The significance of proteinuria should always be evaluated in light of the method of collection, urine specific gravity, and measurement technique. The amount of protein assessed by qualitative methods such as colormetric dip sticks becomes more significant as the urine decreases in urine specific gravity. Protein can be measured by semiquantitative methods including colormetric dip sticks, turbidometric methods or by quantitative methods. The semiquatitative methods of protein measurement may result in erroneous results including both false positive and false negative results.
Quantitative methods are less likely to return false positive or false negative results.
These other proteins can be detected by the dipstick but only when presnt in large quantities. The dipstick may register a false negative if the urine is very dilute urine. The range of pH of dog and cat urine in both health and disease rarely results in a pH high enough to result in a false postive reading. Turbidimetric methods for protein measurement Turbidimetric tests are based upon the precipitation of protein by the addition of sulfosalicylic acid resulting in relative degress of turbidity of the urine sample. False positive readings may occur if the urine contains radiographic contrast agents or large amounts of antibiotics including penicillins, cephalosporins or sulfonamides.