Reliable Free Steroid Hormone Testing in Saliva
By Dr. Wolfgang Ziemann: 3.10.06 in Endocrinology
1. Introduction: The exact measurement of hormone concentrations is important for the correct estimation of the hormone balance and endocrine function. This measurement traditionally is performed in blood/serum/plasma samples. Several hormones also can be analyzed in saliva. This technique offers several advantages. The sampling is non-invasive and can be done anytime, anywhere. Especially in the case of steroid hormones such as Cortisol, Testosterone, Progesterone, Estradiol, Estriol, and DHEA reliable saliva testing offers significant additional advantages. The diagnostic relevance is much higher than compared to serum/plasma analytics.
2. The hormone activity: Steroid hormones are almost completely bound to their specific binding globulins. This bound fraction is biologically inactive and is considered to be just a kind of hormone reservoir. Only less than 5% of the total hormones are free and represent the active fraction. This free fraction is therefore considered to be responsible for the hormone action. In serum or plasma the steroid measurement will result mainly in a number representing the concentration of the total inactive hormone. This total concentration at best gives only an approximate indication of the hormonal balance in cases of completely healthy and normal patients. In any case it would be very advantageous to just measure the free fraction of the hormones. This is exactly what we can achieve by testing salivary samples.
3. Episodic hormone secretion: Due to the episodic secretion pattern of steroid hormones any result based on a single sample is completely arbitrary. We only can expect reproducible and reliable results in cases of multiple sampling. Therefore we always recommend taking 5 samples within at least a 2 hour period. This is valid for serum/ plasma as well as for saliva. In contrast to blood this sampling strategy easily can be done in cases of salivary testing. Please note that there should not be any food intake several hours prior to saliva sampling. Optimally saliva should be collected while morning-fasting. Intake of water will not affect test results. Other liquids are not recommended.
4. Sampling device: As saliva contains only tiny amounts of protein non-polar analytes such as steroids tend to absorb to various plastic surfaces. Glass would tend to be the best material for saliva sampling and for the most part Polyethylene, although it is still in use in many laboratories worldwide, should be avoided. However there is an inexpensive polypropylene device available from Demeditec Diagnostics or other suppliers. It does not show any interference in saliva even in Progesterone testing, which is the most critical steroid.
5. Blood in saliva: Traces of blood might interfere with the results of saliva testing. It is therefore important that the salivary samples should not show any red colour. In cases of visible blood traces in saliva the sample should be discarded. After rinsing the device several times with tap water a new saliva sample can be taken but only after waiting for approximately 15 minutes.
6. Serum testing: Testing of steroids in serum or plasma in general is questionable. The result represents mainly the inactive hormone fraction and is arbitrary in cases of a single sample. In a relatively short time, usually less than half an hour, the concentration of the hormone in serum can easily change by the factor of 2 or 3. Due to the limited specificity of current (fully automated) routine methods serum testing is unreliable in low concentration ranges. This has been recently published in scientific literature. In obvious contrast to this saliva testing is the most reliable alternative in any concentration range of steroids such as Cortisol, Testosterone, Progesterone, 17OH-Progesterone, Estradiol, Estriol, and DHEA.
7. Summary: Saliva testing for steroid hormones by far is the most reliable and convenient method for measuring the hormone activity in endocrine disorders and in checking the hormonal balance. Routine testkits in ELISA technology now are available for an increasing number of steroids.
