THE DAILY CORTISOL PRODUCTION REINVESTIGATED IN HEALTHY-MEN - THE SERUM AND URINARY CORTISOL PRODUCTION-RATES ARE NOT SIGNIFICANTLY DIFFERENT

We have measured the urinary cortisol production rate (uCPR) simultane ously with the serum cortisol production rate (sCPR) in four healthy m en within a period of 3 days. uCPR, determined by isotope dilution of 11-oxoetiocholanolone was compared with sCPR, which was measured in th ree different ways (a, b, c). Blood was sampled at 10-min intervals fo r 24 h, and deconvolution analysis was applied to the cortisol concent rations. The daily serum cortisol production per liter, multiplied by the distribution volume yielded sCPR. The measurement methods are char acterized as follows: a) the secretion and elimination terms were free ; b) like method a, but with the input of the rate constants alpha and beta into the elimination function; c) the average 24-h cortisol conc entration was multiplied by the metabolic clearance rate. uCPR was 25. 4 +/- 4.7 [range: 21.3-31.4] mu mol/(m(2).day), sCPR (method a) was 28 .8 +/- 4.5 [range: 23.5-34.3] mu mol/(m(2).day), sCPR (method b) was 2 7.9 +/- 8.1 [range: 18.5-37.7] mu mol/(m(2).day), and sCPR (method c) was 29.3 +/- 4.8 [range: 22.7-33.2] mu mol/(m(2).day). uCPR did not si gnificantly differ from each of the 3 sCPR values (P > 0.30; >0.46; an d >0.06, respectively). The patterns of the cortisol secretory rates i n the present and previous studies do not necessarily represent the ph ysiological process of the secretory bursts. We conclude that the esti mated CPR, being 25-30 mu mol/(m(2).day) [9-11 mg/(m(2).day)], can ser ve as a guideline for glucocorticoid replacement dose and that the uri nary route to measure CPR is preferred because of its relative ease.