Basal 17-hydroxyprogesterone cannot accurately predict nonclassical congenital adrenal hyperplasia in children and...

This study explored whether using the suggested diagnostic serum basal level of 17-hydroxyprogesterone (6.0 nmol/L) would lead to underdiagnosis of nonclassical congenital adrenal hyperplasia.

We retrospectively studied 123 patients with nonclassical congenital adrenal hyperplasia, defined as an adrenocorticotropic hormone-stimulated 17-hydroxyprogesterone level of more than 45 nmol/L. Of these 13 had basal 17-hydroxyprogesterone levels of less than 6.0 nmol/L and 110 exceeded that level. The 42 controls had idiopathic premature pubarche. Clinical and laboratory data were reviewed and compared.

There were no differences between patients with 17-hydroxyprogesterone levels of <6.0 nmol/L or ≥6.0 nmol/L based on age at presentation, gender, anthropometric measurements, bone age advancement, age at glucocorticoid initiation and hydrocortisone dosage. Patients with basal 17-hydroxyprogesterone <6.0 nmol/L had significantly lower stimulated 17-hydroxyprogesterone levels (p = 0.02) and higher stimulated serum cortisol levels (p < 0.008). Children with nonclassical congenital adrenal hyperplasia and premature pubarche were clinically indistinguishable from controls with idiopathic premature pubarche. Androgen levels were significantly higher in the nonclassical congenital adrenal hyperplasia group.

A basal 17-hydroxyprogesterone threshold of 6.0 nmol/L was not a sensitive predictive marker for diagnosing nonclassical congenital adrenal hyperplasia. Children whose clinical presentation suggests nonclassical congenital adrenal hyperplasia should undergo diagnostic adrenocorticotropic hormone stimulation testing.