Sex distribution and severity of biochemical indices at the diagnosis of Cushing's disease (CD) were analyzed in 50 patients (21 males and 29 females; aged <or=30 yr; range, 6.4-30.0 yr). Twenty-five (50%) presented aged 18 yr or younger (17 males and eight females) and 25 aged 18-30 yr (four males and 21 females). CD diagnosed at less than 18 yr occurred predominantly in males, contrasting with 18 yr or older, which was more common in females. The difference between the two groups was significant (P = 0.0003). There was a significant difference (chi(2)) in sex distribution depending on pubertal status (P = 0.0002); in prepubertal patients (n = 11) males predominated (91%) compared with postpubertal patients (n = 27), where females predominated (81%). In patients in puberty (n = 12), there was an equal sex incidence (50% males). In adult patients with CD, males have been reported to have more severe disease. We found no difference in hypercortisolemia or ACTH at diagnosis in males compared with females in the patients less than 18 yr of age [serum 0000 h cortisol, 510.5 +/- 75.2 vs. 415.6 +/- 63.7 nmol/liter (P = 0.52); plasma ACTH, 48.5 +/- 7.9 vs. 42.9 +/- 10.9 ng/liter (P = 0.54); percent suppression of serum cortisol during low dose dexamethasone suppression test, 57.2 +/- 8.6% vs. 33.5 +/- 13.1% (P = 0.14); high dose dexamethasone suppression test, 85.9 +/- 3.1% vs. 85.7 +/- 4.9% (P = 0.55); percent increase in cortisol after iv CRH, 180.3 +/- 15.3% vs. 189.9 +/- 20.3% (P = 0.67)]. In conclusion, female preponderance of CD in adult patients was not present in childhood. In patients 18 yr of age or younger, there was no difference in the severity of hypercortisolemia or ACTH at diagnosis between males and females.