Nelson's Pediatric Symptom-Based Diagnosis | Gross vs Microscopic · Glomerular vs Non-glomerular · Postinfectious GN · IgA · Alport · Hypercalciuria
🔍 Hematuria in Children: Essential Concepts
🩸 Definitions Gross hematuria: visible blood. Microscopic: ≥5 RBCs/HPF. Up to 40% gross & 80% persistent microscopic have no identifiable cause. AAP does not recommend routine screening.
🧪 Glomerular vs Non-glomerular Glomerular: tea/cola-colored urine, RBC casts, dysmorphic RBCs, proteinuria (>2+). Non-glomerular: bright red, clots, normal RBC morphology, no casts.
🦠 Common Causes UTI (most common identifiable cause), postinfectious GN (strep), IgA nephropathy (painless gross hematuria with URI), hypercalciuria, trauma, sickle cell trait.
⚕️ Evaluation Urinalysis with microscopy, urine culture, renal function, C3/C4 (low C3 in postinfectious GN, normalizes 6-12w). Ultrasound for non-glomerular or recurrent gross hematuria.
🚩 Red Flags Hypertension, edema, oliguria → acute GN. Supraclavicular nodes? No. Flank pain + clots → stone or papillary necrosis. Family history renal failure → Alport.
💡 Key Takeaway: Hematuria in children is rarely a malignancy. RBC casts or dysmorphic RBCs = glomerular source → check C3, ASO, ANA. Bright red blood with clots = lower tract → ultrasound. Most isolated microscopic hematuria without proteinuria or hypertension is benign.
🩺 Clinical Approach to Hematuria: Step-by-Step Algorithm
🔹 Step 1: Confirm true hematuria
• Dipstick positive for blood, confirm with microscopy. If dipstick positive but no RBCs → consider hemoglobinuria (hemolysis) or myoglobinuria (rhabdomyolysis).
• Pink diaper in newborn: often urate crystals (dipstick negative for blood). No further workup.
🔹 Step 2: Distinguish glomerular vs non-glomerular source
• Glomerular: tea/cola/brown urine, RBC casts, dysmorphic RBCs (phase contrast), proteinuria >2+.
• Non-glomerular: bright red or pink, clots, isomorphic RBCs, no proteinuria (except heavy bleeding).
• Clots → almost always lower tract (bladder/urethra) unless clot originates from ureter.
🔹 Step 3: Targeted evaluation based on presentation
• Gross hematuria + dysuria/fever → urine culture (UTI most common identifiable cause).
• Gross hematuria + recent URI/pharyngitis (1-4 weeks prior) → check C3, ASO for poststreptococcal GN.
• Gross hematuria concurrent with URI symptoms → IgA nephropathy.
• Painless gross hematuria + family history → consider Alport or thin basement membrane.
• Microscopic hematuria + hypertension/edema → acute nephritis workup.
🔹 Step 4: Imaging and labs
• Non-glomerular gross hematuria → renal/bladder ultrasound (stones, tumors, hydronephrosis, vascular malformations).
• Hypercalciuria: spot urine Ca:Cr >0.22 (older child), 24h Ca >4 mg/kg/day.
• Sickle cell trait/disease → can cause papillary necrosis; consider in African ancestry.
• Family members urinalysis → helpful for hereditary nephritis.
🔹 Step 5: When to refer to nephrology
• Persistent glomerular hematuria with proteinuria or hypertension.
• Recurrent gross hematuria with unknown cause.
• Family history of renal failure (possible Alport).
• Elevated creatinine or declining renal function.
• Consider renal biopsy for IgA nephropathy, crescentic GN, or unexplained persistent glomerular hematuria.