Classic
congenital adrenal hyperplasia (CAH) is associated with impaired function of the adrenal cortex and medulla leading to decreased production of
cortisol and
epinephrine. As a result, the normal exercise-induced rise in
blood glucose is markedly blunted in such individuals. We examined whether an extra dose of
hydrocortisone, similar to that given during other forms of physical stress such as intercurrent illness, would normalize
blood glucose levels during exercise in patients with CAH. We studied hormonal, metabolic, and cardiorespiratory parameters in response to a standardized high-intensity exercise protocol in nine adolescent patients with classic CAH. Patients were assigned to receive either an additional morning dose of
hydrocortisone or placebo, in addition to their usual
glucocorticoid and
mineralocorticoid replacement in a randomized, double-blind, crossover design 1 h before exercising. Although plasma
cortisol levels approximately doubled after administration of the additional
hydrocortisone dose compared with the usual single dose, fasting and exercise-induced
blood glucose levels did not differ. In addition, no differences were observed in the serum concentrations of the
glucose-modulating
hormones epinephrine,
insulin,
glucagon, and GH and of the metabolic parameters
lactate and
free fatty acids. Although maximal heart rate was slightly higher after stress dosing (193 +/- 3 vs. 191 +/- 3 beats/min, mean +/- sem, P < 0.05), this did not affect exercise performance or perceived exertion. We conclude that patients with classic CAH do not benefit from additional
hydrocortisone during short-term, high-intensity exercise. Although this has not been tested with long-term exercise, a high degree of caution should be used when considering the frequent use of additional
hydrocortisone administration with exercise, given the adverse side effects of
glucocorticoid excess.