Polycystic Ovarian Syndrome (PCOS)
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- Polycystic ovarian syndrome (PCOS) is a common endocrine disorder with heterogeneous manifestations that affects 6–10% of the U.S. population.
- Hyperandrogenism, insulin resistance, and anovulation, typically presenting as amenorrhea or oligomenorrhea
- Diagnostic clinical characteristics include menstrual dysfunction, infertility, hirsutism, acne, obesity, and metabolic syndrome. The ovaries are often polycystic on imaging.
- The etiology of PCOS is unknown but can be modified by lifestyle factors.
- System(s) affected: reproductive, endocrine/metabolic, skin/exocrine
- Synonym(s): Stein-Leventhal syndrome; polycystic ovary disease
- Condition may begin at puberty.
- Predisposes to and is associated with obesity, hypertension, diabetes, metabolic syndrome, hyperlipidemia, infertility, insulin-resistance syndrome, endometrial hyperplasia, and uterine cancer
- In the United States, 40% of women with PCOS are not obese.
- Incidence and prevalence are still highly debated due to a wide spectrum of diagnostic features: The National Institutes of Health (NIH) criteria require chronic anovulation in addition to clinical or biochemical signs of hyperandrogenism. The prevalence based on NIH criteria is 6.5–8%.
- Predominant age: reproductive age
- Predominant sex: females only
Etiology and Pathophysiology
- PCOS is a multifactorial functional disorder of unclear etiology.
- Recent evidence points to a primary role for insulin resistance with hyperinsulinemia.
- Increased GnRH pulsations in the hypothalamus lead to increased production of luteinizing hormone (LH) with limited production of FSH.
- Hyperandrogenism: Ovaries are the main source of excess androgens. Polycystic ovaries have thickened thecal layers, which secrete excess androgens in response to LH. LH receptors are overexpressed in thecal and granulosa cells of polycystic ovaries.
- Ovarian follicles: Abnormal androgen signaling may account for abnormal folliculogenesis causing polycystic ovaries.
- Insulin resistance: Women with PCOS have insulin resistance similar to that in type 2 diabetes. Elevated levels of insulin decrease sex hormone–binding globulin (SHBG), increasing bioavailability of testosterone. Insulin may also act directly on adrenal glands, ovaries, and hypothalamus to enhance androgen production. Insulin resistance also causes elevated insulin levels.
- Insulin resistance may cause the frequently associated metabolic syndrome and frank diabetes mellitus.
- Likely a combination of polygenic and environmental factors
- Implicated genes include DENND1A and THADA.
See “Commonly Associated Conditions”; cause and effect are difficult to extricate in this disorder.
None known; focus on early diagnosis and treatment to prevent long-term complications.
Commonly Associated Conditions
- Obstructive sleep apnea
- Diabetes mellitus
- Endometrial hyperplasia/carcinoma
- Fatty liver disease
- Mood disturbances and depression