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Thread: Hematuria

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    PharmD Year 1 TomHsiung's Avatar
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    Jan 2013
    Chengdu, Sichuan, China

    Default Hematuria

    Red urine is not always caused by hematuria. A variety of medications, food dyes, and metabolites can cause heme-negative red urine, or pigmenturia. Furthermore, not all dipstick tests positive for blood are due to hematuria. In addition to detecting heme in intact red blood cells (RBCs), urine dipsticks detect free hemoglobin and myoglobin, hence leading to false-positive tests for hematuria.


    Whenever the urine dipstick is positive for blood, and the microscopic exam of the urine does not show RBCs, myoglobinuria and hemoglobinuria should be considered.

    True macroscopic (visible) hematuria is always pathologic. Microscopic (nonvisible) hematuria may be transient, spurious, or persistent. Transient causes of microscopic hematuria include urinary tract infections (UTIs) (which sometimes also cause macroscopic hematuria) and strenuous exercise; hematuria due to these causes would be expected to resolve on repeat testing after 48 hours of treatment or after discontinuing exercise for 72 hours. Spurious causes include urinary contamination from menstruation and sexual intercourse in women.

    All patients with hematuria should have a urine culture performed, regardless of the likelihood of infection.

    The differential diagnosis of hematuria is often divided into microscopic hematuria or macroscopic hematuria. Microscopic hematuria is present when microscopic inspection of at least 2 properly collected urine specimens show >3 RBCs per high-powered field (hpf). Macroscopic hematuria is red or brown urine, sometimes with blood clots. However, there is considerable overlap in the causes of microscopic and macroscopic hematuria, and it may be more practical to first consider whether the hematuria is glomerular in origin.

    Differential Diagnosis
    • Renal
      • Glomerular
        • IgA nephropathy
        • Alport disease and thin basement membrane nephropathy (TBMN)
        • Other primary and secondary glomerulonephritides
          • Postinfectious or infection-related
          • Systemic lupus erythematosus
          • Goodpasture syndrome
          • Henoch-Schunlein purpura (HSP) and other small or medium vessel vasculitides
          • Hemolytic uremic syndrome (HUS)

      • Nonglomerular
        • Neoplastic
          • Renal cell or transitional cell carcinoma
          • Benign renal mass

        • Tubulointerstitial
          • Nephrolithiasis
          • Polycystic kidney disease or medullary sponge kidney
          • Pyelonephritis
          • Acute interstitial nephritis
          • Papillary necrosis

        • Vascular
          • Arterial embolus or thrombosis
          • Arteriovenous malformation or arteriovenous fistula
          • Renal vein thrombosis
          • Nutcracker syndrome (compression of left renal vein)
          • Malignant hypertension

        • Metabolic (hypercalciuria, hyperuricosuria)

    • Extrarenal
      • Ureter
        • Mass: benign polyp or malignancy
        • Stone
        • Stricture

      • Bladder
        • Transitional cell or squamous cell carcinoma
        • Noninfectious cystitis (radiation or medication [cyclophosphamide])
        • Infectious cystitis
        • Stone

      • Urethra
        • Urethritis
        • Urethral diverticulum
        • Traumatic catheterization
        • Urethral stricture

      • Prostate
        • Benign prostatic hypertrophy (BPH)
        • Prostate cancer
        • Post prostatic procedure
        • Prostatitis

    Pivotal Points
    • Nonvisible or visible
    • Dysmorphic RBCs (acanthocytes)
    • Red cell casts
    • New or acutely worsening hypertension or proteinuria
    • Increased creatinine
    • Visible blood clots


    Last edited by TomHsiung; Mon 10th April '17 at 10:04pm.
    B.S. Pharm, West China School of Pharmacy, Class of 2007, Health System Pharmacist, RPh. Hematology, Infectious Disease.

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