Adrenarche was evaluated in five patients, aged 17.4 +/- 3 years, with combined pituitary hormone deficiency (CPHD), caused by a PROP-1 gene defect. Adrenocorticotrophic hormone (ACTH), cortisol and dehydroepiandrosterone sulfate (DHEAS) were determined prior to and following the administration of corticotropin-releasing hormone (CRH) in four of the five patients, while only basal values of ACTH, cortisol and DHEAS were determined in the fifth. In the four patients in whom a CRH test was carried out, the mean basal values of cortisol, ACTH and DHEAS were 289 +/- 140 nmol/l, 4.5 +/- 1.7 pmol/l and 0.26 +/- 0.36 micromol/l, respectively. The corresponding post-CRH peak values were 584 +/- 204 nmol/l, 12.7 +/- 3.9 pmol/l and 0.43 +/- 0.41 micromol/l. In the fifth patient, basal ACTH, cortisol and DHEAS values were 4 pmol/l, 411 nmol/l, and 2.33 micromol/l, respectively. Thus the basal and post CRH values of DHEAS (a marker of adrenarche) were low for age, while basal and post-CRH cortisol and ACTH values were within normal limits. For the interpretation of these findings two hypotheses can be proposed: 1) The PROP-1 gene is only expressed in the pituitary, and the role of PROP-1 is related to the maturation of the cells which synthesize the presumed adrenal androgen stimulating hormone (AASH). 2) The PROP-1 gene is also expressed in the adrenal cortex and, when defective, the zona reticularis does not function appropriately. Regardless of the interpretation