STABILITY OF ALBUMIN, PROTEIN HC, IMMUNOGLOBULIN-G, KAPPA-CHAIN AND LAMBDA-CHAIN IMMUNOREACTIVITY, OROSOMUCOID AND ALPHA-1-ANTITRYPSIN IN URINE STORED AT VARIOUS CONDITIONS

Urine samples from 10 randomly selected patients with advanced renal d isease were each divided into six aliquots and a preservative solution containing benzamidinium chloride, EDTA, tris(hydroxymethyl)-aminomet hane and azide was then added to three of the aliquots. Aliquots with and without additive were then stored at room temperature for up to 7 days, at 4 degrees C for up to 30 days and at -20 degrees C for up to 6 months. The concentrations of albumin, protein HC, IgG, orosomucoid and alpha 1-antitrypsin as well as the kappa- and lambda-chain immunor eactivities in the samples were determined by automated immunoturbidim etry or by single radial immunodiffusion after 1, 3, 7, 14, 30, 90 and 180 days of storage. All investigated proteins, except alpha 1-antitr ypsin in native urine, were stable for 7 days in the samples stored at room temperature both in the presence and absence of additives. All i nvestigated proteins, except alpha 1-antitrypsin in native urine, were stable for 30 days in the samples stored at 4 degrees C both in the p resence and absence of additives. A more complex pattern was observed for the stability of the proteins in the frozen samples. The IgG level decreased rapidly in several samples stored without additives but not in samples stored with additives. The alpha 1-antitrypsin concentrati on decreased rapidly to about 50% of the initial value in several samp les stored both with and without additives. The rate of the decrease f or both the IgG and the alpha 1-antitrypsin level varied between sampl es and the main decrease for several samples was seemingly caused by t he freezing and/or thawing per se and not by the storage period in bet ween.