Screening heterozygotes for 21-hydroxylase deficiency among hirsute women: lack of utility of the adrenocorticotropin hormone test

Heterozygosity for 21-hydroxylase deficiency (21-OHD) was investigated in 174 adult hirsute women by using the sum of the incremental responses of serum 17 α-hydroxyprogesterone (17 α-OHP) and progesterone (P) (Δ 17 α-OHP+P), 60 minutes after a 0.25mg intravenous (IV) bolus of synthetic adrenocorticotropic hormone (ACTH). The distribution of 17 α-OHP+P in hirsute women was bimodal, allowing two subgroups to be distinguished. In one subgroup including 137 patients, the mode was similar to controls and all values were lower than 3ng/ml. Thirty-seven (21%) patients constituted another subgroup with values higher than 3ng/ml and could a priori have been considered as heterozygotes for 21-OHD. However, human leukocyte antigen genotyping provided no conclusive evidence that this subgroup included exclusively heterozygotes for the 21-OHD.