Blood Tests for PCOS

There are several blood tests that may be done to help diagnose polycystic ovary syndrome (PCOS). Examples include follicle-stimulating hormone, testosterone, prolactin, and other hormone level tests. However, none of these can confirm PCOS on its own.

PCOS is only diagnosed once other conditions that cause similar symptoms are ruled out. Blood tests can help with that, the results of which are considered alongside those of imaging studies and a pelvic exam.

If PCOS is diagnosed, additional blood tests to check for diabetes and high cholesterol—conditions that commonly occur in people with this syndrome—will be next.

This article reviews the various blood tests that may be done as your healthcare provider investigates the possibility that you may have PCOS. It also discusses the additional testing that will be ordered if you're diagnosed.

Pregnancy Test

If you've missed your period or have stopped menstruating, the first test your healthcare provider will likely do is a pregnancy test.

Like versions that use a urine sample, a pregnancy blood test looks for human chorionic gonadotropin (HCG), a hormone that is only present if you are pregnant.

If the pregnancy test is negative, your provider will move forward with other blood tests.

FSH/LH Blood Test

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are made by the pituitary gland, a pea-sized organ located at the base of your brain. FSH stimulates the growth of an egg follicle within the ovary, while the surge of LH triggers the release of the egg during ovulation. 

A diagnosis of PCOS used to made based on an LH-to-FSH ratio greater than 3-to-1 (3:1), but this is no longer the case. Many people with PCOS have persistently elevated LH levels throughout their menstrual cycles and otherwise normal hormone levels.

If your FSH is elevated, it could also indicate an unrelated condition called primary ovarian insufficiency.

17-Hydroxyprogesterone Test

The 17-hydroxyprogesterone blood test (17-OHP) detects a hormone made by the adrenal glands. It is involved in the production of the stress hormone cortisol.

The 17-OHP test is used to determine the presence of late-onset congenital adrenal hyperplasia, another medical condition that can mimic the symptoms of PCOS.

DHEA/Testosterone Blood Test

Dehydroepiandrosterone (DHEA) and testosterone are hormones called androgens. These hormones are responsible for secondary male sex characteristics and are the cause of many of the symptoms of PCOS, including acne, hirsutism (hair growth on the face, chest, and back), female-pattern baldness, and menstrual irregularities.

An elevation of testosterone is typical in people with PCOS, but it is possible to have a spontaneous outbreak of acne and hirsutism with normal androgen levels and still be diagnosed with PCOS.

Androgen irregularities are a guide to help diagnose PCOS, but they are not a smoking gun.

Thyroid Function Tests

A thyroid function panel of blood tests is used to rule out thyroid dysfunction as the cause of your menstrual irregularities. Thyroid-stimulating hormone (TSH) is also secreted by the pituitary gland and regulates the release of the two thyroid hormones: triiodothyronine (T3) and thyroxine (T4).

These two hormones regulate basic metabolic functions. Having low levels of either could cause menstrual changes similar to those experienced in people with PCOS.

Prolactin Test

Prolactin is a hormone made by the pituitary gland. Its primary role is promoting lactation. Elevated values of this hormone (hyperprolactinemia) can cause irregular menstruation (oligomenorrhea) or a total lack of menstruation, known as amenorrhea.

If your prolactin levels are elevated, your provider will test your thyroid function because untreated hypothyroidism can also cause elevated prolactin.

Your provider may also want you to have a magnetic resonance imaging (MRI) scan of your pituitary gland to rule out a tumor called a prolactinoma.

Testing For PCOS-Related Conditions

If you are diagnosed with PCOS, your provider will also screen you for type 2 diabetes and high cholesterol—two conditions that are common in people with PCOS.

Oral Glucose Tolerance Test

An oral glucose tolerance test (OGTT) measures your response to sugar. Insulin is the major hormone that regulates blood sugar (glucose) and how it's metabolized for energy.

For the OGTT, you'll first have a blood sample taken so that your starting blood sugar level is recorded. Then you will be asked to drink a sugary solution. Blood will be drawn again two hours later to see how well your body is clearing the glucose you ingested.

In people without diabetes, blood sugar levels should return to normal within two hours of drinking the solution. If not, the test can be indicative of prediabetes or diabetes.

Urine samples are sometimes collected as well.

Lipid Panel

A lipid panel measures all of the key values associated with high cholesterol, including total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and another type of lipid called triglycerides.

People with PCOS often have high cholesterol, which can increase their risk of heart disease and diabetes.

Summary

There is no single test that can diagnose PCOS. Instead, a provider needs to rule out other medical conditions that cause similar symptoms, and blood tests are just one part of this process.

When a person is diagnosed with PCOS, they also need to be tested for other conditions that are very common in people with the disease, such as diabetes and high cholesterol.

A Word From Verywell

Getting a PCOS diagnosis is a process. A healthcare provider may suspect one cause of your symptoms only to get test results that send them on another path.

Ruling out other conditions that may be causing your symptoms can take time, but know that this is not uncommon. Try to remember that with every test, you are one step closer to getting the proper diagnosis—and treatment.