Dehydroepiandrosterone (DHEA) Saliva Luminescence Immunoassay

Luminescence immunoassay for the in-vitro-diagnostic quantitative measurement of active free DHEA in human saliva and total DHEA in diluted serum. DHEA (Dehydroepiandrosterone) and its sulphate ester DHEA-S, as C-19 steroid hormones, belong to the group of androgens. As they are almost exclusively (96 %) produced in the adrenal cortex, they are the most important adrenal androgens. Additionally, they are also produced in the gonads and in the brain. Due to quantity produced, they can be considered as the main products of human steroid biosynthesis. DHEA-S circulates in blood in 20-fold higher concentrations than any other hormone. The concentration of DHEA-S exceeds the DHEA levels by approximately 300 to 500 times. It serves as a kind of repository form of DHEA. The conversion of DHEA-S into DHEA takes place very quickly and in almost all body tissues as the corresponding enzymes are available ubiquitously. While the hydrophilic DHEA-S represents the inactive pre-hormone, the lipophilic DHEA can be reabsorbed by the cells of the peripheral tissues, converted into androgens and estrogens and then released into circulation. Only free, non-protein-bound, DHEA can enter the cells and be converted. This is also the case for saliva, where only the free DHEA is transferred. Therefore, the concentration of biologically active DHEA can be measured easily and directly in saliva. In blood, DHEA-S and DHEA are loosely bounded to albumin. In saliva, only the free active hormone is found. The concentration of DHEA in saliva is around 1/30 of those in sera. The normal DHEA concentration changes significantly with age: At birth the DHEA values are very high, dropping sharply to barely measurable values, and remain at low levels until the 7th to 10th year of life, when the adrenal cortex matures and DHEA values begin to rise again. In adults, peak concentrations of DHEA within an individual are expected to be achieved between the 25th and the 35th year, followed by a slow but continuous decline until a low value around the 50th year and finally reaching, at advanced age, when 10-20% of the peak values are observed. This age-related decline of DHEA secretion is known as “Adrenopause” and is the result of a reduction of the production of DHEA in the adrenal cortex. In serum and in saliva DHEA values are observed to be pulsatile as with other steroid hormone with clear oscillation range around the middle value. Due to the pulsatile dynamics of steroid secretion repeated saliva sampling is recommended. Due to the ubiquitous occurrence of DHEA, its determination is useful in many fields of the medicinal diagnostics and in research, mainly in endocrinology and anti-aging medicine but also in neuroendocrinology and veterinary medicine. DHEA is a stress marker in ssychology and in sports.