Urine Blood: Multistix

"Blood-stix" represents the reaction observed on the hemoprotein pad of the multireagent urine dipstick. This test is based on detection of the "peroxidase-like" activity inherent in molecules of heme (present in hemoglobin or myoglobin). The reaction is very sensitive and will detect:

Hematuria Hemoglobinuria Myoglobinuria Mechanism - RBCs lyse on contact with the reagent pad, causing a positive reaction (speckled pattern may result if low-grade) Mechanism - free Hb filtered into urine as a result of hemoglobinemia (usually detectable as visibly red plasma). Mechanism - free Mb filtered into urine as a result of myoglobinemia (not visually detectable in plasma). Clinical - Bleeding into urinary space; can occur at any level of the tract). Commonly due to inflammation, trauma, neoplasia, hemostatic disorders. Clinical - Intravascular hemolysis of any cause: immune-mediated, toxic, mechanical, infectious, etc. Clinical - Myocyte injury allowing release of myoglobin which reaches bloodstream and is readily filtered at the glomeruli.

Differentiation of hemoglobinuria vs. myoglobinuria by direct testing of urine alone is generally impractical. Interpretation of a positive hemoprotein result in light of the case context and the results of urine sediment, clinical chemistry and hematology examinations usually allows indirect identification as follows: Hematuria: RBC will be present on urine sediment examination (if hematuria is marked, a red precipitate forms after centrifugation of urine). Hemoglobinuria: There will be no RBC on the urine sediment and the urine supernatant will be red (remember that RBC will lyse in very dilute or alkaline urine). In general, affected animals have a low hematocrit (in rare cases of intravascular hemolysis, the hematocrit may be normal due to concurrent dehydration). Myoglobinuria: There will be RBC on the urine sediment and the urine will have a red supernatant. The affected animal will have a very high CK and (maybe) high AST, reflecting muscle injury. In rare instances, myoglobinuria and hemoglobinuria can pre-exist in a single patient, e.g. a horse with red maple leaf poisoning (an oxidant-induced hemolytic anemia) with concurrent rhabdomyolysis. The distinction between hemoglobin and myoglobin as the cause for the red urine color is academic at this point.