Saliva Analysis

Saliva as a Diagnostic Medium for Steroid Hormones
Over the past 20-30 years numerous research studies have validated the use of saliva as a diagnostic medium to measure the biologically active fraction of steroid hormones in the bloodstream. Saliva is an excellent medium to measure steroids because it is a natural ultrafiltrate of blood, and steroids not bound by carrier proteins in the blood freely diffuse into saliva. Only about 1-10% of the steroids in blood are in the unbound or free form, and it is this fraction that diffuses into target tissues of the body, and into saliva. The majority (90-99%) of steroid hormones in the blood are bound to carrier proteins (cortisol binding globulin, sex-hormone binding globulin and albumin) and are unavailable to target tissues. The process of passive diffusion of non-bound (free) steroid hormones occurs because these small molecules are of a low molecular weight (less than 400 daltons) and are relatively nonpolar, thus enabling them to freely diffuse from blood to saliva. The steroid hormones that have been studied most extensively in saliva include estrogens (estradiol, estrone, and estriol), progesterone, androgens (DHEA, testosterone,DHT), and cortisol.

The free steroid hormones passively traverse into the cells in the salivary gland and flow with the fluid that passively accompanies NA+ that is pumped by the sodium/potassium ATPase mechanism. Thus, there is no change in hormone concentration with change in flow rate. Bound steroids are too large to diffuse freely through the salivary cells into the salivary gland lumen as there is a molecular weight cutoff of approximately 400 kd. Total blood hormone levels are not comparable to saliva levels and can only be loosely compared using the approximate ratio (1-10%) of free to bound hormones. (See table below). Saliva hormones remain stable for at least three weeks at room temperature without a preservative.

With the recent availability of saliva steroid hormone testing, the medical community has rapidly begun to accept saliva as a preferred method to blood for steroid hormone testing. Aeron LifeCycles Clinical Laboratory now provides the clinical community with state-of-the-art services for testing the steroid hormone content of saliva.

Clinical Utility
Baseline measurement of hormone levels in saliva provides an accurate assessment of climacteric changes for the peri and post menopausal woman. Natural hormone replacement therapy and the use of pharmaceutical products can be measured in saliva. Monitoring trough level (hormone level just prior to next dose) following a period of therapeutic intervention (2-4 weeks of continuous therapy) permits titration of individual hormone dosages to maximize clinical effect and minimize dose related side effects. The influence of precursor hormones thought to elevate primary hormones through an endocrine cascade can be evaluated.

In men and women, the age related decline of hormones such as testosterone, DHEA, and melatonin can be assessed and monitored.

Laboratory studies have established the expected ranges for normal, unsupplemented saliva hormone levels of DHEA and testosterone for each decade of life in both men and women. Hormone level change associated with prescription or over-the-counter supplementation can be evaluated and titrated to the desired level.

Changes in hormone levels associated with the different routes of hormonal administration (oral, transdermal creams, patches, subcutaneous, sublingual, transvaginal, suppositories, etc.) can be accurately measured in saliva. Therapeutic target ranges of free salivary hormone levels have been established by Aeron for transdermal, oral and patch therapy.

Test Methods
Hormones in saliva are assayed by radioimmunoassay which uses the competition between radioactive and non-radioactive hormone for a fixed number of antibody binding sites to determine the concentration present in the specimen.

Specimen Requirements
Saliva: 7 ml is requested. Following collection, saliva should be either frozen or shipped to Aeron within 1 day of collection. Saliva is stable at ambient temperature for at least 3 weeks and a specimen received within that time is acceptable.

Available Tests
Aeron has established methods and procedures to quantitate circulating levels of the following hormones:

        Estradiol         Estriol                   Testosterone      DHEA       Melatonin
        Estrone           Progesterone      DHT                      Cortisol

References
1) Ellison, P: Measurement of salivary progesterone. Ann N Y Acad Sci 1992;161-176
2) Lipson, S & Ellison P: Development of protocols for the application of salivary steroid analysis to field conditions. American Journal of Human Biology:1989;1:249-255
3) Dabbs JM, Salivary testosterone measurements: Collecting, storing and mailing saliva samples, Physiology & Behavior 1990;49:815-817
4) Vining RF, McGinley RA, The Measurement of Hormones in Saliva: Possibilities and Pitfalls, J Steroid Biochem 1987;27:81-94