The quality assurance of urinary enzyme measurements is difficult because of lack of suitable control material. The few control urines commercially available are mostly prepared for special purposes; their enzymatic activities are either not declared or the preparations are enzymatically inactive. The usual commercial liquid or lyophilized material based on human or animal serum, although occasionally used , cannot replace a special control material for urinary enzymes because it does not contain some of the enzymes of interest and because the activities of a number of enzymes present in the control sera differ substantially from those of urine. Furthermore, the enzymes of control sera show kinetic characteristics which differ from those of urinary enzymes and would not meet the essential “similar behaviour” requirements of control materials .
KeywordsQuality Assurance Human Urine Control Material Control Seron Gamma Glutamyltranspeptidase