Objective: The mechanism of adrenarche is controversial, and there have been competing claims that its origin is in the hypothalamo-pituitary axis or in the adrenal gland itself. ACTH is proposed inducer of adrenarche so patients with ACTH resistance due to be familial glucocorticoid deficiency syndrome provide a model to clarify the degree to which ACTH is involved in the regulation of adrenal androgen secretion during adrenarche.
Design: Random analysis of plasma adrenal androgens and urinary adrenal androgen output in treated patients with familial glucocorticoid deficiency.
Patients: Eleven patients (6 males and 5 females, aged 6.5-21.6 years, 4 prepubertal, minimum bone age 9 years) with familial glucocorticoid deficiency were studied. In 6, mutations, in the coding region of the ACTH receptor are the cause of their ACTH resistance. In the remaining 5 the receptor was normal.
Measurements: Physical examination, basal serum cortisol, basal plasma ACTH, serum cortisol after stimulation with 250 micrograms ACTH(1-24), plasma dehydroepiandrosterone-sulphate (DHEAS) and plasma androstenedione (A4), total urinary androgen excretion and single-stranded sequencing of the coding region of the ACTH receptor.
Results: DHEAS was undetectable in 8, and detectable but below the age-matched reference values in 3 patients. A4 was measured in 10 patients, and in 3 patients (2 in late puberty) was found to be subnormal whereas in the remaining 7 patients A4 was normal for age and pubertal stage consistent with the gonadal contribution to peripheral A4 levels. Significantly diminished output of urinary adrenal androgen metabolites in 3 patients confirmed the results found in serum. The lack of adrenarche was independent of the presence of a mutation within the ACTH receptor and of the severity of glucocorticoid deficiency. Despite adequate glucocorticoid replacement therapy ACTH levels remained elevated in 10 of the 11 patients.
Conclusions: Although reduced adrenocortical inner zone cell number may contribute to the lack of adrenarche, in some patients there appears to be a discrepancy between partial glucocorticoid deficiency and significantly diminished adrenal androgen secretion. These data imply a significant contribution of ACTH to the regulation of adrenarche in normal children either by having a priming effect on the adrenal gland or by acting in concert with other adrenal androgen stimulating factors.