The diagnostic approach to hematuria - Veterinary Medicine
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The diagnostic approach to hematuria
A common finding in dogs and cats, hematuria causes a swarm of differential diagnoses to come to mind. This internist provides a series of algorithms to help you zero in on the cause.


VETERINARY MEDICINE


STEP 4: PINPOINT THE CAUSE BASED ON DIAGNOSTIC TEST RESULTS


Table 1: Causes of Hematuria Based on Algorithm Findings and Localization of Urogenital Source
Table 1 summarizes possible causes of hematuria based on potential outcomes of the diagnostic algorithms for suspected urogenital sources.

Exercise-induced hematuria may represent a rare subcategory of trauma that is diagnosed by excluding other causes of hematuria and noting a history of vigorous exercise that occurred within minutes to a few days before blood became apparent in the urine.8,9 Exercise-induced hematuria, as described in people, is transient and is thought to be primarily related to bladder mucosal damage that occurs as a result of repetitive or vigorous movement of the bladder during exercise. In some cases, the source of exercise-induced hematuria may be nontraumatic and occur as a result of increased glomerular excretion of RBCs into the urine.10,11

Although uncommon, leakage of RBCs through the glomerulus can occur because of chronic congestive mechanisms resulting from disorders such as heart failure8,12 or as a consequence of ischemic and congestive mechanisms associated with exercise-induced hematuria.11

Renal hematuria can fall in an idiopathic category. Primary (idiopathic) renal hematuria is thought to result from benign vascular abnormalities that are not readily recognizable through typical diagnostic procedures.13-15

SUMMARY

Handling patients with hematuria begins with confirming RBCs in the urine since a variety of pigmented substances can discolor the urine. Hematuria can be confused with hemoglobinuria, myoglobinuria, bilirubinuria, and pseudohematuria. Once RBCs have been confirmed, historical and physical examination findings can often localize the source of hematuria to the upper urinary tract, lower urinary tract, or genital tract. Coagulopathies must be differentiated from disease of the urogenital tract as the source of urine RBCs. After localizing the source of hematuria, you can follow a series of algorithmic steps delineating a logical diagnostic plan to identify categories of disorders that can lead to a specific cause of hematuria.

Mary Bowles, DVM, DACVIM
Department of Veterinary Clinical Sciences
Center for Veterinary Health Sciences
Oklahoma State University
Stillwater, OK 74078

REFERENCES

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10. Gambrell RC, Blount BW. Exercise–induced hematuria. Am Fam Physician 1996;53(3):905–911.

11. Arbarbanel J, Benet AE, Lask D, et al. Sports hematuria. J Urol 1990;143(5):887-890.

12. Lorenz MD. Discolored urine. In: Lorenz MD, Cornelius LM, eds. Small animal medical diagnosis. Philadelphia, Pa: JB Lippincott Co, 1987;331-342.

13. DiBartola SP. Renal disease: clinical approach and laboratory evaluation. In: Ettinger SJ, Feldman EC, eds. Textbook of veterinary internal medicine. 6th ed. St. Louis, Mo: Elsevier, 2005;1716-1730.

14. Forrester SD. Diagnostic approach to hematuria in dogs and cats. Vet Clin North Am Small Anim Pract 2004;34(4):849-866.

15. Berent AC. Endourology and interventional radiology of the urinary tract, in Proceedings. Am Coll Vet Intern Med Forum 2007.


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