Residency · Residency · Medicine Pediatrics
Hematuria Evaluation: Red Urine Across Ages
Introduction
Hematuria -- blood in the urine -- is a common finding in both pediatric and adult medicine, with a broad differential diagnosis ranging from benign causes to life-threatening malignancy. The evaluation must be age-appropriate, as etiologies differ substantially between children and adults. Med-peds physicians must distinguish true hematuria from non-hematuria causes of red urine, differentiate glomerular from non-glomerular bleeding, and apply evidence-based evaluation strategies across the lifespan.
Definitions and Classification
Gross (macroscopic) hematuria: Visible red, brown, or tea-colored urine. Microscopic hematuria: >=3 RBCs per high-power field on microscopic examination of centrifuged urine sediment on 2-3 separate specimens. Transient hematuria: Single episode; often benign (exercise, fever, dehydration) Persistent hematuria: Present on >=2 of 3 specimens over 2-4 weeks; warrants further evaluation.
Non-Hematuria Causes of Red Urine
Hemoglobinuria: Dipstick positive for blood, but no RBCs on microscopy (hemolysis) Myoglobinuria: Rhabdomyolysis; dipstick positive, no RBCs, elevated CK. Medications: Rifampin, phenazopyridine, nitrofurantoin, doxorubicin. Foods: Beets (beeturia), blackberries, rhubarb. Metabolic: Porphyria, alkaptonuria. Menses contamination: Important to exclude in menstruating females.
Glomerular vs. Non-Glomerular Hematuria
| Feature | Glomerular | Non-Glomerular |
|---|---|---|
| Urine color | Brown, tea, or cola-colored | Bright red or pink |
| Clots | Absent | May be present |
| RBC morphology | Dysmorphic, acanthocytes | Isomorphic (normal) |
| Proteinuria | Often present | Usually absent |
| RBC casts | Present (pathognomonic) | Absent |
Pediatric Differential Diagnosis
Glomerular Causes
Post-infectious glomerulonephritis (PIGN): Most common glomerulonephritis in children; follows group A strep infection by 1-3 weeks; low C3, elevated ASO/anti-DNase B; self-limited. IgA nephropathy: Episodic gross hematuria during or shortly after URI ("synpharyngitic hematuria"); most common glomerulonephritis worldwide. Alport syndrome: X-linked or autosomal; progressive hematuria, sensorineural hearing loss, and lenticular changes; positive family history. Henoch-Schonlein purpura (IgA vasculitis) nephritis: Hematuria and proteinuria with palpable purpura, arthritis, abdominal pain. Lupus nephritis: Consider in adolescent females with multi-system involvement.
Non-Glomerular Causes
Urinary tract infection: Most common cause of hematuria in children; pyuria and bacteriuria present. Hypercalciuria: Idiopathic; elevated urine calcium-to-creatinine ratio; may cause hematuria without stones. Nephrolithiasis: Less common in children than adults; evaluate for metabolic causes. Trauma: Renal contusion or laceration; consider non-accidental trauma in young children. Congenital anomalies: UPJ obstruction, polycystic kidney disease, posterior urethral valves (males) Exercise-induced hematuria: Benign; resolves within 48-72 hours of rest. Wilms tumor: Rare but important; typically presents in children aged 1-5 with abdominal mass.
Adult Differential Diagnosis
Glomerular Causes
IgA nephropathy: Most common glomerulonephritis; episodic hematuria with URI. Membranoproliferative glomerulonephritis: Associated with hepatitis C, cryoglobulinemia. Anti-GBM disease (Goodpasture syndrome): Pulmonary hemorrhage and rapidly progressive glomerulonephritis. ANCA-associated vasculitis: Granulomatosis with polyangiitis, microscopic polyangiitis.
Non-Glomerular Causes
Urinary tract malignancy: Bladder cancer is the most important cause to exclude in adults over 35 with hematuria; risk factors include smoking, occupational exposures. Nephrolithiasis: Common in adults aged 20-50; flank pain, colicky nature. UTI/pyelonephritis: Dysuria, frequency, and pyuria. BPH: Prostatic enlargement causing hematuria in older men. Renal cell carcinoma: Classic triad of hematuria, flank pain, and palpable mass (present in <10%) Anticoagulation: Does not cause hematuria de novo; unmasks underlying pathology that requires evaluation. Polycystic kidney disease: Autosomal dominant; cyst rupture or infection.
Evaluation Approach
Pediatric Evaluation
Urinalysis with microscopy: Confirm true hematuria; assess for casts, dysmorphic RBCs, proteinuria. Urine culture: Exclude infection. Serum creatinine, BUN, albumin: Assess renal function. Complement levels (C3, C4): Low C3 in PIGN, MPGN, lupus nephritis. Urine calcium-to-creatinine ratio: Screen for hypercalciuria (>0.2 in children >2 years) Renal ultrasound: Evaluate anatomy, stones, masses, cystic disease. Referral to pediatric nephrology: For persistent hematuria with proteinuria, dysmorphic RBCs, or abnormal renal function.
Adult Evaluation
Urinalysis with microscopy: Characterize hematuria type. Urine cytology: For patients at risk for urothelial carcinoma. CT urogram: Preferred imaging for adults with unexplained hematuria; evaluates upper tracts. Cystoscopy: Recommended for all adults >=35 years with unexplained microscopic or gross hematuria (AUA guidelines) Renal function tests: Creatinine, eGFR. Nephrology referral: For glomerular hematuria (dysmorphic RBCs, RBC casts, proteinuria) Urology referral: For non-glomerular hematuria in adults, especially >=35 years, for cystoscopy and upper tract imaging.
Special Considerations
Sickle cell trait and disease: Common cause of hematuria in Black patients; papillary necrosis and renal medullary carcinoma are serious complications. Thin basement membrane nephropathy: Benign familial hematuria with excellent prognosis; distinguished from early Alport syndrome by genetic testing. Nutcracker syndrome: Compression of left renal vein between aorta and SMA; causes left-sided hematuria, more common in thin individuals.
Clinical Pearls
Always confirm hematuria with microscopy; dipstick-positive results may reflect hemoglobinuria or myoglobinuria rather than true hematuria. RBC casts are pathognomonic for glomerulonephritis; dysmorphic RBCs suggest glomerular origin. In adults over 35, unexplained hematuria requires cystoscopy and upper tract imaging to exclude malignancy regardless of anticoagulation status. Post-infectious glomerulonephritis is the most common glomerulonephritis in children and typically resolves spontaneously with normalization of C3 within 6-8 weeks. Hematuria in a patient on anticoagulation still requires full evaluation; anticoagulation unmasks but does not cause urinary tract pathology.
References
- Ingelfinger JR, Davis AE, Bhatt K. Evaluation of hematuria in children. N Engl J Med. 2021;385(27):2559-2565.
- Barocas DA, Boorjian SA, Alvarez RD, et al. Microhematuria: AUA/SUFU guideline. J Urol. 2020;204(4):778-786.
- Yuste C, Gutierrez E, Sevillano AM, et al. Pathogenesis of glomerular haematuria. World J Nephrol. 2015;4(2):185-195.
- Massengill SF. Hematuria. Pediatr Rev. 2008;29(10):342-348.