Paediatric: Renal Endocrine

• Kidneys and urinary tract: Urinary Tract Infection | Imaging After a UTI | Vesicoureteric Reflux and Congenital Anomalies | Nephrotic Syndrome | Nephritis and Haematuria | Haemolytic Uraemic Syndrome | AKI and CKD in Children | Bedwetting and Daytime Wetting
• Diabetes: Type 1 Diabetes in Children | Living With Type 1 Diabetes | Diabetic Ketoacidosis in Children | Hypoglycaemia in Children | Type 2 and Other Diabetes
• Other endocrine: Thyroid Disorders | Congenital Adrenal Hyperplasia | Adrenal Insufficiency | Disorders of Sex Development | Thirst and Passing Lots of Urine | Calcium Problems
• Revision: Drug Reference Table | Spot the Diagnosis | Exam-style Scenarios | Key Points | Guidelines and Further Reading

🧪 Kidneys, urinary tract and hormones in children — UTIs are common and easily missed in babies (who have no specific symptoms), and repeated infections can scar the kidneys. Type 1 diabetes is often diagnosed late — around a quarter of children present in DKA, which kills through cerebral oedema. Think "4 Ts": Toilet, Thirsty, Tired, Thinner — and check a finger-prick glucose the same day.
Your four questions for every child: Could this be a UTI (test the urine in any unwell child without a clear cause)? Could this be diabetes (check glucose and ketones)? Is the child growing and developing normally? Is there a risk of adrenal crisis (CAH, steroids)?

Urinary Tract Infection

• Features by age:
  • Babies under 3 months — fever, vomiting, lethargy, irritability, poor feeding, faltering growth, jaundice, sepsis.
  • Toddlers — fever, vomiting, abdominal pain, poor feeding, smelly urine.
  • Older children — frequency, dysuria, wetting, abdominal or loin pain, fever.
• Who to test — any infant or child with symptoms suggesting UTI, unexplained fever of 38 °C or more (test within 24 hours), or an alternative infection not responding.
• Collecting urine — clean-catch sample is best; urine collection pads if not possible; catheter or suprapubic aspiration if needed (unwell infants).
• Testing (NICE NG224):
  • Under 3 months — refer immediately to paediatrics; urgent microscopy and culture; IV antibiotics.
  • 3 months to 3 years — urgent microscopy and culture (dipstick less reliable); treat if microscopy positive for bacteria (or clinically likely).
  • 3 years and over — dipstick:
    • Nitrite positive (with or without leucocytes) — treat; send culture.
    • Leucocytes only — send culture; treat if there's clinical evidence of UTI.
    • Both negative — UTI unlikely.
• Upper UTI (pyelonephritis) — fever of 38 °C or more with bacteriuria, or loin pain or tenderness. Higher risk of kidney scarring.
• Treatment (NICE NG224):
  • Lower UTI (over 3 months) — oral trimethoprim or nitrofurantoin for 3 days (or per sensitivities); amoxicillin if known sensitive.
  • Upper UTI — oral cefalexin or co-amoxiclav for 7–10 days; IV (e.g. co-amoxiclav, cefuroxime, ceftriaxone or gentamicin) if severe, under 3 months, or unable to take oral.
  • Review if no improvement within 48 hours.
  • Fluids; paracetamol or ibuprofen; treat constipation (common contributor).
• Prevention — good fluid intake, regular voiding, treat constipation, avoid bubble baths; antibiotic prophylaxis only in selected children with recurrent UTIs (specialist).

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Imaging After a UTI

• Atypical UTI — seriously ill or septicaemic, poor urine flow, abdominal or bladder mass, raised creatinine, no response to antibiotics within 48 hours, infection with a non-E. coli organism.
• Recurrent UTI — two or more upper UTIs; or one upper and one or more lower; or three or more lower UTIs.

• Ultrasound — kidney size, hydronephrosis, bladder.
• DMSA scan — shows renal scarring (done 4–6 months after infection).
• MCUG (micturating cystourethrogram) — shows vesicoureteric reflux and posterior urethral valves (needs a catheter; antibiotic cover).

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Vesicoureteric Reflux and Congenital Anomalies

• Vesicoureteric reflux (VUR) — urine flows back up from the bladder into the ureters and kidneys:
  • Graded I (into the ureter only) to V (gross dilatation).
  • Runs in families; often found after a UTI or antenatal hydronephrosis.
  • With infection, can cause renal scarring (reflux nephropathy) — hypertension and CKD later.
  • Management — most mild reflux resolves with growth; prompt treatment of UTIs; antibiotic prophylaxis in selected children; surgery (endoscopic injection or reimplantation) for severe reflux with breakthrough infections.
• Antenatal hydronephrosis — common finding on scans; most mild and resolve. Postnatal ultrasound; consider antibiotic prophylaxis for significant dilatation.
• Posterior urethral valves — the commonest cause of urinary obstruction in boys:
  • Antenatal — bilateral hydronephrosis, thick-walled bladder, oligohydramnios (pulmonary hypoplasia in severe cases).
  • After birth — poor urine stream, palpable bladder, UTI, AKI.
  • Urgent catheter; endoscopic valve ablation; long-term kidney follow-up (CKD risk).
• Pelviureteric junction obstruction — hydronephrosis without ureteric dilatation; MAG3 renogram; pyeloplasty if function is falling.
• Multicystic dysplastic kidney — a non-functioning kidney of cysts; usually shrinks; check the other kidney.
• Other — duplex kidneys, horseshoe kidney (Turner syndrome), renal agenesis, polycystic kidney disease (ARPKD, ADPKD), bladder exstrophy.

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Nephrotic Syndrome

• Definition — heavy proteinuria (urine protein:creatinine ratio over 200 mg/mmol, or 3+ on dipstick), low albumin (under 25 g/L) and oedema.
• Who — mostly children aged 2–5; boys more than girls; more common in South Asian children.
• Cause — about 90% of children have minimal change disease, which is usually steroid-sensitive.
• Features:
  • Periorbital swelling (often first, worse in the mornings — mistaken for allergy).
  • Swollen legs, scrotum or labia; ascites; pleural effusions.
  • Frothy urine.
  • Weight gain; reduced urine output; abdominal pain.
• Tests — urine dipstick and PCR; albumin; U&E; FBC; lipids (raised); complement; varicella serology; BP; hepatitis B and C, HIV in some.
• Treatment (steroid-sensitive nephrotic syndrome):
  • Oral prednisolone 60 mg/m² daily (maximum 60 mg) for 4 weeks, then 40 mg/m² on alternate days (maximum 40 mg) for 4 weeks, then stop.
  • Most respond (protein-free urine) within 2 weeks.
  • Salt restriction; fluid restriction only if severe oedema; diuretics with care (risk of hypovolaemia).
  • Penicillin V prophylaxis while nephrotic (pneumococcal infection risk).
  • Pneumococcal vaccine; check varicella immunity (chickenpox can be severe on steroids).
  • Monitor urine at home with dipsticks to detect relapses.
• Complications:
  • Infection — spontaneous bacterial peritonitis (pneumococcus), cellulitis, sepsis (loss of immunoglobulins, steroids).
  • Hypovolaemia — despite oedema: abdominal pain, cold peripheries, tachycardia, raised haematocrit — albumin infusion.
  • Thrombosis — loss of anticoagulant proteins (renal vein, cerebral venous sinus, DVT).
  • High cholesterol; AKI; steroid side effects (behaviour, weight, BP, growth).
• Relapses are common (about 80%) — repeat steroid course. Frequent relapses or steroid dependence — steroid-sparing drugs (levamisole, mycophenolate, tacrolimus, cyclophosphamide, rituximab).
• Refer for biopsy (atypical) if — under 1 or over 12, steroid-resistant (no response after 4 weeks), haematuria, hypertension, low complement, raised creatinine — consider FSGS, membranous, MPGN, lupus.
• Congenital nephrotic syndrome (under 3 months) — genetic (e.g. Finnish type).

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Nephritis and Haematuria

• Nephritic syndrome — haematuria (often cola-coloured), proteinuria, hypertension, oedema, reduced urine output and rising creatinine.
• Causes in children:
  • Post-streptococcal glomerulonephritis — 1–3 weeks after a sore throat (or 3–6 weeks after impetigo); low C3, raised ASOT; supportive care (fluid and salt restriction, diuretics, BP control); good prognosis.
  • IgA vasculitis (HSP) nephritis — after the rash; monitor BP and urine for 6 months.
  • IgA nephropathy — visible haematuria 1–2 days after a sore throat.
  • Lupus nephritis; ANCA vasculitis; HUS; Alport syndrome.
• Haematuria — other causes — UTI, trauma, stones (hypercalciuria), sickle cell, coagulopathy, Wilms tumour, exercise, thin basement membrane disease; red urine without blood — beetroot, rifampicin, myoglobin.
• Refer — haematuria with proteinuria, hypertension, raised creatinine, or persistent invisible haematuria.
• See the Glomerular Disease chapter.

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Haemolytic Uraemic Syndrome

• What it is: A thrombotic microangiopathy — triad of microangiopathic haemolytic anaemia, low platelets and AKI.
• Cause — usually Shiga toxin-producing E. coli (STEC, O157) — from undercooked beef, petting farms, contaminated food; mostly children under 5. Rarely pneumococcal or atypical (complement) HUS.
• Features:
  • Bloody diarrhoea and abdominal pain, then 5–10 days later:
  • Pallor, tiredness, irritability.
  • Reduced urine output, oedema, hypertension.
  • Bruising, petechiae.
  • Seizures, confusion, stroke (CNS involvement).
• Tests — FBC (anaemia, low platelets), blood film (schistocytes), raised LDH, low haptoglobin, negative DAT, U&E (AKI), stool culture and STEC PCR.
• Management:
  • Supportive — careful fluid balance, electrolytes, BP control, blood transfusion (avoid platelets unless bleeding).
  • Dialysis in about half.
  • Avoid antibiotics and antimotility drugs in STEC diarrhoea (may increase toxin release).
  • Eculizumab for atypical HUS.
  • Notify UKHSA; exclude from nursery until two negative stools.
• Outcome — most recover; some develop CKD and hypertension (follow-up).

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AKI and CKD in Children

• AKI causes — dehydration (gastroenteritis), sepsis, HUS, nephrotoxic drugs (NSAIDs, aminoglycosides), glomerulonephritis, obstruction (posterior urethral valves), after cardiac surgery.
• AKI management — restore fluid status, stop nephrotoxins, treat hyperkalaemia, dialysis if needed (see the AKI chapter — doses by weight).
• CKD causes in children — congenital anomalies of the kidney and urinary tract (CAKUT) — the commonest (dysplasia, obstruction, reflux nephropathy); glomerular disease (FSGS); inherited (polycystic kidneys, cystinosis, nephronophthisis, Alport).
• CKD effects in children — poor growth (growth hormone may help), anaemia, renal bone disease (rickets), hypertension, developmental and school problems, acidosis; transplant is the best treatment for kidney failure.
• Hypertension in children — usually secondary in young children (renal parenchymal disease, renal artery stenosis, coarctation, endocrine); measure with the right cuff size and use centile charts.

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Bedwetting and Daytime Wetting

• Nocturnal enuresis (bedwetting) — common: about 1 in 6 five-year-olds, 1 in 20 ten-year-olds. Usually not treated under 5. More common in boys; strong family history.
• Primary (never been dry for 6 months) — usually from a combination of large night-time urine volumes, small bladder capacity, and not waking to the sensation of a full bladder.
• Secondary (wetting after 6 months of dryness) — look for a cause:
  • UTI; constipation (very common).
  • Diabetes mellitus (check urine glucose); diabetes insipidus.
  • Emotional stress — new sibling, school, family breakdown; abuse.
  • Obstructive sleep apnoea; neurological problems (spinal).
• Assessment (NICE CG111) — pattern, daytime symptoms, fluid intake, toileting, bowel habit, emotional factors; urine dipstick (glucose, infection); examine the spine, genitalia and abdomen; bladder diary.
• Management:
  • Reassure — common and not the child's fault; avoid punishment.
  • Fluids — adequate during the day (6–8 drinks), avoid caffeine and fizzy drinks, reduce drinks in the hour before bed.
  • Toilet regularly in the day and just before bed; easy access at night.
  • Reward systems for agreed behaviours (drinking well, using the toilet before bed) — not for dry nights.
  • Treat constipation.
  • Enuresis alarm — first-line treatment for motivated children and families (from about 5–7) — works within 4 weeks; continue until 2 weeks of dry nights.
  • Desmopressin — if an alarm is unsuitable or hasn't worked, or for short-term control (sleepovers, school trips) in children over 5. Restrict fluids from 1 hour before to 8 hours after the dose (risk of hyponatraemia).
  • Combination or anticholinergics (oxybutynin) in specialist care.
• Daytime wetting — overactive bladder (urgency, holding manoeuvres), voiding postponement, constipation, UTI, giggle incontinence; constant wetting in a girl with normal voiding suggests an ectopic ureter. Refer if persistent.

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Type 1 Diabetes in Children

• The commonest form of diabetes in children in the UK; autoimmune destruction of insulin-producing beta cells. Peak onset at 5–7 years and around puberty.
• Symptoms — the "4 Ts":
  • Toilet — passing lots of urine, new bedwetting, heavy nappies.
  • Thirsty.
  • Tired.
  • Thinner — weight loss.
  • Also — recurrent infections (thrush), blurred vision, behaviour change.
• DKA features — vomiting, abdominal pain, deep sighing breathing (Kussmaul), ketotic breath, dehydration, drowsiness.
• Diagnosis — a child with symptoms and a random glucose over 11 mmol/L. Check a finger-prick glucose the same day and refer the same day to the paediatric diabetes team (don't wait for a fasting test or HbA1c).
• Tests — glucose, blood ketones, venous gas, U&E, HbA1c; autoantibodies (GAD, IA-2, ZnT8); coeliac serology and TFTs (associated autoimmune diseases).
• Treatment (NICE NG18):
  • Insulin — multiple daily injections (basal–bolus: long-acting once daily plus rapid-acting with meals) or an insulin pump.
  • Hybrid closed-loop systems (pump plus continuous glucose monitor with an algorithm) — recommended by NICE for children and young people with type 1 diabetes.
  • Continuous glucose monitoring (CGM) for all.
  • Carbohydrate counting to match insulin to meals.
  • HbA1c target 48 mmol/mol or lower (as long as it doesn't cause problematic hypoglycaemia); time in range on CGM.
  • Education — child, family and school; multidisciplinary team (nurse, dietitian, psychologist).

⚠️ Safety Pearl: A child who is drinking more, wetting the bed again, and losing weight needs a finger-prick glucose today. Delayed diagnosis leads to DKA — refer the same day, don't send for a fasting test.

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Living With Type 1 Diabetes

• Hypoglycaemia (glucose under 4 mmol/L):
  • Symptoms — shaky, sweaty, pale, hungry, irritable, poor concentration, behaviour change; then confusion, seizures, unconsciousness.
  • Mild — fast-acting glucose (e.g. 0.3 g/kg — glucose tablets, juice), recheck in 15 minutes, then a longer-acting snack.
  • Severe (can't swallow safely) — glucagon IM or SC (or nasal glucagon); in hospital — IV 10% glucose 2 mL/kg.
• Sick day rules — never stop insulin; check glucose and blood ketones more often; extra rapid-acting insulin if ketones raised; fluids; seek help if vomiting or ketones over 3 mmol/L.
• Exercise — check glucose before, during and after; extra carbohydrate or reduced insulin; delayed hypoglycaemia overnight.
• School — individual healthcare plan; trained staff; access to snacks, glucose testing and insulin.
• Annual screening — thyroid function, coeliac serology, retinopathy (from 12), urine ACR (from 12), BP, growth and puberty, foot and injection site checks.
• Adolescence — insulin resistance in puberty, risk-taking, alcohol (delayed hypoglycaemia), eating disorders (insulin omission for weight loss), mental health, driving rules; transition to adult services.
• Psychological support — depression, anxiety and "diabetes distress" are common.

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Diabetic Ketoacidosis in Children

• Diagnosis (BSPED) — acidosis (venous pH under 7.3 or bicarbonate under 15 mmol/L) plus ketonaemia (blood ketones over 3 mmol/L) or ketonuria, in a child with diabetes (glucose usually over 11).
• Severity — mild (pH 7.2–7.29), moderate (7.1–7.19), severe (under 7.1).
• Management (follow the BSPED DKA guideline and calculator):
  • ABC; senior help; weigh the child.
  • Shocked (poor perfusion, low BP) — 10 mL/kg 0.9% saline bolus over 15 minutes, repeated if needed (up to 40 mL/kg) — discuss with PICU.
  • Not shocked — a 10 mL/kg bolus over 60 minutes may be given; then calculate fluids:
    • Deficit — 5% of body weight (pH 7.1 or above) or 10% (pH under 7.1), replaced slowly over 48 hours, plus maintenance.
    • Fluid — 0.9% sodium chloride with potassium chloride 40 mmol/L (unless anuric or high potassium); add glucose (5–10%) when glucose falls below 14 mmol/L.
  • Insulin — IV infusion of soluble insulin at 0.05–0.1 units/kg/hour, started 1–2 hours after IV fluids begin. No insulin bolus. Continue long-acting insulin if already on it.
  • Monitoring — hourly glucose, observations, neurological state and fluid balance; blood ketones and gas 1–2 hourly; U&E and potassium regularly; ECG monitoring.
  • Avoid bicarbonate (except in specific cardiac arrest situations).
  • Look for and treat the trigger (missed insulin, infection).
  • Switch to subcutaneous insulin when ketones under 1 mmol/L, pH normal, and eating and drinking.
• Cerebral oedema — the main cause of death in childhood DKA (higher risk in young children, new diagnosis, severe acidosis, low CO2, rapid fluid or insulin, a falling sodium):
  • Warning signs — headache, irritability, confusion, slowing heart rate, rising BP, falling GCS, abnormal breathing, incontinence, pupil changes.
  • Treat immediately — hypertonic saline (2.7% or 3%, 2.5–5 mL/kg) or mannitol (0.5–1 g/kg) over 15 minutes; reduce fluids; raise the head of the bed; PICU; CT after treatment.
• Other complications — hypokalaemia, hypoglycaemia, aspiration, VTE (especially with central lines).

💡 Clinical Pearl: Children with DKA are dehydrated, but rehydration is slow (over 48 hours) and insulin is started 1–2 hours after fluids — both to reduce the risk of cerebral oedema. Headache or a slowing pulse during treatment is cerebral oedema until proven otherwise.

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Hypoglycaemia in Children

• In children without diabetes, low glucose (under 3.0 mmol/L) needs investigation.
• Causes:
  • Ketotic hypoglycaemia — the commonest: thin young children (18 months to 5 years) after a period of fasting or illness; ketones high; resolves with age. Avoid long fasts; bedtime snacks.
  • Adrenal insufficiency (CAH, Addison's, steroid withdrawal); growth hormone deficiency; hypopituitarism.
  • Metabolic disorders — MCADD (fatty acid oxidation — low ketones; screened at birth), glycogen storage diseases (large liver), galactosaemia.
  • Hyperinsulinism — congenital, insulinoma, factitious (insulin given by a carer — low C-peptide).
  • Poisoning — alcohol, beta-blockers, sulfonylureas, salicylates.
  • Sepsis; liver failure; malnutrition.
• Hypo screen — take blood during the hypoglycaemia (before treatment if possible): glucose, ketones, insulin, C-peptide, cortisol, growth hormone, lactate, ammonia, free fatty acids, acylcarnitines, plus the first urine (organic acids, ketones, toxicology).
• Treatment — oral glucose if alert; IV 10% glucose 2 mL/kg then an infusion if not; glucagon IM (not in adrenal insufficiency or fatty acid oxidation disorders where it may not work); hydrocortisone if adrenal insufficiency suspected.

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Type 2 and Other Diabetes

• Type 2 diabetes — increasing with childhood obesity; more common in South Asian and Black children, girls, family history; acanthosis nigricans; PCOS. Treatment — lifestyle, metformin, then insulin or GLP-1 agonists; screen for complications at diagnosis (higher early complication rates than type 1).
• MODY (maturity-onset diabetes of the young) — autosomal dominant, strong family history, onset under 25, non-obese, no autoantibodies, low insulin needs; HNF1A MODY responds to sulfonylureas; GCK MODY (mild stable hyperglycaemia) needs no treatment.
• Neonatal diabetes (under 6 months) — genetic (e.g. KCNJ11 — treat with sulfonylureas); always test genetics.
• Cystic fibrosis-related diabetes; steroid-induced diabetes; diabetes after pancreatitis.

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Thyroid Disorders

• Congenital hypothyroidism:
  • About 1 in 2,500 babies; usually thyroid dysgenesis (absent, small or ectopic gland) or dyshormonogenesis.
  • Detected by newborn blood spot screening (raised TSH).
  • Untreated — prolonged jaundice, poor feeding, constipation, large tongue, umbilical hernia, hoarse cry, dry skin, hypotonia, delayed development and learning disability.
  • Start levothyroxine within the first 2 weeks — normal development if treated early.
• Acquired hypothyroidism — usually autoimmune (Hashimoto's); more common in girls, Down syndrome, Turner syndrome, type 1 diabetes: slowing growth (with weight gain), tiredness, constipation, declining school performance, goitre, delayed (or sometimes early) puberty. Levothyroxine.
• Hyperthyroidism — usually Graves' disease in teenagers: weight loss, tremor, anxiety, poor sleep, heat intolerance, tall stature, goitre, eye signs, falling school performance. Carbimazole (block-and-replace), beta-blocker; radioiodine or surgery later.
• Neonatal thyrotoxicosis — from maternal TSH-receptor antibodies (Graves'): irritability, tachycardia, poor weight gain; temporary.

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Congenital Adrenal Hyperplasia

• What it is: An autosomal recessive enzyme deficiency in cortisol production — over 90% 21-hydroxylase deficiency. Low cortisol (and often low aldosterone) drives high ACTH, so the adrenals overproduce androgens.
• Presentation:
  • Girls — ambiguous (virilised) genitalia at birth (enlarged clitoris, fused labia) with a normal womb and ovaries (46,XX).
  • Boys — normal genitalia, so often missed until a salt-wasting crisis at 1–3 weeks: vomiting, poor feeding, weight loss, dehydration, collapse.
  • Salt-wasting crisis bloods — low sodium, high potassium, low glucose, metabolic acidosis.
  • Non-salt-wasting (simple virilising) — early pubic hair, rapid growth, advanced bone age, enlarged penis or clitoris in childhood.
  • Non-classical CAH — later presentation: early pubarche, hirsutism, irregular periods (mimics PCOS).
• Diagnosis — raised 17-hydroxyprogesterone; electrolytes; karyotype; pelvic ultrasound.
• Treatment:
  • Hydrocortisone (glucocorticoid replacement, and suppression of ACTH and androgens).
  • Fludrocortisone (mineralocorticoid) and salt supplements in infancy (salt-wasting).
  • Salt-wasting crisis — IV fluids (0.9% saline with glucose), IV or IM hydrocortisone, treat hyperkalaemia and hypoglycaemia.
  • Sick day rules — double or triple hydrocortisone during illness; emergency IM hydrocortisone injection kit; steroid emergency card.
  • Monitor growth, bone age, 17-OHP and androgens.
  • Multidisciplinary care for genitalia (surgery decisions are complex).

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Adrenal Insufficiency

• Causes in children:
  • CAH (the commonest primary cause).
  • Long-term steroids (including high-dose inhaled steroids) — suppression of the adrenals; risk on sudden stopping or during illness.
  • Autoimmune Addison's disease (with other autoimmune conditions), adrenoleukodystrophy (boys — with neurological decline), adrenal haemorrhage (meningococcal sepsis — Waterhouse–Friderichsen).
  • Hypopituitarism (craniopharyngioma, after brain tumour treatment).
• Features — tiredness, poor weight gain, vomiting, abdominal pain, hypoglycaemia, low BP; hyperpigmentation (primary); adrenal crisis with illness (shock, low sodium, high potassium, low glucose).
• Emergency treatment — IM or IV hydrocortisone — under 1 year 25 mg, 1–5 years 50 mg, 6 years and over 100 mg; IV fluids and glucose.
• Sick day rules — double or triple the usual hydrocortisone during fever or illness; IM injection if vomiting; steroid emergency card; extra cover for surgery.

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Disorders of Sex Development

• What they are: Conditions where chromosomal, gonadal or anatomical sex is atypical — e.g. ambiguous genitalia at birth.
• Causes:
  • 46,XX — CAH (the commonest cause of ambiguous genitalia), maternal androgens.
  • 46,XY — androgen insensitivity syndrome (complete — female appearance; partial — ambiguous), 5-alpha reductase deficiency, testicular dysgenesis.
  • Sex chromosome DSD — Turner (45,X), Klinefelter (47,XXY), 45,X/46,XY mosaicism.
• Signs at the newborn examination — ambiguous genitalia, bilateral impalpable testes, severe hypospadias with undescended testes, clitoral enlargement, labial fusion.
• Management:
  • Urgent specialist assessment — a medical priority (exclude salt-wasting CAH — check electrolytes and glucose).
  • Don't guess the baby's sex; explain that tests are needed; support parents (birth registration can be delayed).
  • Tests — karyotype (rapid), 17-OHP, electrolytes, hormones, pelvic ultrasound.
  • Multidisciplinary team (endocrinology, urology, genetics, psychology).

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Thirst and Passing Lots of Urine

• Causes:
  • Diabetes mellitus — always check glucose first.
  • Habitual (psychogenic) polydipsia — toddlers who drink lots of juice or water; concentrate urine overnight.
  • Diabetes insipidus:
    • Cranial — brain tumours (craniopharyngioma, germinoma), Langerhans cell histiocytosis, head injury, after neurosurgery.
    • Nephrogenic — genetic (X-linked, boys), lithium, hypercalcaemia, hypokalaemia.
  • CKD (poor concentrating ability); renal tubular disorders (Fanconi, Bartter).
  • Hypercalcaemia; hypokalaemia.
  • UTI (frequency rather than polyuria).
• Tests — glucose, U&E, calcium, plasma and urine osmolality (early-morning sample); water deprivation test (specialist); MRI pituitary if cranial DI.

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Calcium Problems

• Hypocalcaemia:
  • Neonates — prematurity, infant of a diabetic mother, maternal vitamin D deficiency, DiGeorge syndrome (22q11 — with heart defects, cleft palate, immune problems).
  • Older children — vitamin D deficiency (rickets), hypoparathyroidism, CKD, pseudohypoparathyroidism (short fourth metacarpals).
  • Features — jitteriness, tetany, carpopedal spasm, seizures, laryngospasm, long QT.
  • Treatment — IV calcium gluconate (slowly, with ECG monitoring) for symptoms; oral calcium and vitamin D (or alfacalcidol).
• Hypercalcaemia — rare: Williams syndrome (infants), immobilisation, malignancy, vitamin D excess, hyperparathyroidism; vomiting, constipation, polyuria.
• Rickets — see the Growth, Development and Nutrition chapter.

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Drug Reference Table

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Spot the Diagnosis

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Exam-style Scenarios

1. A 4-month-old has a fever of 39 °C for 2 days with no focus. A catheter urine shows many white cells and Gram-negative rods. She responds to IV antibiotics within 24 hours.
Answer: Upper UTI in an infant under 6 months, responding well.

• Complete 7–10 days (switch to oral when well).
• Renal ultrasound within 6 weeks.
• If atypical or recurrent — ultrasound during illness, DMSA and MCUG.

2. A 4-year-old has had puffy eyes for a week and swollen legs. Urine protein 4+, albumin 14 g/L, BP normal, no haematuria.
Answer: Nephrotic syndrome, probably minimal change disease.

• Prednisolone 60 mg/m² for 4 weeks, then 40 mg/m² on alternate days for 4 weeks.
• Penicillin V prophylaxis; salt restriction; check varicella immunity; pneumococcal vaccine.
• Watch for hypovolaemia, infection and thrombosis; home urine dipsticks for relapse.

3. A 9-year-old has been drinking a lot and wetting the bed for 3 weeks, and has lost 3 kg. Finger-prick glucose 21 mmol/L; blood ketones 1.2.
Answer: New type 1 diabetes without DKA.

• Same-day referral to the paediatric diabetes team.
• Start subcutaneous insulin; education; CGM.
• Coeliac serology and TFTs.

4. A 6-year-old with new diabetes is in DKA (pH 7.05, bicarbonate 6, ketones 6). She weighs 20 kg and is not shocked.
Answer: Severe DKA.

• Fluids: 10% deficit (2 L) over 48 hours plus maintenance, with potassium 40 mmol/L (BSPED calculator); possible initial 10 mL/kg bolus over 60 minutes.
• Insulin infusion 0.05–0.1 units/kg/hour started 1–2 hours after fluids; no bolus; no bicarbonate.
• Hourly neurological observations; act immediately on headache or bradycardia (cerebral oedema).

5. A 12-day-old boy has vomited for 2 days and is lethargic. Sodium 122, potassium 7.4, glucose 2.3. His genitals look normal.
Answer: Salt-wasting congenital adrenal hyperplasia (adrenal crisis).

• IV fluids (0.9% saline with glucose); treat hypoglycaemia; IV hydrocortisone 25 mg.
• Bloods for 17-OHP, cortisol and renin before treatment if possible; ECG and treat hyperkalaemia.
• Long term: hydrocortisone, fludrocortisone, salt; sick day rules and emergency kit.

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Key Points

• Test the urine in any unexplained fever; under 3 months — refer immediately.
• Under 3 years — microscopy and culture; 3 and over — dipstick (nitrites are most useful).
• Lower UTI: 3 days of trimethoprim or nitrofurantoin; upper UTI: 7–10 days of cefalexin or co-amoxiclav.
• Imaging after UTI depends on age, atypical features and recurrence (ultrasound, DMSA, MCUG).
• Posterior urethral valves: boys with poor stream and bilateral hydronephrosis — catheterise.
• Nephrotic syndrome in children is usually minimal change and steroid-sensitive; watch for infection, hypovolaemia and clots.
• HUS: bloody diarrhoea then anaemia, low platelets and AKI — supportive care, no antibiotics.
• Enuresis: look for causes if secondary; alarm first line; desmopressin with fluid restriction.
• 4 Ts (Toilet, Thirsty, Tired, Thinner): same-day finger-prick glucose and same-day referral.
• Type 1 diabetes: basal–bolus or pump, CGM, hybrid closed loop; HbA1c 48 or below; never stop insulin when ill.
• Paediatric DKA: slow rehydration over 48 hours, insulin 0.05–0.1 units/kg/hour started 1–2 hours after fluids, no bolus.
• Cerebral oedema (headache, bradycardia, rising BP) — hypertonic saline or mannitol immediately.
• Hypoglycaemia without diabetes: take a hypo screen during the episode.
• Congenital hypothyroidism is screened at birth — start levothyroxine within 2 weeks.
• CAH: virilised girls; boys present with salt-wasting crisis at 1–3 weeks (low sodium, high potassium, low glucose) — hydrocortisone.
• Emergency hydrocortisone: 25 mg under 1, 50 mg aged 1–5, 100 mg aged 6 and over.
• Ambiguous genitalia: urgent assessment; don't guess the sex; check electrolytes.

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Guidelines and Further Reading

• NICE NG224: Urinary tract infection in under 16s — diagnosis and management
• NICE CG54: Urinary tract infection in under 16s (imaging)
• NICE CG111: Bedwetting in under 19s
• NICE NG18: Diabetes (type 1 and type 2) in children and young people
• NICE TA943: Hybrid closed loop systems for managing blood glucose in type 1 diabetes
• BSPED: Guideline for the management of children and young people under 18 with diabetic ketoacidosis
• British Association for Paediatric Nephrology: guidance on nephrotic syndrome
• BSPED: Adrenal insufficiency and CAH guidance (emergency steroid doses)
• BNF for Children — for current doses

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