# Nephrolithiasis in Children > Nephrolithiasis in children for NEET-PG Paediatrics: stone composition, hypercalciuria, imaging, full metabolic workup and medical management. - Canonical URL: https://prepelephant.com/topics/neet-pg/paediatrics/nephrolithiasis-children - Exam / course: NEET-PG · Subject: Paediatrics - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Nephrolithiasis in Children", PrepElephant, https://prepelephant.com/topics/neet-pg/paediatrics/nephrolithiasis-children ## Direct answer Nephrolithiasis in children is far less common than in adults, but a much higher proportion of paediatric stones have an identifiable metabolic cause, which is why every child with a stone deserves a metabolic evaluation, not just symptom relief. Calcium oxalate stones dominate (roughly three-quarters), and hypercalciuria is the single most common metabolic abnormality found. Presentation ranges from classic colicky flank pain with vomiting to non-specific irritability in infants, with microscopic haematuria in up to 90 per cent. Ultrasound is the first-line imaging test; a non-contrast CT is reserved for doubtful cases. Management pairs urologic relief of obstruction with fluid, citrate, and cause-specific medical therapy. ## What you must remember - **Composition rules:** calcium oxalate is the commonest stone; struvite (magnesium ammonium phosphate) forms in alkaline urine from urease-splitting organisms such as Proteus and grows into staghorn calculi; uric acid stones complicate tumour lysis and Lesch-Nyhan syndrome; cystine stones come from cystinuria. - **Hypercalciuria is the commonest metabolic abnormality:** urinary calcium above 4 mg/kg/day (or an elevated spot urine calcium-to-creatinine ratio) after excluding hypercalcaemia, hyperparathyroidism and vitamin D excess. - **Clinical picture:** colicky abdominal or flank pain radiating to the groin, vomiting, gross or microscopic haematuria; infants and toddlers may present with only screaming feeds, irritability or feeding refusal. - **Imaging ladder:** ultrasound first — no radiation, shows the stone, hydronephrosis and nephrocalcinosis; plain KUB misses radiolucent stones; low-dose non-contrast CT is the most sensitive but is kept in reserve in children. - **Every child gets a metabolic workup:** stone analysis (the single most valuable test if a stone is passed), 24-hour urine for calcium, oxalate, urate, citrate and cystine, plus serum calcium, electrolytes, uric acid and creatinine. - **Classic syndrome anchors:** distal renal tubular acidosis gives calcium phosphate stones with nephrocalcinosis and a urinary pH that refuses to fall below 5.5; primary hyperoxaluria causes recurrent stones and early renal failure; cystinuria shows hexagonal crystals and a positive cyanide-nitroprusside screen. - **Medical therapy:** generous fluid intake round the clock, dietary salt restriction (sodium drives urinary calcium), potassium citrate for hypocitraturia and calcium stones, thiazides for persistent hypercalciuria — calcium restriction is counterproductive. - **Indian context:** hot summers, low fluid intake and the north-western stone belt make paediatric stones a real entity in Indian practice; a first stone after a summer of poor intake still warrants the full metabolic workup. ## The workup, step by step Walk a six-year-old with acute left flank pain and vomiting through the pathway. First, confirm the stone and its consequences: urinalysis (haematuria, crystals, urine pH), urine culture, and an ultrasound showing a 6 mm stone at the vesicoureteric junction with mild hydronephrosis. Analgesia (an NSAID or intranasal/opioid analgesia per local practice) and hydration follow; a stone under 10 mm in a well child with controlled pain can often be managed expectantly with straining every void. Now the part that separates paediatric from adult practice: the cause hunt, four to six weeks after the acute episode so that pain, vomiting and intravenous fluids no longer distort the results. Retrieve the strained stone for analysis. Collect a 24-hour urine on a normal diet plus a blood sample. Suppose the results show urinary calcium of 5 mg/kg/day with a normal serum calcium — idiopathic hypercalciuria, the workhorse diagnosis. The prescription is fluids to keep urine dilute, salt restriction, adequate dietary calcium, potassium citrate, and a thiazide if stones recur. Had the urine pH been persistently high with hypokalaemia and a positive acid load test, distal RTA would demand citrate and bicarbonate for life; hexagonal crystals would have sent you to the cyanide-nitroprusside test and cystine-saturating therapy with alkali. ## How the exam frames it Three recurring traps. First, the diet question: restricting calcium in a child with calcium stones worsens oxalate absorption and stone risk — the correct answer is salt restriction, which lowers urinary calcium. Second, the staghorn question: a large calculus moulding the renal pelvis means infection with a urease-producing organism until proven otherwise, and management is percutaneous nephrolithotomy, not expectant therapy. Third, the pH question set: stones that form in alkaline urine (struvite, calcium phosphate with distal RTA) versus acidic urine (uric acid, cystine) is a favourite one-liner in image-based stems. A child with stones, short stature and metabolic acidosis should make you say distal RTA out loud before looking at the options. ## Frequently asked questions ### What is the first-line imaging for a suspected renal stone in a child? Ultrasound, because it avoids radiation and detects stones, hydronephrosis and nephrocalcinosis; low-dose non-contrast CT is reserved for equivocal cases. ### Which single test is most valuable if the child passes the stone? Stone analysis, since it directly identifies the underlying metabolic abnormality and directs specific preventive therapy. ### How is hypercalciuria defined in children? Urinary calcium excretion above 4 mg/kg/day on a 24-hour collection, or an elevated age-adjusted spot urine calcium-to-creatinine ratio, with normal serum calcium. ### Which stone type forms staghorn calculi and why? Struvite, because urease-producing organisms such as Proteus split urea, alkalinise the urine and allow magnesium ammonium phosphate to fill the renal pelvis. ### Is dietary calcium restriction advised in children with calcium stones? No; adequate calcium binds intestinal oxalate, and restriction increases oxalate absorption and recurrence — salt restriction plus fluids is the dietary answer.