๐Ÿงช Chapter 19: Proteinuria

Nelson's Pediatric Symptom-Based Diagnosis | Transient ยท Orthostatic ยท Persistent ยท Nephrotic Syndrome ยท Red Flags

๐Ÿ” Proteinuria in Children: Key Concepts

๐Ÿ“Š Detection & Quantification
Dipstick: detects albumin only (false + if alkaline/concentrated). Spot protein:creatinine ratio (>0.2 mg/mg >2yrs). 24-hour >100 mg/mยฒ abnormal; >40 mg/mยฒ/hr nephrotic range.
๐Ÿ”„ Benign Proteinuria
Transient: fever, exercise, seizures, stress. Orthostatic: protein only when upright (absent in first morning void). No treatment needed.
โš ๏ธ Pathologic Proteinuria
Persistent non-orthostatic โ†’ glomerular disease (RBC casts, hypertension) or tubular (low MW proteins, Fanconi). Needs nephrology referral.
๐Ÿ’ง Nephrotic Syndrome
Proteinuria (>40 mg/mยฒ/hr) + hypoalbuminemia + edema + hyperlipidemia. Minimal change disease (80%): prednisone responsive, excellent prognosis.
๐Ÿงฌ Other Glomerulopathies
FSGS (steroid-resistant, poor prognosis), membranous nephropathy, congenital nephrotic syndrome (nephrin mutations). Genetic forms associated with podocyte genes.
๐Ÿšฉ Red Flags
Edema + hypertension + azotemia โ†’ glomerulonephritis. Age <1yr or >10yrs + hematuria โ†’ non-minimal change. Fever + abdominal pain in nephrotic โ†’ peritonitis.

๐Ÿ’ก Key Takeaway: Asymptomatic proteinuria is often benign (transient/orthostatic). Persistent proteinuria requires quantification, first morning void, and evaluation for edema/hypertension. Nephrotic syndrome in children is usually minimal change disease, highly steroid-responsive. Refer to nephrology for persistent non-orthostatic proteinuria or nephrotic-range proteinuria.

๐Ÿฉบ Clinical Approach to Proteinuria: Step-by-Step Algorithm

๐Ÿ”น Step 1: Confirm true proteinuria
โ€ข Repeat dipstick on first morning void (avoid false + from concentrated urine, alkaline pH, contrast).
โ€ข Spot urine protein:creatinine ratio >0.2 mg/mg (>2yrs) confirms abnormal protein excretion.
๐Ÿ”น Step 2: Differentiate transient vs orthostatic vs persistent
โ€ข Transient: associated with fever, exercise, seizures โ†’ resolves when trigger removed.
โ€ข Orthostatic: protein present in daytime sample but absent in first morning void (split day/night collection gold standard).
โ€ข Persistent: protein in first morning void on โ‰ฅ2 occasions โ†’ pathologic until proven otherwise.
๐Ÿ”น Step 3: Evaluate for nephrotic syndrome & glomerular disease
โ€ข Check serum albumin, cholesterol, BUN, creatinine, C3/C4.
โ€ข Edema, periorbital puffiness, ascites โ†’ suspect nephrotic syndrome.
โ€ข Hypertension + hematuria + red cell casts โ†’ glomerulonephritis (post-streptococcal, IgA, lupus).
๐Ÿ”น Step 4: When to refer to nephrologist
โ€ข Persistent non-orthostatic proteinuria.
โ€ข Nephrotic-range proteinuria (spot P:Cr >2.0 mg/mg) even without edema.
โ€ข Family history of kidney failure, hematuria, systemic symptoms (rash, arthritis).
โ€ข Elevated creatinine or hypertension.
๐Ÿ”น Step 5: Management pearls
โ€ข Minimal change disease: prednisone 60 mg/mยฒ/day for 4-6 weeks, then alternate day for 6 weeks. Relapses common.
โ€ข ACE inhibitors/ARBs reduce proteinuria and preserve renal function in chronic proteinuric nephropathies.
โ€ข Spontaneous bacterial peritonitis: any fever/abdominal pain in nephrotic syndrome โ†’ paracentesis + empiric antibiotics (cefotaxime).