How is congenital adrenal hyperplasia (CAH) diagnosed?

Updated: Oct 06, 2020
  • Author: Thomas A Wilson, MD; Chief Editor: Sasigarn A Bowden, MD  more...
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Answer

The diagnosis of CAH depends on the demonstration of inadequate production of cortisol, aldosterone, or both in the presence of accumulation of excess concentrations of precursor hormones, as follows:

  • 21-hydroxylase deficiency: High serum concentration of 17-hydroxyprogesterone (usually >1000 ng/dL) and urinary pregnanetriol (metabolite of 17-hydroxyprogesterone) in the presence of clinical features suggestive of the disease; 24-hour urinary 17-ketosteroid levels are elevated

  • 11-beta-hydroxylase deficiency: Excess serum concentrations of 11-deoxycortisol and deoxycorticosterone, or an elevation in the ratio of 24-hour urinary tetrahydrocompound S (metabolite of 11-deoxycortisol) to tetrahydrocompound F (metabolite of cortisol); 24-hour urinary 17-ketosteroid levels are elevated

  • 3-beta-hydroxysteroid dehydrogenase deficiency: An abnormal ratio of 17-hydroxypregnenolone to 17-hydroxyprogesterone and of dehydroepiandrosterone to androstenedione

  • Salt-wasting forms of CAH: Low serum aldosterone concentrations, hyponatremia, hyperkalemia, and elevated plasma renin activity (PRA), indicating hypovolemia

  • Hypertensive forms of adrenal hyperplasia (ie, 11-beta-hydroxylase deficiency and 17-alpha-hydroxylase deficiency) are associated with suppressed PRA and, often, hypokalemia

  • Subtle forms of adrenal hyperplasia (as in nonclassic forms of 21-hydroxylase deficiency and nonclassic 3-beta-hydroxysteroid dehydrogenase deficiency): Synthetic corticotropin (Cortrosyn) stimulation testing demonstrates the abnormal accumulation of precursor steroids; nomograms are available for interpreting the results [5]


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