Delimitation of plasma creatinine concentration values for assessment of relative renal function in adult patients.

Plasma creatinine concentrations and glomerular filtration rates (GFR) were determined simultaneously in 200 females and 180 males of various ages (20-79 years) covering all degrees of relative renal function: normal (greater than 75%); moderately impaired (75-52%); considerably impaired (51-28%); and severely impaired (greater than 28%). The percentages express GFR relative to corresponding age--and sex-dependent normal means. This relative parameter evaluates whether--and to what extent--the combined function of the two kidneys is affected by nephro-urological disorders. For practical purposes plasma creatinine was found to be independent of age in all function groups for both sexes. The data were used to delimit plasma creatinine concentrations for the assessment of relative renal function. For females the limits of plasma creatinine (mumol per litre) were: "normal" (less than 115); "moderately elevated" (115-150); "considerably elevated" (151-250); and "profoundly elevated" (greater than 250). The corresponding figures for males were: less than 128; 128-170; 171-270; and greater than 270.