Veterinary Medicine - December 2007 - (Page 784)

2007 Highlights O Central Practical advice from the presentations Investigating proteinuric kidney disease When does protein in a urine sample necessitate further patient evaluation and treatment? David J. Polzin, DVM, PhD, DACVIM (small animal internal medicine) D o you sometimes detect protein in a sick patient’s urine or even on routine testing in a seemingly healthy patient and you’re not sure what to make of it? If red blood cells or inflammatory cells are not present, the proteinuria could be important. But first, retest the patient’s urine a week or two later to see if the results are repeatable. If not, the previous proteinuria may have been caused by a one-time event, such as stress, fever, or vigorous exercise. Also consider that one cause of false positive urine protein results on a dipstick test is alkaline urine. And a false positive result may occur with a turbidometric test performed by a diagnostic laboratory if a patient has recently received penicillins, cepha- ASSESSING URINE PROTEIN/CREATININE RATIOS Urine protein/creatinine ratios 0.5 in dogs and > 0.4 in cats necessitate a more thorough work-up. Ratios > 3 may indicate glomerular disease. With lower abnormal ratios, also consider nonglomerular pathology, such as hypertension, hyperadrenocorticism, or renal tubule defects. Nonazotemic patients with ratios > 2, azotemic dogs with ratios > 0.5, High levels of proteinuria can be directly nephrotoxic. losporins, sulfonamides, or radiographic contrast agents. If the second sample shows proteinuria, perform a urine protein/creatinine ratio to determine the extent of protein loss in the urine. and azotemic cats with ratios > 0.4 warrant treatment. In patients with substantial proteinuria, hypoalbuminemia may occur. and hyperadrenocorticism. Urine bacterial culture and sensitivity testing are also warranted, especially in patients with dilute urine concentrations. Test cats for feline leukemia virus and feline immunodeficiency virus infections if their status is unknown. Since hypertension can be closely associated with proteinuria and many of the diseases that cause it, be sure to obtain serial blood pressure measurements. Thoracic and abdominal radiographic or ultrasonographic examinations may also yield important information. Obtaining kidney biopsy samples may be helpful in some patients. And certain breeds may be predisposed to familial kidney diseases, so it’s important to research this possibility as well. FURTHER EVALUATION If a more thorough work-up is indicated, perform a serum chemistry profile to evaluate albumin, blood urea nitrogen, creatinine, and cholesterol concentrations and liver enzyme activities and a complete blood count to detect any abnormalities consistent with an infectious or inflammatory process. Additional blood testing may be needed to rule out heartworm disease, tick-borne illnesses, THERAPEUTIC MEASURES Over time, marked proteinuria can lead to severe hypoalbuminemia and edema, hypercoagulopathy, and progressive kidney disease. High levels of proteinuria can be directly nephrotoxic—so it’s important to treat these patients. Switching to a renal diet may reduce albumin loss in the urine but should not reduce the serum albumin concentration. So be ©iStockphoto.com/christine balderas David J. Polzin, DVM, PhD, DACVIM (small animal internal medicine) Department of Veterinary Clinical Sciences College of Veterinary Medicine The University of Minnesota St. Paul, MN 55108 784 December 2007 VETERINARY MEDICINE

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Veterinary Medicine - December 2007 Contents Letters Editors' Guest Thanking Our Valued Reviewers The Veterinary Medicine Interview: Dr. Joseph Harari Clinical Exposures Idea Exchange Answers to Three Commonly Asked Questions About Lyme Disease Practical Ideas for Managing Common Internal Medicine Problems A Tip for Interpreting Leptospira Species Titers Investigating Proteinuric Kidney Disease Counseling New Puppy Owners: Normal Play vs. Aggressive Tendencies 11 Guidelines for Conservatively Treating Chronic Kidney Disease CE Form Product Preview Advertiser Index Marketplace/Classifieds Mind Over Miller Merial Insert

Veterinary Medicine - December 2007

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