Hormones are found in blood, saliva, and urine. The most accurate way to determine hormone levels is by blood. Blood tests can determine both the level of the free hormone and the amount of hormone that is bound to its carrier protein. Blood tests can accurately determine deficiencies of a hormone, and can show if adequate replacement has been prescribed. The downside of a blood test is that hormone levels change from moment to moment and day to day. Thus the hormone level is evaluated only at the time of the blood draw.
Proponents of saliva testing argue that only the free hormone is measured which determines the level of active hormone available to tissues. A limitation of salivary testing is that when hormone levels are low, there may not be sufficient hormones in the saliva to measure. In addition, saliva can become contaminated if any blood is in the specimen. Many practitioners feel that saliva tests are extremely inaccurate and that hormone levels in the saliva are not consistent with levels in the rest of the body.
Unfortunately, none of the hormone tests can measure what is happening at the receptor site or measure the hormone levels in tissues. If proper hormone levels are not achieved, then the person is not getting the full benefit of the replacement hormone. Each person responds differently to a dose of hormones because absorption and metabolism of hormones varies among individuals. Additionally, hormone levels can be affected by the route of administration of the hormone.
When prescribing hormones for a woman, I recommend checking hormone levels in the blood before beginning, and then again eight to ten weeks later. It is important to take the hormone as prescribed in order to evaluate hormone levels. When hormone levels are checked, it is optimal to check the level approximately 2-6 hours after taking the hormone. This is when the hormone level is peaking. If patients are not feeling the desired effect of the hormone or are having abnormal symptoms, it is recommended to recheck the blood level of the hormone, so micro-adjustments can be made.