ABSTRACT
Polycystic ovary syndrome (PCOS) affects about 4 to 6% of women of reproductive age
and accounts for at least 75% of hyperandrogenic patients. PCOS is diagnosed by the
presence of oligo-ovulation and hyperandrogenism after the exclusion of related disorders,
such as 21-hydroxylase-deficient nonclassic adrenal hyperplasia (NCAH). In turn, NCAH
is a homozygous recessive disorder, diagnosed by a corticotropin-stimulated 17-hydroxyprogesterone
(17-HP) level greater than10 ng/mL (30.3 nmol/L) and confirmed by genotyping of the
CYP21 gene. The prevalence of NCAH is approximately 50 times less than that of PCOS, affecting
between 1 and 10% of hyperandrogenic women, depending on ethnicity. However, it is
generally difficult to distinguish NCAH from PCOS solely on clinical grounds, as both
demonstrate varying degrees of hyperandrogenism and ovulatory dysfunction. Most PCOS
patients have insulin resistance, in contrast to those with NCAH. Likewise, polycystic
ovaries are observed in up to 40% of NCAH patients. Both disorders have a strong familial
component. The only method that allows the separation of NCAH from PCOS patients is
the measurement of 17-HP levels. In conclusion, PCOS and NCAH have differences in
prevalence and pathophysiology. However, because the disorders have significant clinical
and hormonal similarities, the measurement of 17-HP, preferably basally as a screening
method, should be incorporated into the evaluation of all hyperandrogenic patients.
KEYWORDS
Polycystic ovary syndrome - adrenal hyperplasia - hyperandrogenism