ABSTRACT
The kinetic features of 11-deoxycortisol (S) were studied in a 11 beta-hydroxylase deficient boy. After i.v. administration of 35 kBq [3H]S (11 pmol) together with 44 nmol [13C]cortisol all his urine was collected during the next 3 days. A recently reported kinetic model, by which the fate of radioactive cortisol (F) in the body can be described by analysis of only the urinary radioactivity, has been used to calculate the rate constants of S metabolism. The overall half-life of S in the circulation was 4.7 min, which is very close to a reported half-live of the rapid phase: 4.1 min determined from the plasma radioactivity. The time of maximal accumulation of S in the first metabolic pool--26 min is about one quarter of that found for F--109 +/- 20 min (n = 8). The half-live of the S metabolites in the body was 7.0 h, equal to that of F: 6.1 +/- 0.9 h (n = 8). Obviously S is taken up into the metabolic organs 4 times faster than F, but it is not metabolized faster. The production rates of S and F were 127 and 2.1 mumol/(m2*d), respectively, pointing to a severely deficient synthesis of F. However, from the urinary excretion of 3 alpha,21-dihydroxy-5 beta-pregnan-20-one in relation to 3 alpha,11 beta,21-trihydroxy-5 beta-pregnan-20-one it cannot be concluded that the synthesis of corticosterone was strongly impaired.
