The process of testing hormone levels is scientifically complex and the question of whether to test or not test, and which testing method is superior over another is debated by many leading health providers and scientists alike. So as a consumer, who just wants help, this can be a frustrating topic. We would like to unravel the mystery and translate this information for you. A little like going back to science class without the grade!
We think that testing hormone levels is a good idea. We are first to admit, however, that more information is needed in the area of hormone testing, to fully understand hormone balance for each woman’s body. Even so, we are in favor of testing while using hormones, to serve as a guide to begin to understand and monitor your own unique body chemistry, as you work with a Health Provider to optimize your health.
Although some health professionals successfully use their patient’s symptoms to track and assess hormone balance, most prefer to confirm their observations with hormone testing. Testing is particularly valuable when using bioidentical (natural) hormone therapy, to avoid excesses and imbalances that may not be seen with symptom tracking and that could lead to adverse symptoms or conditions with long term hormone use.
Four types of body fluids are commonly used to test for hormone levels, which include blood serum or plasma (venipuncture), capillary blood (finger stick), saliva, and urine. There are advantages and disadvantages to measuring hormones in each of these body fluids. Testing of hormones in any of these body fluids can provide useful information about the hormonal status of the patient and help guide the health care practitioner in choosing the most appropriate hormone therapy.
The serum or plasma test is what most conventional doctors routinely order. It measures the hormones present in the watery or liquid part of the blood known as the plasma, or serum. For serum/plasma tests, blood is most commonly drawn from a vein in the arm. Most of the hormones measured in serum are bound tightly by binding proteins. Only about 1-5% of the hormones present in serum are actually in the free or bioavailable form, meaning this would be the fraction of hormones circulating in the bloodstream that would leave the blood and enter tissues. Most of the tests for serum/plasma measure the total amount of hormone present, which is not as reliable a reflection of the hormone that is actually available to the tissues (bioavailable). This is one of the limitations to serum hormone testing, you only know what is circulating, not what is unbound and ready for delivery to the cells for use. In other words, there may be a higher level of hormones present and active in the cells of the body than the test reveals. More sophisticated methods have been developed to measure the small fraction of “free” hormones in serum that would be available to tissues, but these tests have been subject to scientific criticism as they may not truly reflect the bioavailable hormone in blood.
Capillary Blood Tests (blood from finger stick)
Capillary Blood Tests use blood from a finger stick rather than venous blood taken directly from a vein in the arm. Capillaries are the smallest blood vessels, where oxygen- and nutrient-rich arterial blood is exchanged for carbon dioxide and wastes are picked up to be delivered to the venous blood. Capillary blood can be dropped onto a special filter card and allowed to dry. Dried blood spots have distinct advantages over capillary serum collection because hormones in the dried form are extremely stable (well past a month) at room temperature. The dried blood is also much easier to ship to the laboratory as it does not require ice packs. Blood spot tests were originally developed in the 1960s to screen newborns for phenylketonuria (PKU) with a heel stick. Since then many blood spot finger stick tests have been developed, for many uses.
Capillary blood spot testing is promising for simplicity of use. However, as blood (serum) remains the gold standard with most providers, many health professional are unaware of this testing option.
Saliva hormone testing has long been familiar to international researchers who needed a way to measure hormones and other biochemicals in remote areas of the world where blood testing was not practical. In the 1990s, saliva tests were refined and developed for use as home test kits for those who wanted a simple alternative to serum testing. When it was discovered that transdermal hormone use did not match the results from blood (serum) testing, saliva testing became widely used for testing hormone levels in women using hormone creams and patches. A saliva test involves simply spitting into a tube which is then mailed to the laboratory for analysis.
Bioavailable hormones in the bloodstream are filtered through the salivary glands and enter saliva, which is easily collected for hormone testing. Saliva testing has been labeled by some as inaccurate because hormone levels in transdermal (topical) cream users goes up much higher than it does in serum, which increases very little. This is the reason why many doctors are surprised they don’t see hormones increasing in conventional venous serum tests, but their patients are telling them the hormones are working.
Again, Saliva testing helps to measure the hormones that are actually available to use in the tissues.
Although urine is widely used to test for drug use, and for pregnancy tests, it is less commonly used to test hormones overall. Some doctors still use a 24-hour urine test to measure levels of cortisol, but the test is less often used to measure the sex hormones estradiol, progesterone, and testosterone.
The biggest problem with urine testing is in the specimen collection which can be messy and involves carrying around a container of urine for 24 hours. This 24 hour evaluation of total hormone output, particularly for cortisol, does not help the practitioner appreciate the pattern of cortisol use throughout the day, as seen with saliva cortisol testing 4 times throughout the day. At present, the easiest and most accurate test for cortisol is the 4-point saliva test.
Other problems with urine is that it is not a direct measure of bioavailable hormones, but measures hormones and their metabolites (byproducts) that have been excreted. An analogy would be measuring how much food people eat by going through their trash cans. Hormone levels in urine can be affected by many variables, including kidney function, diet, and drug use (of any kind).
Urine testing is still used by some doctors to track down how hormones are metabolized in the body. There are some women who may have hormone imbalance symptoms in spite of normal blood or saliva hormone tests, and this may be related to how their body processes hormones. The hormone metabolites that show up in urine can be a useful indicator of irregularities in hormone metabolism.
Hormones are Free or Bound in the Blood
The major differences in hormone tests have to do with how closely the hormone test reflects the amount of hormone that enters tissues to exert a biological response. Because the body tightly controls hormone levels, the majority of hormones in the blood (95 to 99%), as measured in serum or plasma tests, are not actually available to tissues Most hormones circulating in the bloodstream are tightly bound to proteins such as binding globulins and albumin, that in effect, sequester and neutralize them, keeping them from entering tissues. Only a small percentage (1-5%) of these hormones escape the binding proteins and enter tissues to exert a biological effect. These binding proteins play an important role not only in regulating how much of the hormone enters tissues, but also in preventing rapid depletion of the hormone in the bloodstream.
Bioavailable hormones, which are the most accurate measure of the amount of hormone directly affecting the body, correlate best with symptoms of hormone imbalance. For example, if a perimenopausal woman is experiencing hot flashes and vaginal dryness, chances are good she has an estrogen deficiency, and this is most likely to be accurately reflected in a test that measures bioavailable hormones.
How Hormones are Delivered Changes How they Travel in the Body
When people take hormones orally (e.g. pill or capsule), the hormones travel through the digestive system to the liver, where most of them are processed and excreted. When people use transdermal (through the skin) hormone delivery such as creams, patches, troches or suppositories, the hormones are absorbed, and most of them are quickly bioavailable.
If transdermal hormone creams or patches are put on fatty areas such as the buttocks or thighs, the hormones may sit in the fatty tissues for a longer period of time before entering the bloodstream.
Some hormones are better suited to transdermal use than others. For example, progesterone travels quickly and efficiently into the bloodstream, while cortisol travels slowly, and much of it may remain in the skin and fatty tissues. Because oral hormones have to go through the liver before they are delivered to the blood and then the tissues, this explains why it takes a 100 mg progesterone pill to deliver 20 mg to the body’s cells, and it takes 20 mg of progesterone cream to deliver 20 mg to the cells. It also explains why, when drug companies began using estrogen patches in the same doses as the pills, the incidence of strokes skyrocketed in women using patches because much more estrogen was being delivered through the patch. As a result, current estradiol patches contain only about 10% of the dose of oral estrogens.
For resources and information on testing facilities, click here for a listing.