Microalbuminuria occurs when the concentration of albumin in the urine is higher than normal but below the limit detectable with conventional urine dipsticks (usually 30 mg/ml or more). Studies have evaluated the prevalence of microalbuminuria in dogs and cats. In dogs, microalbuminuria was found to be as high as 36%; it was more prevalent in older dogs and in certain breeds. When 611 clinically healthy cats were evaluated, more than 13% had microalbuminuria. In a separate study of sick cats, almost 43% had microalbuminuria. The protein found in the urine is preglomerular, glomerular, or postglomerular. Some transient events, such as fever, seizures and hypothermia, may cause proteinuria without pathologic glomerular disease. Postglomerular causes of microalbuminuria or overt albuminuria include diseases of inflammation or hemorrhage of the urogenital tract and failure of the renal tubules to reabsorb and/or degrade filtered albumin, resulting in such disorders as urolithiasis, infectious cystitis, and renal tubular disease. Glomerular microalbuminuria can occur for a variety of reasons in dogs and cats, including heartworm disease, heart disease, neoplasia, and urogenital disease. A point-of-care immunoassay diagnostic test that can identify microalbuminuria in dogs and cats is available. It can be used when animals have a known risk for familial glomerular diseases or when they reach the age that prevalence of microalbuminuria begins to increase (6 years). Positive screening tests should be repeated in about 4 weeks. If results are still positive, causes should be investigated. Early identification may allow for early intervention and may slow the progression of renal failure.
COMMENTARY: Because this test is relativity new, its usefulness is still being evaluated. However, it definitely recognizes proteinuria before other readily available testing methods. This test also allows determination of whether microalbuminuria is increasing, indicating whether disease is progressing, stable, or decreasing.
Microalbuminuria: What does it mean for my patient? Pressler BK, Vaden SL. Wild West Vet Conf, October 2003.