Polycystic ovary syndrome laboratory findings: Difference between revisions
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==Overview== | ==Overview== | ||
Measurement of the plasma levels of several hormones is helpful in supporting the diagnosis of PCOS and especially in excluding other disorders. Determining the LH/FSH ratio of 3:1 is virtually diagnostic of PCOS; however, a normal ratio does not exclude the diagnosis, as LH levels fluctuate widely throughout the course of a day. Other androgens are measured to screen for other virilizing adrenal tumors. Fasting blood glucose is measured to look for diabetes; screening for lipid abnormalities is also employed. Testosterone is measured to exclude a virilizing tumor. Prolactin is measured to exclude a prolactinoma. Thyroid-stimulating hormone (TSH) is measured to rule out hypothyroidism | |||
==Laboratory Findings== | ==Laboratory Findings== | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
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Overview
Measurement of the plasma levels of several hormones is helpful in supporting the diagnosis of PCOS and especially in excluding other disorders. Determining the LH/FSH ratio of 3:1 is virtually diagnostic of PCOS; however, a normal ratio does not exclude the diagnosis, as LH levels fluctuate widely throughout the course of a day. Other androgens are measured to screen for other virilizing adrenal tumors. Fasting blood glucose is measured to look for diabetes; screening for lipid abnormalities is also employed. Testosterone is measured to exclude a virilizing tumor. Prolactin is measured to exclude a prolactinoma. Thyroid-stimulating hormone (TSH) is measured to rule out hypothyroidism
Laboratory Findings
Electrolyte and Biomarker Studies
It is vital to note that not all women with PCOS have polycystic ovaries (PCO), nor do all women with ovarian cysts have PCOS; although a pelvic ultrasound is a major diagnostic tool, it is not the only one. Diagnosis can be difficult, particularly because of the wide range of symptoms and the variability in presentation (which is why this disorder is characterized as a syndrome rather than a disease).
- Standard diagnostic assessments:
- Blood testosterone level: free testosterone is more sensitive than total; free androgen index is often used as a substitute.
- Common assessments for associated conditions or risks
- Fasting biochemical screen and lipid profile
- 2-hour oral glucose tolerance test (GTT) in patients with risk factors (obesity, family history, history of gestational diabetes) and may indicate impaired glucose tolerance (insulin resistance) in 15-30% of women with PCOS. Frank diabetes can be seen in 65–68% of women with this condition. Insulin resistance can be observed in both normal weight and overweight patients.
- For exclusion of other disorders that may cause similar symptoms:
- Prolactin to rule out hyperprolactinemia
- TSH to rule out hypothyroidism
- 17-hydroxyprogesterone to rule out 21-hydroxylase deficiency (CAH). Many such women may appear similar to PCOS and be made worse by insulin resistance or obesity, but they can be greatly helped by adrenal suppression with low-dose glucocorticoid therapy.
- DHEAS
- Androstenedione
The role of other tests is more controversial, including:
- Fasting insulin level or GTT with insulin levels (also called IGTT). Elevated insulin levels have been helpful to predict response to medication and may indicate women who will need higher dosages of Metformin or the use of a second medication to significantly lower insulin levels. Elevated blood sugar and insulin values do not predict who responds to an insulin-lowering medication, low-glycemic diet, and exercise. Many women with normal levels may benefit from combination therapy. A hypoglycemic response in which the two-hour insulin level is higher and the blood sugar lower than fasting is consistent with insulin resistance. A mathematical derivation known as the HOMAI, calculated from the fasting values in glucose and insulin concentrations, allows a direct and moderately accurate measure of insulin sensitivity.
- LH:FSH ratio elevation; FSH normal or low, LH high. Measurement of LH and FSH is easy and fairly standard, but the pattern is not very specific and is seen in only a subset of patients; present in less than 50% in one study.[1]