THE METABOLISM OF CORTISOL-4-C14IN YOUNG AND ELDERLY MEN. I. SECRETION RATE OF CORTISOL AND DAILY EXCRETION OF TETRAHYDROCORTISOL, ALLOTETRAHYDROCORTISOL, TETRAHYDROCORTISONE AND CORTOLONE (20α AND 20β)*
The average 24-hour secretion rate of cortisol, as determined from the excretion of any one of the four major urinary metabolites, THF, ATHF, THE, or cortolone (20[alpha] and 20[beta]), for 8 elderly men was 75 percent of that for 8 young men. When the secretion rates were expressed as mg.per gm.of creatinine per twenty-four hours, the average rates were essentially the same -14 mg versus 15 mg, for both groups of subjects. These findings substantiate those obtained for the mean total 24-hour excretions of THF, ATHF, THE and cortolone, which for 23 elderly men was approximately 70 percent of that for the 23 young men. When these values are expressed as mg-per gm.of creatinine, the mean of 4.9 mg for young men compares with that of 4.7 mg for elderly men. In both age groups there were essentially similar proportions of the two 11-hydroxyl (THF, ATHF) to the two 11-ketone substituted metabolites (THE, cortolone), and of the three 5[beta] (THF: THE, and cortolone) to the one 5[alpha] (ATHF) cortisol metabolite. Aging, by the criteria employed, appears to be differentiated only by the quantity of adrenally secreted cortisol which may be related to the muscle mass of the subject.