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January 8, 1973

Serum Creatinine and Drug Half-Lives

Author Affiliations

Gentofte Hospital Copenhagen, Denmark

JAMA. 1973;223(2):193. doi:10.1001/jama.1973.03220020059025

To the Editor.—  In your journal, the relationship between serum creatinine and drug half-life has recently been discussed (209:539, 1969; 219:1037, 1972; 221:918, 1972). From the literature, Perrier and Gibaldi have calculated endogenous creatinine production rates varying from 1.17 to 0.8 mg/min. None of these studies mention weight, sex, and age-dependent changes in creatinine production.We have studied the excretion of creatinine in the urine on 479 patients in different age groups.1,2 In men as well as in women, mean values of urinary creatinine per kilogram body weight per 24 hours were found to decrease with age, in men from 23.8 plus or minus 2.5 mg standard deviation in the group aged 20 to 30 years to 9.4 plus or minus 3.2 mg in the group aged 80 to 90 years, and in women from 19.7 plus or minus 3.9 to 8.4 plus or minus 1.4 mg in the same