[Clinical studies on urinary tissue polypeptide antigen (TPA): problems and improvement in determination].

The reliability of measurement of urinary TPA using a Prolifigen TPA kit (Sangtec, Sweden) was investigated, and an improved method for stabilizing TPA was tested. Samples were filtrated with a cellulose nitrate membrane filter to remove impurities as a possible cause of a high false positive rate which has been a problem in urinary TPA measurement. Serum TPA and Tween 40-treated urinary TPA was not adsorbed by the filter, whereas TPA in the non-treated urine showed a marked affinity to the filter. This shows the instability of TPA in the original urine, and the impropriety of filtration as a measure of purification of urine samples. The dilution test of urine and the standard TPA, and the recovery test of the standard TPA added to 6 different urine samples showed reasonable results only when the samples were treated with Tween 40; otherwise the values were lower than expected. Thirty-four spot urine samples were tested to examine the change in TPA value during the storage for 24 hours. TPA values decreased when urine was stored at room temperature, but this change was prevented by treatment of urine with Tween 40.