Effect of hydrocortisone dose schedule on adrenal steroid secretion in congenital adrenal hyperplasia

To explore the potential effect of dose schedule on the adrenal suppressive action of hydrocortisone in congenital adrenal hyperplasia, eight patients (six with 21-hydroxylase deficiency and two with 11-hydroxylase deficiency) were given five different dose schedules. Two of the schedules used single daily doses (morning or evening), two twice daily doses (two-thirds dose in the morning or evening), one and three equal doses at morning, noon, and night. Each dose schedule used the same total daily hydrocortisone dose (12.5 mg/m²/day), which is within the normal range of hydrocortisone production rate. Each schedule was given for 4 to 6 weeks. The different dose schedules caused the predicted alterations in the temporal pattern of adrenal steroid levels, with the greatest apparent suppression during the 2 to 4 hours after each dose. None of the schedules, however, caused significant differences in the mean 24-hour plasma concentration of 17-hydroxyprogesterone (21-hydroxylase deficiency) or 11-deoxycortisol (11-hydroxylase deficiency) or in the 24-hour urine pregnanetriol or 17-ketosteroid concentrations, either in the six patients undertreated at the dose of 12.5 mg/m²/day or in the two patients adequately treated. Nocturnal administration of all or a part of the daily dose did not improve adrenal suppression. These observations suggest that treatment of congenital adrenal hyperplasia with a once-a-day hydrocortisone dose schedule may be as effective as conventional multiple-dose schedules. Until this hypothesis has been tested by more extended clinical studies, however, we do not recommend a once-a-day schedule. Regardless of the dose schedule, the total daily hydrocortisone dose must be adjusted to achieve a normal rate of growth and bone age advancement.