[Comparison of the kinetics of the response of salivary and plasma 17-hydroxyprogesterone to the administration of HCG in men].

17-hydroxyprogesterone (17-OHP) time course response to hCG (5,000 IU) was studied simultaneously in the saliva and the plasma of 12 adult healthy men. In both fluids, 17-OHP was determined by radioimmunossay after chromatography on Sephadex LH-20 columns of diethyl ether extracts. The use of an iodinated tracer has greatly increased the sensitivity of the technique. Baseline levels in plasma and saliva were: 1.0 +/- 0.1 ng/ml (mean +/- SEM) and 24 +/- 2 pg/ml respectively. After hCG, a biphasic pattern was observed in both fluids with a similar early response but the peak elicited at 33 h in plasma was not observed in saliva where the levels were lower than those recorded at 24 h. At 48 h saliva 17-OHP increased again to levels similar to those at 24 h. Thus the 17-OHP pattern in saliva was the mirror image of that found in plasma. Since saliva steroids are believed to reflect the plasma non-protein bound fraction, this difference was assumed to be due to the decrease of the unbound fraction of plasma 17-OHP in the late afternoon as a consequence of the increase of the CBG-bound fraction since at that time cortisol levels are low. Indeed the ratios of saliva to plasma 17-OHP levels were found to be significantly correlated with plasma cortisol levels: r = 0.44 (p less than 0.01; n = 140). Thus the absence of the secondary peak at 33 h may be due to cortisol circadian rhythm. However the similar response in saliva at 24 and at 48 h after hCG was enough important to make reliable the evaluation of the endocrine testicular function so that saliva may be collected instead of plasma in the hCG stimulation test protocol.