Delta-4 pathway steroid profiling by isotopic dilution, liquid chromatography-mass spectrometry after human chorionic gonadotropin stimulation in serum of men with Klinefelter Syndrome

ABSTRACT Background: Klinefelter Syndrome (KS) is associated with primary hypogonadism. Recent studies demonstrate greater intratesticular testosterone (ITT) concentrations in KS than in controls. However, the steroidogenic reserve of the testis in KS has never been evaluated in detail. Only few and contradictory studies - mainly from the 80s of the last century - are available in the literature about stimulated serum steroid profile. Aim: To investigate whether an enzymatic block of steroidogenesis might explain hypogonadism in KS. Methods: 13 KS patients (34±8years) not receiving testosterone replacement therapy and 12 eugonadic controls (EC) (32±8years) were enrolled. Serum steroids were measured by Isotopic Dilution, Liquid Chromatography- Tandem Mass Spectrometry (ID-LC-MS/MS) at baseline and for 5 days after i.m. injection of Human Chorionic Gonadotropin (HCG), 5000 IU. Results: HCG raised significantly in serum of both KS and EC (ANOVA, p<0.001), without significant difference between the 2 groups (t-test, p=0.715). All Delta-4 pathway steroids showed a significant increase after HCG stimulation (ANOVA): progesterone (P) (p<0.001 in both groups), 17OH-progesterone (17OHP) (p<0.001 in both groups), androstenedione (A) (p=0.049 in SK and p<0.001 in EU), testosterone (T) (p<0.001 in both groups). The 17OHP/P ratio (p<0.001 in both groups) and T/A ratio (p=0.003 in KS and p<0.001 in EC) raised significantly after HCG. Comparison of response to HCG between patients and controls (t-test) resulted in significant differences for T (p=0.001), 17OHP/P (p=0.005) and T/A ratios (p=0.002). Conclusion: Leydig cells of KS patients are able to respond to HCG by increasing T production less than in EC. The different trend in the two groups of 17OHP/P and T/A ratios suggests a less efficient enzymatic activity of P450c17/POR and 17ßHSD3 in KS than in EC. This study supports a disturbed steroidogenesis in Leydig cells of KS. The simultaneous evaluation by ID-LC-MS/MS of both serum T and ITT levels after HCG in an experimental animal model of KS could help in clarifying the pathophysiology of hypogonadism in KS.