Assessment of the one hour adrenocorticotrophic hormone test in the diagnosis of attenuated 21-hydroxylase deficiency

Nonclassic congenital adrenal hyperplasia

Nonclassic congenital adrenal hyperplasia (NCAH) due to P450c21 (21-hydroxylase deficiency) is a common autosomal recessive disorder. This disorder is due to mutations in the CYP21A2 gene which is located at chromosome 6p21. The clinical features predominantly reflect androgen excess rather than adrenal insufficiency leading to an ascertainment bias favoring diagnosis in females. Treatment goals include normal linear growth velocity and "on-time" puberty in affected children. For adolescent and adult women, treatment goals include regularization of menses, prevention of progression of hirsutism, and fertility. This paper will review key aspects regarding pathophysiology, diagnosis, and treatment of NCAH.

Prevalence of 21-hydroxylase-deficient nonclassic adrenal hyperplasia and insulin resistance among hirsute women from Puerto Rico

OBJECTIVE

To determine the prevalence of 21-hydroxylase (21-OH)-deficient nonclassic adrenal hyperplasia (NCAH) and insulin resistance in hirsute women from Puerto Rico.

DESIGN

Cross-sectional prospective study.

SETTING

Clinical research center.

PATIENT(S)

100 consecutive untreated hirsute women.

MAIN OUTCOME MEASURE(S)

Fasting total T, free T, DHEAS, insulin, and glucose were measured, and a 60-minute acute ACTH-(1-24) stimulation for 17-hydroxyprogesterone (17-HP) was performed. A diagnosis of 21-OH-deficient NCAH was considered when the stimulated 17-HP level was >30.3 nmol/L. The glucose/insulin ratio was calculated as a measure of insulin resistance (normal value, > or =4.5).

RESULT(S)

Patients had a mean (+/-SD) age of 26.8+/-6.6 years; 82 were oligomenorrheic. Overall, 12%, 8%, and 60% of patients had elevated levels of DHEAS, total T, or free T, respectively. One patient was identified as having 21-OH-deficient NCAH. Eight women, none of whom had NCAH, were found to be hyperglycemic; four of these women had type 2 diabetes mellitus. Excluding hyperglycemic patients, a glucose/insulin ratio of <4.5, consistent with IR, was found in 51.7%.

CONCLUSION(S)

The prevalence of 21-OH-deficient NCAH among patients from Puerto Rico does not differ significantly from that reported for other non-Jewish, non-Hispanic white populations.

Screening for 21-hydroxylase-deficient nonclassic adrenal hyperplasia among hyperandrogenic women: a prospective study

OBJECTIVE

To prospectively establish the specificity, sensitivity, and positive predictive value (PPV) of a basal 17-hydroxyprogesterone (17-HP) level for the screening of 21-hydroxylase-deficient nonclassic adrenal hyperplasia (NCAH) among hyperandrogenic women.

DESIGN

Prospective observational trial.

SETTING

Tertiary care academic medical centers.

PATIENT(S)

Eight healthy controls, 20 patients with NCAH, and 284 consecutively seen patients with hyperandrogenism.

INTERVENTION(S)

All controls and patients with NCAH, and select patients with hyperandrogenism, underwent acute ACTH (1-24) stimulation.

MAIN OUTCOME MEASURE(S)

Specificity was determined by measuring 17-HP every other day during one menstrual cycle in 8 healthy women with normal ovulation (107 samples). Sensitivity was determined by measuring 17-HP between 7 and 9 A.M. and 3 and 5 P.M. on the same day in 20 patients with genetically confirmed NCAH. The PPV was determined by prospectively measuring 17-HP in 284 consecutively seen hyperandrogenic women at their initial evaluation. The diagnosis of NCAH was established by a stimulated 17-HP level of >10 ng/mL.

RESULT(S)

Among controls, 17-HP levels of <2, <3, and <4 ng/mL all had a specificity of 100% when obtained in the follicular phase; when obtained in the luteal phase, they had specificities of 53%, 82%, and 82%, respectively. Among patients with NCAH, 17-HP levels of >2, >3, and >4 ng/mL had sensitivities of 100%, 90%, and 90%, respectively, for the detection of the disorder when obtained in the morning, and sensitivities of 95%, 90%, and 85%, respectively, when obtained in the afternoon. Among the 284 consecutively seen hyperandrogenic women, the PPVs of the first and second 17-HP levels were 7.3% and 19% for a cutoff level of >2 ng/mL, 13% and 43% for a cutoff level of >3 ng/mL, and 33% and 40% for a cutoff level of >4 ng/mL, respectively.

CONCLUSION(S)

A basal 17-HP level is a useful screening tool for NCAH. A cutoff level of 4 ng/mL has maximum specificity and PPV, with little loss in sensitivity if testing is performed in the morning and during the follicular phase. However, a lower cutoff level (e.g., 2 or 3 ng/mL) is preferable if testing is performed at odd hours of the day, as is common in many practices, and maximum sensitivity is desired.