[Strategies in screening of nonclassical forms of congenital adrenal hyperplasia caused by P450c21 deficiency in hyperandrogenic women].

BACKGROUND

The value of the measurement of the serum level of 17-hydroxyprogresterone (170HP) and the stimulation test with adrenocorticotropin (ACTH) with and without previous slowing with dexamethasone was determined to detect congenital adrenal hyperplasia (CSH) due to a deficiency of P450c21 in hyperandrogenic women.

METHODS

Three hundred seventy women consecutively attended for hyperandrogenism were studied. Stimulation tests of 170HP were performed with 250 micrograms i.v. of synthetic ACTH with previous administration of 1 mg of dexamethasone in 191 of the patients. The test was performed without previous dexamethasone in the remaining 179 patients.

RESULTS

Nineteen patients with unclassical forms of CSH by deficiency of P450c21 were detected. Another 19 were considered as probable heterozygotes. The basal levels of 170HP with and without previous dexamethasone showed negative predictive value of nearly 100%, indicating the validity of their use in selecting patients for the stimulation test. No significant differences were seen in the increases of post ACTH 170HP observed between the tests carried out with and without dexamethasone.

CONCLUSIONS

The frequency of congenital adrenal hyperplasia by deficiency of P450c21 in the hyperandrogenic women studied was found to be 5.1%. The low frequency together with the predictive value of the basal concentrations of 170HP indicate that the systematic routine use of the ACTH test as a means of scrutiny of CSH in hyperandrogenic women is unjustified.