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Evaluation of hematuria
Careful history taking is central in the evaluation of hematuria and provides diagnostic clues. For instance, the occurrence of concomitant flank pain with radiation to the ipsilateral testicle or labia suggests underlying urinary tract stones; burning on urination or dysuria may point to possible UTI; a recent bout of upper respiratory tract infection may suggest either postinfectious glomerulonephritis or IgA nephropathy. A family history of hematuria is also helpful, because certain diseases tend to run in families, such as polycystic kidney disease or sickle cell nephropathy. Likewise, thin basement membrane nephropathy (TBMN; also known as benign familial hematuria) occurs in families and is notable for having a benign course. Exercise-induced hematuria is a benign condition seen in adolescents who exercise vigorously (e.g., long-distance runners).
In elderly individuals (those older than age 50) the finding of gross or microscopic (even transient) hematuria should trigger an evaluation to rule out malignancy involving the genitourinary tract. The incidence of bladder cancer and other malignancies involving the kidneys and the ureters is significantly elevated, particularly in those with a history of smoking or analgesic use. Increased urgency and frequency with hematuria is suggestive of urinary tract obstruction secondary to either prostatic disease or cervical cancer.
Asymptomatic hyperuricosuria or hypercalciuria (spot urine calcium to urine creatinine ratio >0.20 mg/mg) can also cause hematuria. These are more common causes of microscopic hematuria in children, although they have also been reported in adults.
An important aspect of the evaluation of patients with hematuria is to differentiate glomerular from nonglomerular bleeding. For those with glomerular bleeding, especially in the presence of other features such as proteinuria or progressive decline in kidney function, a percutaneous kidney biopsy may be necessary.
Glomerular Versus Nonglomerular Bleeding
| GLOMERULAR | NONGLOMERULAR |
|---|---|
| Associated with: Proteinuria >500 mg/day Red blood cell (RBC) casts Dysmorphic RBCs Usually seen in acute glomerulonephritis, thin basement membrane nephropathy (TBMN) | Associated with: Proteinuria <500 mg/day Absent RBC casts Absent dysmorphic RBCs Renal Causes: Tubulointerstitial nephritis Polycystic kidney disease Sickle cell disease or trait Renovascular disease (atheroembolic renal disease, renal vein thrombosis, arteriovenous malformations, nutcracker syndrome) Urologic Causes: Tumors or malignancies Stones Infections (urethritis, prostatitis, cystitis, pyelonephritis) Medications: Chemotherapeutic agents (cyclophosphamide, ifosfamide, mitotane) Anticoagulants |
