Pediatric Nephrology and Urology
What to master
Know renal maturation-immature GFR and concentrating ability in neonates-and how this affects fluid and drug management. Understand glomerular disease patterns: nephrotic syndrome (proteinuria, hypoalbuminemia, edema, hyperlipidemia; minimal change most common) versus nephritic syndrome (hematuria, hypertension, oliguria; post-streptococcal most common). Master urinary tract infection diagnosis and the importance of excluding vesicoureteral reflux and obstruction. Know hematuria workup (glomerular vs lower tract) and hypertension causes by age.
Concepts that recur
Hyponatremia in a child with renal disease may reflect dilution or sodium loss; assess volume status first. Hyperkalemia is a medical emergency-know ECG changes and treatment sequence (calcium, insulin/glucose, bicarbonate, salbutamol, then removal). Acute kidney injury is staged by creatinine and urine output; distinguish prerenal (responds to fluid) from intrinsic (does not). Enuresis is common and usually functional; nocturnal enuresis without daytime symptoms rarely needs imaging. Cryptorchidism requires referral if not descended by 6 months. Posterior urethral valves present with poor stream, palpable bladder, and hydronephrosis.
Traps
Examiners test nephrotic versus nephritic with overlapping features-look for hypertension and hematuria (nephritic) versus massive proteinuria and edema (nephrotic). Another trap is treating UTI without considering age: infants may present with nonspecific fever and need urine culture before antibiotics. Beware steroid response in minimal change disease-most respond, but nonresponse suggests another histology.
Rule of thumb
Edema + massive proteinuria + low albumin = nephrotic; hematuria + hypertension + oliguria = nephritic. In any febrile infant without a source, obtain a urine sample.