inner ear, during late childhood or early adolescence. Affected individuals may also have misshapen lenses in the eyes (anterior lenticonus) and abnormal coloration of the light-sensitive tissue at the back of the eye (retina). These eye abnormalities seldom lead to vision loss.
Significant hearing loss, eye abnormalities, and progressive kidney disease are more common in males with Alport syndrome than in affected females.

According to WHO, the treatment protocol in severely dehydrated children, is to infuse a bolus of isotonic crystalloid over 20-30 min at 30ml/kg to children less than 12 months of age followed by giving the remaining fluid over 5 hours for infants. Reference: World Health Organisation, the treatment of diarrhoea, a manual for physical and senior health workers.

The percentages of body water contained in various fluid compartments add up to total body water (TBW). This water makes up a significant fraction of the human body, both by weight and by volume. Ensuring the right amount of body water is part of fluid balance, an aspect of homeostasis. The extracellular fluid (ECF) includes all fluids outside the cells. This fluid can be divided into three fluid departments: interstitial (in the tissue spaces) fluid, blood plasma and lymph, and specialised compartments called transcellular fluid. The extracellular fluid surrounds all the cells in the body and is in equilibrium with the intracellular fluid. So, its composition must remain fairly constant even though substances are passing into and out of the cells. The interstitial fluid, though called a fluid, is in a reality a gel-like composition made up of: water, proteoglycan molecules and collagen. The extracellular fluid constitutes 40% of total body water, with intracellular fluid making up the remaining 60%. It is relatively rich in glucose.

Renal scaring resulting from urinary tract infections can best be determined using Dimercaptosuccinic acid (DMSA) scintigraphy. The scan utilises technetium-99 mixed with the DMSA which is injected into the bloodstream. The radiological dye is taken up by the kidney where it binds to the proximal convoluted tubules. It therefore detects the size, shape and position of the kidney and any scars but is not as useful in assessing dynamic renal excretion. Ultrasound scans are better suited to assess hydronephrosis and dilated ureters. MAG3 scans and MCUG are able to determine the function of kidneys and detect obstructions such as posterior urethral valves and reflux.

Haemolytic uremic syndrome belongs to a heterogeneous group of disorders characterized by a triad of thrombocytopenia, microangiopathic haemolytic anaemia, and acute kidney injury. It is one of the most common causes of renal injury in children. The clinical findings are due to thrombotic microangiopathy, which leads to arterioles and capillary wall thickening along with endothelial swelling and detachment. The significant laboratory findings include increased white cell count, raised serum urea and creatinine, increased serum LDH, decreased platelet count, haematuria, and proteinuria.

Hypospadias is an abnormality of anterior urethral and penile development. The urethral opening is located on the ventral aspect of the penis proximal to the tip of the glans penis, which, in this condition, is open. The urethral opening may be located as proximal as in the scrotum or perineum. The penis may also have associated ventral shortening and curvature, called chordee, with more proximal urethral defects.

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.

Membranoproliferative glomerulonephritis primarily affects children and young adults, with patients presenting with nephrotic or nephritic syndrome or with asymptomatic renal disease. There are 3 types defined by pathologic features. All three types are associated with hypocomplementemia, but they manifest somewhat different mechanisms of complement activation. This type of glomerulonephritis often progresses slowly to end-stage renal disease, and it tends to recur after renal transplantation, especially type II.

The presentation is suggestive of nephrotic syndrome. A trial of corticosteroids is the first step in treatment of idiopathic nephrotic syndrome. Diuretics are useful in managing symptomatic oedema. Cyclosporin and cyclophosphamide are indicated in frequently relapsing and steroid dependant disease.

IgA nephropathy’s characteristic presentation is haematuria following a non-specific upper respiratory infection as was evident in this case. IgA nephropathy also usually occurs in children and young males, like this patient.

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.

Renal stones < 5mm generally pass spontaneously with adequate fluid intake. Stones 5mm-10mm with pain not resolving, require medical expulsive therapy with Nifedipine or Tamsulosin. For stones larger than 10mm, ESWL or Ureteroscopy is indicated. For stones as big as 2cm, percutaneous nephrolithotomy should be applied.

In nephrotic syndrome, one of the main pathological processes is the excretion of protein by the kidneys. The resultant signs including; low serum albumin, oedema and hypovolemia all occur as a result of fluid escaping into the extracellular space due to a low oncotic pressure. While an albumin infusion may help to increase oncotic pressure, its indications specifically include hypovolemia, which is assessed by a capillary refill time more than 5 seconds, an elevated haematocrit, or severe symptomatic oedema, such as scrotal oedema. Hypertension not an indication for an infusion, and most patients needing an albumin infusion have oliguria.

Tuberous sclerosis presents with the growth of numerous noncancerous (benign) tumours in many parts of the body. They may appear in the brain, kidneys, skin or various other organs.

The presenting features with the positive pregnancy test are highly suggestive of gestational diabetes mellitus.

Diabetes Insipidus:
It is much less common than gestational diabetes mellitus. It is characterised by the inability to concentrate urine, with marked thirst.

Presenting symptoms include polydipsia (>3L daily), polyuria, nocturia, nocturnal enuresis.
Physical examination may reveal features of dehydration and an enlarged bladder.
Investigations include biochemical analysis for electrolytes, urine and plasma osmolality, fluid deprivation test, and cranial MRI.

The main differential diagnosis is for diabetes insipidus is psychogenic polydipsia.

There are three broad categories of diabetes insipidus (DI):
– Central (cranial) DI:
It is the most common form of diabetes insipidus.
It occurs due to decreased secretion of ADH. It usually occurs due to hypothalamic disease and may show response to low-dose desmopressin.
– Peripheral (nephrogenic) DI:
It is characterised by the resistance of the kidney to ADH.
It usually does not respond to low-dose desmopressin.
– Gestational DI:
It is rare and is mostly seen in teenage pregnancy.
It usually presents in the third trimester and often resolves 4-6 weeks post-partum.

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-Schonlein 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.

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.

Urine culture confirms a diagnosis of a UTI. A kidney ultrasound will be the next best investigation because it will help us to visualise the bladder, kidneys, and ureters to rule out any congenital obstruction in the urinary tract that might be the actual cause of infection in this 2-month old girl.

Liddle’s syndrome,  is an autosomal dominant disorder, that is characterized by early, and frequently severe, high blood pressure associated with low plasma renin activity, metabolic alkalosis, low blood potassium, and normal to low levels of aldosterone. Liddle syndrome involves abnormal kidney function, with excess reabsorption of sodium and loss of potassium from the renal tubule. Bartter Syndrome also presents with hypokalaemia, however blood pressure of these patients is usually low or normal.

The most probable diagnosis for this patient is bilateral retractile testes. This a normal phenomenon in some pre-pubertal boys.

Rationale:
Testicular descent can continue until about 3-months of age. The pre-pubertal testis is small enough that with activation of the cremasteric reflex, they can enter the inguinal canal.
This in itself is a normal finding providing the testis can be brought into the scrotum without tension and does not require surgical correction. With time the testis will lie within the scrotum.

Orchidopexy for true undescended testis can be performed from 6-months of age. It is also warranted if the testes remain undescended or intra-abdominally leading to infertility.

Other options:
– An ascending testis is one, typically, following hernia or orchidopexy surgery that was in the testis but with time is within the inguinal canal and cannot be brought into the scrotum. Orchidopexy is required for this.
– No surgery is required as when the testis enlarges with puberty it will remain within the scrotum.
– The testes can be brought into the scrotum. Therefore they are not undescended.
– The testes are retractile not ascending; ascending testis cannot be brought into the scrotum and would require orchidopexy.

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.

The likely diagnosis in this case is Haemolytic Uremic Syndrome (HUS), which is generally seen in young children presenting with a triad of symptoms, namely: acute renal failure, microangiopathic haemolytic anaemia, and thrombocytopenia. The typical cause of HUS is ingestion of a strain of Escherichia coli causing diarrhoea in these cases as well.

Haematuria and abdominal swelling may indicate either polycystic kidney disease or a tumour. Because of the patient’s age, the likelihood of a tumorous growth is small, thus an ultrasound is the best choice for this case.

Von Hippel-Lindau syndrome is a genetic disorder inherited in autosomal dominant fashion. It is caused by the mutations of the VHL gene located on chromosome 3. The syndrome is characterized by the creation of multiple benign and malignant tumours involving various bodily systems along with the formation of numerous visceral cysts, including the renal and epididymal cysts.
Down’s syndrome is associated with renal cysts, but it does not follow the autosomal dominant mode of inheritance, rather it is caused by non-disjunction of chromosome 21 during meiosis.
Exomphalos is a defect of the medial abdominal wall leading to abnormal protrusion of abdominal viscera through it. It is not associated with renal cysts.
Turner’s syndrome may be associated with renal cysts formation, but it is not transmitted in an autosomal dominant fashion.
Polycystic kidney disease of childhood follows an autosomal recessive pattern of transmission.

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.

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.

Because the medical history included tonsillitis followed by haematuria and hypertension, there is a strong suspicion of a case of post-streptococcal glomerulonephritis (PSGN). Patients with PSGN usually have serological findings showing depressed serum haemolytic component CH50 and serum concentrations of C3. Sometimes depressed C4 levels are also apparent, but not always, therefore, the answer to this question is: depressed CH50 level.

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.

USG of the scrotum is important to exclude any abnormality with testicles, epididymis and scrotum. This presentation can be acute epididymo-orchitis or testicular torsion. USG of the scrotum will help to confirm the diagnosis.

Angio-oedema, is the rapid swelling of the skin, mucosa and submucosal tissues. The underlying mechanism typically involves histamine or bradykinin. The version related to histamine is to due an allergic reaction to agents such as insect bites, food, or medications. The version related to bradykinin may occur due to an inherited C1 esterase inhibitor deficiency, medications e.g. angiotensin converting enzyme inhibitors, or a lymphoproliferative disorder.

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 leukaemia
Characterised by oedema, proteinuria, hypoalbuminemia, and hypercholesterolemia.

Metabolic alkalosis is characterized by a primary increase in the concentration of serum bicarbonate ions. This may occur as a consequence of a loss of hydrogen ions or a gain in bicarbonate. Hydrogen ions may be lost through the kidneys or the GI tract, as for example during vomiting, nasogastric suction or use of diuretics. Intracellular shifting of hydrogen ions develops mainly during hypokalaemia to maintain neutrality. Gain in bicarbonate ions may develop during administration of sodium bicarbonate in high amounts or in amounts that exceed the capacity of excretion of the kidneys, as seen in renal failure. Fluid losses may be another cause of metabolic alkalosis, causing the reduction of extracellular fluid volume.

Unless given IV, a drug must cross several semipermeable cell membranes before it reaches the systemic circulation. Drugs may cross cell membranes by diffusion, amongst other mechanisms. The rate of diffusion of a substance is proportional to the difference in the concentration of the diffusing substance between the two sides of the membrane, the temperature of the solution, the permeability of the membrane and, in the case of ions, the electrical potential difference between the two sides of the membrane.

E. coli accounts for the majority of UTI’s in children. If this child responds well to treatment and has no recurrence of his symptoms, then no form of imaging is required, as per NICE advice for children aged 6 months to 3 years. Had the child been less than 6 months of age, then a USS at 6 weeks would be necessary.

Other options:
– Pseudomonas causes atypical UTI. This warrants ultrasonography within the acute illness phase as it may reflect an underlying pathology and DMSA at 4-6 months.
– Recurrent UTI is defined as two or more episodes of pyelonephritis OR 1 pyelonephritis and one cystitis OR 3 or more cystitis. It requires USS at six weeks and DMSA at 4-6 months.
– Septicaemia is a sign of an atypical UTI. This requires USS within the acute illness as it may reflect an underlying pathology and DMSA at 4-6 months.
– Unwell 48hrs post antibiotics is a sign of an atypical UTI. This requires USS within the acute illness as may reflect underlying pathology and DMSA at 4-6 months.

Stevens-Johnson syndrome (SJS) is a type of severe skin reaction. The most common cause is certain medications such as lamotrigine, carbamazepine, allopurinol, sulphonamide antibiotics, and nevirapine.

A local exam might not help in locating the cause of the bleeding because it might be underneath the superficial structures. A thorough examination should be done under GA to accurately locate the source of bleeding.

The best answer is Polycystic Ovarian Syndrome (PCOS), supported by amenorrhea, obesity and acne. High insulin levels are indicative of PCOS and exclude Cushing syndrome (as this is associated with low insulin levels).

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.

Urine culture and sensitivity is used to diagnose a urinary tract infection (UTI). A mid-stream clean catch urine sample is the most common type of sample collected. It is important to follow the clean catch process to have accurate results from an uncontaminated sample. Urine cultures can also check for infections of the bladder or kidney.

Henoch-Schonlein purpura (HSP), also known as IgA vasculitis, is a disease of the skin, mucous membranes, and sometimes other organs that most commonly affects children. In the skin, the disease causes palpable purpura (small, raised areas of bleeding underneath the skin), often with joint pain and abdominal pain. It is an acute immunoglobulin A (IgA)-mediated disorder. The tetrad of purpura, arthritis, kidney inflammation, and abdominal pain is often observed.

Embryologically the testes are retroperitoneal structures in the posterior abdominal wall, attached to the anterolateral abdominal wall by the gubernaculum. The gubernaculum ‘pulls’ the testes through the deep inguinal ring, inguinal canal and superficial inguinal ring and over the pelvic brim. The gubernaculum is preceded by the processus vaginalis that is derived from the peritoneum anterior to the testes. The processus vaginalis pushes the muscle and fascial layers. These eventually make up the canal and the spermatic cord, into the scrotum. The gubernaculum persists as the scrotal ligament while part of the processus vaginalis remains as a bursa-like sac i.e. the tunica vaginalis testes. The testes therefore could be caught in any one of these places along its path of descending. The testes are never in the perineum.

HUS syndrome occurs mostly in children after some days of bloody diarrhoea. Damaged red blood cells also damage the kidney filtering unit and lead to sudden renal failure.

Based on the clinical presentation, the child probably has orthostatic proteinuria.

Orthostatic proteinuria occurs when the kidneys can conserve urine when the patient is recumbent, such as sleeping at night, but leak protein with standing or in exercise.
This results in early morning urine being negative for protein but late in the day urine being positive. It is mostly seen in tall thin adolescents and is benign.

Other options:
– Alport’s syndrome is a hereditary condition associated with haematuria and deafness.
– Urinary tract infections can cause proteinuria, but leucocyte esterase and nitrites would also be expected in a child of this age.
– Nephritic syndrome can be associated with proteinuria, but haematuria would also be present.
– In nephrotic syndrome, proteinuria would be present on all occasions and associated with oedema.

Proteinuria refers to an increased amount of protein excretion in urine, which should be greater than 100mg/m2 per day on a single spot urine collection. The limit is even more relaxed for infants and neonates. Proteinuria is a prominent manifestation of cystinosis, acute tubular necrosis, Fanconi syndrome, and celiac disease. Landau-Kleffner syndrome is a rare childhood convulsive disorder, associated with acquired aphasia and auditory verbal agnosia.

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 Ca and phosphates to be released from bones to buffer the acidosis causing hypercalciuria, thus precipitating calcium compounds in the kidney. Other consequences of the dRTA in children include rickets, hypokalaemia, and polyuria. While dRTA can occur as a result of various pathologies including autoimmune disease, proximal renal tubular acidosis often presents as part of Fanconi’s syndrome. One way to differentiate between the two conditions is with an acid challenge test. In proximal RTA offering the child an acid load will decrease the urinary ph whereas in distal disease the pH will be unaffected due to impairment in hydrogen ion secretion.

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

Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disorder affecting branched-chain amino acids. It is one type of organic academia. The condition gets its name from the distinctive sweet odour of affected infants’ urine, particularly prior to diagnosis, and during times of acute illness. MSUD, also known as branched-chain ketoaciduria, is an aminoacidopathy due to an enzyme defect in the catabolic pathway of the branched-chain amino acids leucine, isoleucine, and valine.

Haemolytic-uremic syndrome (HUS) is a clinical syndrome characterized by progressive renal failure that is associated with microangiopathic (nonimmune, Coombs-negative) haemolytic anaemia and thrombocytopenia. HUS is the most common cause of acute kidney injury in children. It predominantly occurs in infants and children after prodromal diarrhoea. In summer epidemics, the disease may be related to infectious causes.

Bacterial infections may include the following:
S dysenteriae
E Coli
Salmonella typhi
Campylobacter jejuni
Yersinia pseudotuberculosis
Neisseria meningitidis
S pneumonia
Legionella pneumophila
Mycoplasma species
Rickettsial infections may include Rocky Mountain spotted fever and microtatobiotes

Viral infections may include the following:
Human immunodeficiency virus (HIV)
Coxsackievirus
Echovirus
Influenza virus
Epstein-Barr virus
Herpes simplex virus
Fungal infections can include Aspergillus fumigatus.

Vaccinations may include the following:
Influenza triple-antigen vaccine
Typhoid-paratyphoid A and B (TAB) vaccine
Polio vaccine

Pregnancy-associated HUS occasionally develops as a complication of preeclampsia. Patients may progress to full-blown haemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome. Postpartum HUS usually occurs within 3 months of delivery. The prognosis is poor, with a 50-60% mortality rate, and residual renal dysfunction and hypertension occur in most patients.