ACTH Stimulation Test for Late Onset (Nonclassic) 21-Hydroxylase Deficiency

Abstract

Indication

To evaluate for androgen excess in diagnosing nonclassic CYP21A2 deficiency. If Basal 17-hydroxyprogesterone (17 OHP) < 2 ng/ml, diagnosis is unlikely and ACTH stimulation may not be necessary.

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FormalPara Indication:

To evaluate for androgen excess in diagnosing nonclassic CYP21A2 deficiency. If Basal 17-hydroxyprogesterone (17 OHP) < 2 ng/ml, diagnosis is unlikely and ACTH stimulation may not be necessary [1, 2].

FormalPara Preparation:

Women are best tested in the early follicular phase of the menstrual cycle. It is recommended to hold glucocorticoids for 24 h prior to testing to avoid any effect on 17 OH progesterone level.

FormalPara Materials Needed:

Two (2) gold top tubes labeled as baseline and 60 minutesCortrosyn 250 mcgSyringes/needles

FormalPara Assay for 17 OHP:

Radioimmunoassay (RIA) .

FormalPara Interpretation:

With late onset 21-hydroxylase deficiency, the absolute value of 17-hydroxyprogesterone at 60 min sample is > 10 ng/dl [2, 3].

FormalPara Caveats:

• Baseline androgen levels return to baseline after 8 weeks of discontinuation of oral contraceptive pills (OCP) [4].

• There is not enough data in regards to the effect of OCP on 17 OHP levels after ACTH stimulation.

FormalPara Procedure:

Completed as outpatient.

• 1. Obtain baseline blood sample for (17 OHP) and cortisol.

• 2. Give cortrosyn 250 mcg IM.

• 3. At 60 min, obtain sample for (17 OHP) and cortisol.

ACTH stimulation	Cortisol	17-OHP
Basal
30 min
60 min