Test and analyte info:
The very small concentrations of salivary hormones (only 1–5% of the total hormone levels that include protein-bound hormone found in serum) necessitate extremely sensitive assay methods. This is a particular issue for estrogens, which are present in very minute quantities in saliva, especially in older populations such as postmenopausal women. Extraction removes contaminants that interfere with the assay and concentrates the sample, significantly improving assay sensitivity compared to the “direct” assay methods available commercially. In fact, poor correlations between serum tests and non-extraction salivary estradiol assays have unfortunately led to some skepticism about saliva testing. Also, because of the extremely sensitive assays, it is important to avoid blood contamination of saliva as a result of oral injury; therefore tooth-brushing must be avoided before collecting saliva for testing. Saliva testing may also not be appropriate for sublingual hormone users unless samples are obtained at least 36 hours after the last dose. Blood spot testing is a preferred option for these patients.
Conversely, when some hormones, notably progesterone, are administered topically, saliva levels can rise higher than serum levels. This is because progesterone is carried on the surface of red blood cells to target tissues including the salivary glands, where there is rapid uptake and release of the hormone into tissues and saliva, leaving very little hormone in the venous blood returning from the tissues. Tissue levels of progesterone have been found to be very high after topical progesterone use, and a biological response can be demonstrated, e.g., the reduction of endometrial cell proliferation caused by estrogen therapy. Serum testing for progesterone therefore grossly underestimates the amount of progesterone that is being delivered to tissues when progesterone is applied topically to the skin.
DHEA-S, the sulfated storage form of DHEA, is measured rather than DHEA because its levels are more stable (DHEA has a much shorter half life in blood) and it has been found to correlate very well with reported clinical symptoms. However, as a conjugated hormone that does not diffuse into saliva as rapidly as the unconjugated hormones measured in other hormone assays, its passage into saliva is flow rate dependent and therefore flow stimulants such as gum chewing are not advised prior to saliva collection.
Research shows good correlations between salivary hormone levels and dosages of hormones given exogenously. Saliva testing is therefore a good option for monitoring hormone therapy and adjusting dosages if necessary.