Pediatric Nephrology for Adult Examinations — Advanced

This neonate has oliguria in the first day of life together with perinatal hypoxia and hypotension. Ischaemic (ischemic) acute tubular necrosis (ATN) from severe perinatal hypoperfusion is the commonest cause of early neonatal acute kidney injury (AKI) in this context. Bilateral renal agenesis presents with anhydramnios antenatally and is incompatible with life; it would be apparent earlier and not present with rising neonatal creatinine after a resuscitation event. Posterior urethral valves cause obstructive uropathy that typically presents with bladder distension, poor stream or progressive renal impairment rather than a sudden rise in creatinine immediately after perinatal hypoxia; antenatal hydronephrosis may be present. Congenital nephrotic syndrome presents later with heavy proteinuria, oedema and hypoalbuminaemia rather than immediate oliguria with perinatal hypoxia. Maternal creatinine influences neonatal values for the first 24–48 hours but would not explain progressive rise in creatinine with oliguria after hypoxic insult; the clinical context points to intrinsic AKI (ATN).

In a young boy with recurrent febrile UTIs and ultrasound evidence of hydronephrosis, a micturating cystourethrogram (MCUG/VCUG) is indicated to assess for vesicoureteric reflux and to exclude posterior urethral valves (PUV), particularly because boys are more likely to have obstructive pathology. A DMSA scan assesses renal cortical scarring but does not identify the cause of hydronephrosis or bladder outlet obstruction and is not the first investigation to define anatomic cause. Repeating the ultrasound without functional/voiding imaging delays diagnosis of reflux/PUV. Serum immunoglobulins are only indicated if there is concern about recurrent unusual infections or immunodeficiency; they do not define structural urinary tract pathology. Renal biopsy is not indicated to investigate recurrent UTIs or hydronephrosis.

In children with steroid-sensitive nephrotic syndrome who have frequent relapses despite alternate-day steroids, steroid-sparing agents are indicated to reduce steroid exposure. Oral cyclophosphamide (or levamisole in some contexts) has traditionally been used as a first-line steroid-sparing agent for frequently relapsing steroid-sensitive disease. Immediate renal biopsy is not routinely required in steroid-sensitive, typical minimal-change–type presentations before using a steroid-sparing agent. Continuing only low‑dose prednisolone perpetuates steroid toxicity and is not the preferred long-term strategy if frequent relapses occur. ACE inhibitors reduce proteinuria and are useful adjuncts but are not primary steroid-sparing immunosuppressants in this setting. Rituximab is effective for difficult steroid-dependent or frequently relapsing disease refractory to first‑line steroid‑sparing agents and is generally reserved for patients who have failed conventional agents or have contraindications.

This presentation is typical of typical (Shiga-toxin–associated) haemolytic uraemic syndrome (STEC-HUS). The mainstay of initial management is supportive care: careful fluid balance, blood pressure control, correction of electrolyte disturbances and timely initiation of renal replacement therapy if indicated. Antibiotics for diarrhoeal illness are generally avoided because some antibiotics may increase Shiga toxin release and worsen HUS risk or severity. Plasma exchange is not beneficial for typical STEC-HUS; it may be considered in rare circumstances of severe neurologic involvement but is not routine. Platelet transfusion is avoided unless there is life‑threatening bleeding or an invasive procedure is required because it may exacerbate microthrombosis. Eculizumab (complement C5 inhibitor) is indicated for complement-mediated (atypical) HUS in selected cases but is not standard immediate therapy for typical STEC-HUS.

The clinical picture (familial persistent haematuria with sensorineural hearing loss) strongly suggests Alport syndrome, which is most efficiently confirmed by genetic testing for mutations in type IV collagen genes (COL4A5, COL4A3, COL4A4). Genetic testing is preferred as first‑line because it is non‑invasive and defines inheritance, prognosis and informs family counselling. Urine culture is irrelevant if haematuria is not suspected to be infectious. Doppler ultrasound will not diagnose Alport syndrome. Complement levels are used for suspected complement-mediated glomerulonephritis, not Alport. Renal biopsy with electron microscopy can show characteristic basement membrane changes and may be used when genetic testing is inconclusive, but it is not the first‑line test if genetic testing is available.

Children with hypertension are more likely to have secondary causes than adults, the commonest being renal parenchymal disease. Initial evaluation should include urinalysis (dipstick for haematuria/protein) and urine albumin:creatinine ratio to look for renal parenchymal disease, along with renal ultrasound and basic blood tests. Ambulatory BP monitoring can help confirm hypertension but does not evaluate underlying secondary causes. Starting ACE inhibitor therapy without basic investigations and baseline renal function/urinalysis is not appropriate. Renal biopsy is not a first‑line test unless urinalysis, imaging and bloods point to intrinsic glomerular disease requiring histology. Plasma aldosterone/renin testing is reserved for suspected primary hyperaldosteronism or renovascular hypertension and is not the initial screen in a child with suspected renal parenchymal disease.

Children with hypertension are more likely to have secondary causes than adults, the commonest being renal parenchymal disease. Initial evaluation should include urinalysis (dipstick for haematuria/protein) and urine albumin:creatinine ratio to look for renal parenchymal disease, along with renal ultrasound and basic blood tests. Ambulatory BP monitoring can help confirm hypertension but does not evaluate underlying secondary causes. Starting ACE inhibitor therapy without basic investigations and baseline renal function/urinalysis is not appropriate. Renal biopsy is not a first‑line test unless urinalysis, imaging and bloods point to intrinsic glomerular disease requiring histology. Plasma aldosterone/renin testing is reserved for suspected primary hyperaldosteronism or renovascular hypertension and is not the initial screen in a child with suspected renal parenchymal disease.

The child has acute urinary retention causing post‑renal obstructive AKI. The most important immediate step is prompt decompression of the urinary tract by bladder catheterisation to relieve obstruction and restore urine flow. Peritoneal dialysis may be required later if obstruction causes sustained renal failure or complications, but immediate decompression takes priority. Broad-spectrum antibiotics are indicated if there is evidence of infection but are not the immediate manoeuvre to relieve obstruction. Furosemide is not appropriate in the presence of mechanical obstruction and will not relieve retention. Renal biopsy is irrelevant for acute obstructive presentation.

Post‑streptococcal glomerulonephritis typically presents 1–3 weeks after a streptococcal pharyngitis or skin infection with nephritic features and is commonly associated with low serum complement C3 levels (which usually recover over 6–8 weeks). Elevated CRP is non‑specific and not diagnostic. A positive ANA suggests autoimmune disease such as lupus, not classical post‑streptococcal GN. Low IgG would suggest hypogammaglobulinaemia and is unrelated. A positive urine culture indicates urinary infection rather than post‑streptococcal GN; it would not support that diagnosis.

Children with nephrotic syndrome have an increased thrombotic risk due to hypercoagulability, but the presence of a central venous catheter is a particularly strong, modifiable risk factor for venous thrombosis. Corticosteroid therapy is commonly used but is not the dominant determinant of thrombotic risk. Recurrent UTIs are not a major thrombotic risk factor. Younger age (under 2 years) tends to be associated with lower thrombotic risk compared with adolescents; older children and adolescents have higher thrombotic risk. ACE inhibitor therapy is not associated with increased thrombotic risk.