Long-term stability of albumin, protein HC, immunoglobulin G, kappa- and lambda-chain-immunoreactivity, orosomucoid and alpha(1)-antitrypsin in urine stored at -20 degrees C

The stability of albumin, protein HC, immunoglobulin G, kappa- and lambda-chain immunoreactivity, orosomucoid and alpha(1)-antitrypsin in urine stored at -20 degrees C for up to 24 months was investigated. Significant decreases of the median concentration values for protein HC, IgG and alpha(1)-antitrypsin were observed for native urine. Addition to urine of a preservative solution containing benzamidinium chloride, EDTA, tris(hydroxymethyl)-aminomethane and azide prevented the decreases of the concentration values for protein HC and IgG but not for alpha(1)-antitrypsin. The median concentration values for albumin, orosomucoid and kappa- and lambda-chain immunoreactivity did not change significantly upon storage of native urine, nor for urine with the preservative solution.