A 31-year-old woman is sent to you because, during a routine physical examination for obtaining health care insurance, she was found to have asymptomatic hematuria with 25-30 erythrocytes/hpf in her urine. Her serum creatinine level is 0.9 mg/dl, and her BUN is 12 mg/dl. On questioning, the patient claims to have had a sore throat within the last month. Past history is unremarkable; she is on no medications. Physical examination is entirely normal, with no hypertension or edema. Urinalysis dipstick shows 4+ hematuria, without protein.

1. What is the differential diagnosis of this patient's hematuria?

Hematuria without proteinuria, renal failure, or hypertension in a young woman--COMMON CAUSES:

• Urologic: cystitis/urethritis, trauma, renal/ureteral stones
• Hypercalcuria/hyperuricuosuria (positive family history of stones; responds to hydrochlorothiazide or allopurinol)
• Glomerular disease:
  1. IgA nephropathy (usually presents as micro- or gross hematuria without nephrotic or nephritic symptoms--onset may be 24-48 hours post viral illness.
  2. Alport's Syndrome--ask patient about family history of deafness or ESRD in male sibs at a young age
• Other: Sickle cell nephropathy, polycystic kidney disease

2. How might microscopic examination of the urine help you diagnose the patient?

• dysmorphic RBC's and RBC casts (c/w glomerulonephritis)
• WBC's/bacteria (c/w infection)
• crystals (c/w stones)
• if no RBC seen despite positive heme dipstick, consider myoglobinuria/hemoglobinuria

3. What test(s) would you do now?

Diagnostic tests (in order of invasiveness) for microscopic hematuria without signs of glomerular disease:

• Repeat UA: hematuria should be present in 2 of 3 specimens for significance
• Urine culture
• 24 hour urine for calcium and uric acid--elevated values warrants trial of HCTZ or allopurinol to see if hematuria clears
• IVP (excretory urogram) OR ultrasound + spiral CT to look for stones
• Cystoscopy? low yield in young people, unless they have bladder symptoms, gross hematuria, or heavy cigarette hx (with increased risk of cancer).
• Renal biopsy? Usually not indicated without proteinuria or elevated SCr

4. How would your differential diagnosis and lab workup differ if the patient were a 70-year-old man?

• Prostatitis is now a likely Dx; likelihood of bladder or renal neoplasm increases.
• Consider early urologic referral for cystoscopy, urine cytology x3 (but only 50% sensitive for cancer), CT for renal neoplasm if other studies negative.