Colorimetric Determination and Distribution of Urinary Creatinine and Creatine

Abstract

Abstract “Apparent” creatinine and “total” creatinine levels in urine can be estimated to within 2 per cent accuracy by means of the Jaffe colorimetric reaction, provided that certain requirements for the colorimetric reaction itself are met, and provided that appropriate conditions for the conversion of creatine to creatinine are used. The amount of noncreatinine Jaffe-positive material appears to be negligible in most urines, but it can be evaluated with paper chromatography and ion-exchange technics. More than 88 per cent of normal subjects excrete 300-900 mg. creatinine per 100 lb. of total body weight per day, with the average at 600 mg. Normal males excrete creatinine at an average rate of 875 mg. Creatine excretion in normal subjects ranges more widely. From 0-800 mg. per 100 pounds of total body weight per day is excreted (as. creatinine), with the average at 275 mg., regardless of sex or age. Certain malabsorption syndromes (cystic fibrosis and celiac disease) include distinct creatinurias.