The endocrinologic abnormality of PCOS begins soon after menarche. Chronically elevated luteinizing hormone (LH) and insulin resistance are 2 of the most common endocrine aberrations seen in PCOS. The genetic cause of high LH is not known. It is interesting to note that neither an elevation in LH nor insulin resistance alone is enough to explain the pathogenesis of PCOS.[7,8,9] In vitro and in vivo evidence offer support that high LH and hyperinsulinemia work synergistically, causing ovarian growth, androgen production, and ovarian cyst formation.
Obesity, which is seen in 50% to 65% of PCOS patients, may increase the insulin resistance and hyperinsulinemia. One important caveat is that the correlation between hyperandrogenism and insulin resistance has been recognized in both obese and nonobese anovulatory women. Thus, it is important to realize that a nonobese patient may also have insulin resistance. However, the insulin levels in obese women are higher than their nonobese counterparts. Clinically, though, both groups will have evidence of hyperandrogenism and oligo-ovulation or anovulation.[6,7]
Insulin resistance can be characterized as impaired action of insulin in the uptake and metabolism of glucose. Impaired insulin action leads to elevated insulin levels, which causes a decrease in the synthesis of 2 important binding proteins: insulin-like growth factor binding protein (IGFBP-I) and sex hormone binding globulin (SHBG). IGFBP-I binds to IGFBP-II and SHBG binds to sex steroids, especially androgens. The triad of hyperandrogenism, insulin resistance, and acanthosis nigricans (HAIR-AN) syndrome appears in a subgroup of patients with PCOS.[6,10,11]
Acanthosis nigricans, a dark and hyperpigmented hyperplasia of the skin typically found at the nape of the neck and axilla, is a marker for insulin resistance. Acanthosis nigricans is usually found in about 30% of hyperandrogenic women. Figure 1 illustrates acanthosis nigricans evident in a patient's axilla.
Acanthosis nigricans in a patient's axilla. Photo courtesy of Stanford Lamberg, MD, Associate Professor, Dermatology, The Johns Hopkins Medical Institutions, Baltimore, Maryland.
Relationship Between Diabetes Mellitus and PCOS
Women with PCOS are at higher risk of developing diabetes mellitus type 2 because of the relative insulin resistance. Also, these women tend to develop diabetes earlier in life, around the third or fourth decade. It is generally recommended, because of the known long-term complications of diabetes, that these young women be tested early in life and followed closely. These women should be screened in early pregnancy, as they have an increased risk of developing gestational diabetes.[2,5,12]
Relationship of Cardiovascular Disease to PCOS
Women who are hyperandrogenic and hyperinsulinemic are at increased risk for dyslipidemia, coronary artery disease, hypertension, and diabetes mellitus. The most common lipid abnormalities found in obese PCOS patients are decreased high-density lipoprotein and elevated triglycerides. In addition to the lipid abnormalities seen in women with PCOS, these patients are 7 times more likely to have a myocardial infarction.[3,13] Because cardiovascular disease is the leading cause of death of among women, prevention is essential.
Topics in Advanced Practice Nursing eJournal. 2002;2(3) © 2002 Medscape
Cite this: Polycystic Ovary Syndrome: An Overview - Medscape - Jul 31, 2002.