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Making Sense Of Common Hormone Tests
Nov. 2, 2004
Last reviewed and revised by Faculty of Harvard Medical School on May 18, 2009
By Alice Y. Chang, M.D.
Brigham and Women's Hospital
Understanding any test result your doctor has sent you can be confusing. This is especially true for blood tests that measure hormone levels in women. Test results need to be interpreted based upon why your doctor ordered the test to confirm a suspected diagnosis, to rule out an unlikely but potentially serious disorder, to monitor your progress after changing therapy, etc. Keep in mind that no test is fail-proof. Even a straightforward test like a throat culture for strep is not 100% accurate.
With hormone testing, the result often falls into the gray area rather than strictly being normal or abnormal. This is because hormone tests have several inherent flaws. The first problem is that hormone levels go up and down, not only during the day, but throughout the month when a woman is having periods. Also, many hormone levels fluctuate with medications and illnesses. So a high or low level during an illness might be normal. Normal values may differ from one laboratory to the next.
In addition, many tests have specific problems associated with them. Below are the more common hormone tests and the difficulties with interpreting their results.
The two principal tests that doctors order to check for thyroid disease are blood tests for thyroid stimulating hormone (TSH) and free thyroxine (T4). Generally, the TSH, a hormone made in the brain's pituitary gland, is the best screening test for thyroid disease. TSH blood levels rise when the thyroid is not producing enough thyroid hormone and TSH is suppressed when the thyroid is making too much.
Most of the time, the TSH level indicates whether thyroid function is normal, overactive (hyperthyroid) or underactive (hypothyroid). However, under certain circumstances TSH can be high when you are very sick even though your thyroid is functioning appropriately. In that case, a blood test for your free T4 level will determine if the amount of circulating thyroid hormone is at the correct level.
In most labs, TSH levels range between 0.5 and 5.0 milli-international units per liter. However, many doctors now consider the normal range to be lower: 0.3 to 3.5. TSH levels greater than 10 usually indicate a hypothyroid state and the need to take thyroid medication. If your TSH is between 3.5 and 10, you and your doctor will decide on whether to start thyroid pills right away or repeat the test in a month or two.
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Male Hormone Levels
The male hormones include testosterone, androstenedione and DHEA-S (dehydroepiandrosterone sulfate). Although called male hormones, healthy women normally produce small amounts of these hormones. Your doctor may order a blood test for male hormone levels for very different reasons. In women with excessive facial and body hair, the test is ordered to see if the male hormone levels are too high. Inability to get pregnant is another reason the test may be ordered.
The problems with testing for male hormones arise when it is used to evaluate menopausal women who have low libido and low energy levels. First, blood testosterone test results in women are not as reliable as they are for men. The test was originally designed to look for testosterone deficiencies in men, not in women. Women have much lower levels of testosterone, so the available tests may not be sensitive enough to accurately detect womens testosterone levels. Second, experts disagree what low testosterone levels mean for menopausal women and whether treating with testosterone really helps these women feel better. Some studies show an effect while others do not.
When interpreting male hormone test results, you might be confused by the lab reports because different labs use different units. Its like measuring something in inches as opposed to yards. You may have to calculate out the normal level depending on the measurement. Read closely whether your result is in mcg or ng per ml, dl or L.
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The blood test for menopause must be timed correctly in women still having periods. Hormone levels should be measured on day 3 of your period because elevations of follicular stimulating hormone (FSH) are most reliable on that day. Because the FSH level goes up and down the other days of the month, it is too hard to tell what those levels mean. Also, your levels might go up and down from month to month if you are perimenopausal (making the transition to menopause). One month you might have menopausal levels, and the next month you ovulate normally. So you CAN GET PREGNANT until you stop having periods for more than a year.
For women having difficulty becoming pregnant, elevated FSH levels on day 3 of your period can predict your chances of becoming pregnant. Depending on the normal levels for your lab, your gynecologist can advise you if your elevation of FSH indicates a need for additional steps.
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These tests are done when there is a concern about high or low levels of corticosteroid hormone produced by the adrenal glands. High corticosteroid (or steroid) levels can lead to weight gain, easy bruising, violet-colored stretch marks, high blood pressure and diabetes. Low steroid levels lead to fatigue, weakness, low blood pressure, weight loss and abdominal pain. Steroid levels are highest first thing in the morning and drop later in the day. Therefore, it is most helpful to test this level at 8 a.m. rather than another time of the day. A better test for high steroid levels is actually a measurement of corticosteroid levels in a 24-hour collection of your urine.
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Don't be surprised if you are still confused about what your test results mean after you have read this and met with your doctor. All of our hormones normally remain balanced by an intricate system that requires proper function by multiple organs. Measuring the hormone levels gives clues to what's going on inside your body and sometimes definitive answers. When in doubt, you might choose to consult with a hormone specialist called an endocrinologist, or a gynecologist with expertise in complicated hormone problems.
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Alice Y. Chang, M.D. is a former instructor in medicine at Harvard Medical School. She is currently associated with University of Texas Southwestern Medical Center. Her clinical interests and experience are in the fields of primary care, women's health, hospital-based medicine and patient education.