A TIME-RESOLVED FLUORESCENCE IMMUNOASSAY FOR THE MEASUREMENT OF TESTOSTERONE IN SALIVA - MONITORING OF TESTOSTERONE REPLACEMENT THERAPY WITH TESTOSTERONE BUCICLATE

Monitoring of testosterone replacement therapy requires a reliable met hod for testosterone measurement. Determination of salivary testostero ne, which reflects the hormone's biologically active plasma fraction, is a superior technique for this purpose. The aim of the present study was to establish a new sensitive time-resolved fluorescence immunoass ay for the accurate measurement of testosterone levels in saliva and t o validate it by monitoring testosterone replacement therapy in eight hypogonadal men. A clinical phase I- study with the new ester testoste rone buciclate was performed to search for new testosterone preparatio ns to produce constant serum levels in the therapy of male hypogonadis m. After two control examinations eight male patients with primary hyp ogonadism were randomly assigned to two treatment groups (n = 2x4) and given single doses of either 200 mg (group I) or 600 mg (group II) te stosterone buciclate intramuscularly. Saliva and blood samples were ob tained 1, 2, 3, 5 and 7 days post injection and then weekly for three months. The time-resolved fluorescence immunoassay for salivary testos terone shows a detection limit of 16 pmol/l, an intra-assay CV of 8.9 % (at a testosterone concentration of 302 pmol/l), an inter-assay CV o f 8.7 % (at a testosterone concentration of 305 pmol/l) and a good cor relation with an established radioimmunsassay of r = 0.89. The sample volume required by this method is only 180 mu l for extraction and dup licate determination. The assay procedure requires no more than three hours. In group I (200 mg) testosterone did not increase to normal lev els either in saliva or in serum. However, in group II, androgen level s increased significantly and were maintained in the normal range for up to 12 weeks with maximal salivary testosterone levels of 303 +/- 18 pmol/l (mean+/-SE) and maximal testosterone levels of 13.1 +/- 0.9 nm ol/l (mean+/-SE) in serum in study week 6 and 7. The time-resolved flu orescence immunoassay for salivary testosterone provides a useful tool for monitoring androgen status in men and women and is well suited fo r the follow-up of testosterone replacement therapy on an outpatient b asis. The long-acting ester testosterone buciclate is a promising agen t for substitution therapy of male hypogonadism and in combination wit h testosterone monitoring in saliva offers an interesting new perspect ive for male contraception.