Simplified determinations of the "true" creatinine concentration in serum and urine.

The procedures using Fuller's earth for the specific determination of creatinine were further simplified without loss of reliability. Four routine purposes, deproteinization can be omitted if lipemic sera are excluded. the modification with deproteinization is recommended as a candiate for a selected method. Good correlation with an enzymatic procedure and the lack of relevant interference indicate a high analytical specificity. The Fuller's earth procedure is cheaper and more precise than the enzymatic method and slightly faster than the fading fraction method. Urine samples should also be treated with Fuller's earth before they are subjected to the Jaffé reaction.