Pregnenolone, LC/MS

 Pregnenolone, LC/MS - This test may be useful in differentiating among different types of congenital adrenal hyperplasia (CAH). This test may also be used to monitor progress and treatment after diagnosis.

CAH is a group of autosomal recessive diseases characterized by deficiencies of enzymes in steroid hormone production. These deficiencies cause imbalances of steroid intermediates and hormones. Clinical manifestations of CAH vary and depend upon the type of defect and severity of the impairment. Therefore, measurement of different steroid hormones can help in diagnosing CAH.

Pregnenolone is a precursor to all steroid hormones. It can be elevated in some rare types of CAH, including deficiencies of 3-beta hydroxysteroid dehydrogenase, 17-alpha-hydroxylase, and P450 oxidoreductase. Levels of pregnenolone (and all other steroids) can be low in lipoid adrenal hyperplasia.

This test is generally ordered after evaluation of 17 hydroxyprogesterone (test code 17180). 17-hydroxyprogesterone testing, included in newborn screening, is used to detect 21 hydroxylase deficiency (the cause of 95% of CAH). When symptoms and signs suggest CAH, but 21-hydroxylase deficiency and 11-beta hydroxylase deficiency are ruled out, pregnenolone can be measured to assist in diagnosing other types of CAH.

Preferred Specimen(s):

0.5 mL serum collected in a red-top tube (no gel)

Minimum Volume:

0.2mL

Methodology:

Chromatography/Mass Spectrometry