Why Is Hormone Testing with Saliva Beneficial?
- Saliva testing is the most reliable way to measure free, "bio-available" hormone activity - hormones actually doing their job at the cell level. Most blood tests do not measure "bio-available" hormone levels.
- Saliva collection is painless - no needles. It negates the need for blood drawing, which often causes stress that can alter test results.
- Saliva collection is easy and can be done anyplace at your convenience.
Why Test Saliva Instead of Serum (Blood Tests) for Hormones
Confusion exists among medical professionals and the general public about the question of progesterone absorption. This confusion often hinges on a misunderstanding of the test used to measure progesterone levels in the body. Let us try to clarify the issue.
What a Blood Test Measures
"Blood" tests for progesterone refer to the serum or plasma concentration of progesterone. Plasma is the watery, non-cellular portion of the blood from which cellular components such as red blood cells and white blood cells, are excluded. Serum is the essentially the same as plasma except that fibrinogen has been removed. Serum and plasma, being watery, contain water-soluble (hydrophilic) substances such as water-soluble vitamins, carbohydrates, and proteins. Serum and plasma do not contain fat-soluble (lipophilic) substances.
For the purposes of this discussion, serum and plasma are interchangeable and I will refer to them as serum. Sex hormones such as progesterone, estrogen and testosterone are fat-soluble steroids similar to cholesterol. When you have a serum cholesterol measurement, you are measuring cholesterol bound to protein, which makes it water-soluble. (Recall that serum cholesterol is described as HDL or LDL cholesterol, referring to the proteins to which it is bound.)
How Progesterone Travels in Blood
The ovary-produced progesterone found in serum is also largely protein-bound. Protein-bound progesterone is not readily bioavailable to receptors in target tissues throughout the body. It is on its way to the liver to be excreted in bile. Only 2 to 5 percent of serum progesterone is "free" or non-protein-bound. This is the progesterone available to target tissues and to saliva. Thus, progesterone measured by serum levels is mostly a measure of progesterone that is not going to be used by the body. A serum test can be used to compare one woman's progesterone production to that of another woman, or to test how much progesterone is being made by a woman's ovaries.
When progesterone is given intravenously, 80 percent of it is taken up by red blood cell membranes that are fatty in nature and therefore available to fat-soluble progesterone molecules. Less than 20 percent will be found in serum. It is obvious that serum levels would not detect the great majority of the progesterone added to whole blood.
Compare our Saliva Hormone Tests:
sex and adrenal hormones (4x daily cortisol)
Basic Saliva (with 1x cortisol)
sex and adrenal hormones (1x cortisol)
no adrenals, only progesterone, estradiol and testosterone
For more information, please see the Saliva Collection Instructions included with your test kit or watch the saliva collection video.