Why test saliva instead of blood, serum or urine for hormone levels?
With saliva, it is possible to get a good measure of the amount of hormone actually available to the tissues – termed ‘bioavailable’. This is because hormones must pass through tissue to get into saliva. Hormones in blood are often bound to proteins and may or may not be available to tissues. Consequently, blood and serum levels of hormones may not give the best picture of how hormones are behaving at the tissue level. In addition, there are some hormones that are not measurable in blood, serum or urine. The paper Salivary Hormone Analysis goes into detail on the scientific rationale for salivary hormone testing.
