Table 1 gives a listing of normal daily urinary protein excretion as a function of age. There are two semiquantitative tests for proteinuria. The most common is the dipstick method. Urinary protein induces color changes of the indicator dye, tetrabromphenol, which is buffered to maintain the pH of the paper at 3.0. The test in unaffected by x- ray contrast material and drugs.
False positives occur with strongly alkaline urine.
In patients with nonalbumin proteinuria, the dipstick may demonstrate no color change. To circumvent missing mild proteinuria, it is recommended that only concentrated urines be tested. The second method is a turbidimetric test using sulfosalicylic acid. False positive reactions may occur with x- ray contrasts media, penicillin, and sulfisoxazole metabolites. This type of proteinuria can occur in association with strenuous exercise, emotional stress, extreme cold, epinephrine administration, abdominal surgery, or congestive heart failure.