The Interference of Penicillin in the Determination of Albumin in Urine *

Observations made on animals subjected to parenteral administration of penicillin, at relatively high levels, disclosed a pseudopositive albumin reaction. While it is not known if similar reactions have been noted after clinical treatment, there is at least a possibility that in cases where unusually high penicillin dosages are administered similar phenomena may occur. Most tests for albumin in urine are based upon the visual demonstration of the precipitation of the protein from the urine by use of a strong acid reagent. The question as to which is the best test to use has been the subject of much debate. The method of choice perhaps frequently depends upon the ease with which it may be performed and the sensitivity desired; however, for general laboratory studies we have preferred to use Robert's qualitative albumin test.3 Exton's sulfosalicylic acid method,' Purdy's acetic acid test,4 and Heller's nitric acid test,4 one of the oldest methods commonly used, were also investigated.