[Correlation of male libido with the levels of serum reproductive hormones].

OBJECTIVE: To investigate the correlation between male libido and the levels of serum reproductive hormones. METHODS: We collected the clinical data on 134 men complaining of low or decreased sexual desire at our clinic of andrology from January 2013 to July 2018. According to the scores on the 13-item Self-Rating Libido Scale for Males (SRLS-M), we divided the subjects into a low libido (n = 68) and a normal libido group (n = 66), none with thyroid and adrenal diseases, liver and kidney diseases, or administration of drugs affecting sexual function and reproductive hormones in the past two weeks. We compared the age, history and course of disease, SRLS-M scores, levels of serum T, E2, LH, FSH and PRL, and T/E2 ratio between the two groups, and analyzed the correlation of the parameters obtained with the SRLS-M scores of the patients by Pearson correlation analysis. RESULTS: Compared with the males of the normal libido group, the low-libido patients showed a significantly longer course of disease (［1.83 ± 0.44］ vs ［2.91 ± 0.08］ yr, P < 0.05), but lower SRLS-M score (31.47 ± 1.28 vs 19.56 ± 0.89, P < 0.01), T level (［17.51 ± 3.68］ vs ［11.46 ± 1.62］ nmol/L, P < 0.01) and T/E2 ratio (17.27 ± 3.94 vs 12.42 ± 1.38, P < 0.01). No statistically significant differences were found between the normal and low libido groups in age (［32.22 ± 2.29］ vs ［31.98 ± 2.19］ yr) or the levels of E2 (［103.97 ± 15.70］ vs ［94.45 ± 10.37］ pmol/L), FSH (［9.98 ± 5.26］ vs ［7.43 ± 3.84］ IU/L), LH (［5.70 ± 3.17］ vs ［5.20 ± 3.37］ IU/L), or PRL (［281.96 ± 82.68］ vs ［371.85 ± 243.38］ mIU/L). Pearson correlation analysis showed that the SRLS-M scores of the patients in the normal and low libido groups were positively correlated with the T level (r = 0.329 and 0.535, P<0.01) and T/E2 ratio (r = 0.542 and 0.603, P<0.01), and so was the T level with E2 (r = 0.743 and 0.644, P<0.01) and T/E2 (r = 0.387 and 0.618, P<0.01). The areas under the ROC curves for T, E2 and T/E2 were 0.660, 0.527 and 0.669, respectively. A T/E2 ratio of 12.15－15.73 exhibited a relatively high sensitivity (>0.5) and specificity (>0.5) in the diagnosis of low libido. CONCLUSIONS: The T level and T/E2 ratio are important factors, and E2 may also be a factor, influencing male libido, which, however, is more correlated with T/E2. A T/E2 ratio of 12.15－15.73 may be an indicator of normal libido, while a lower or higher T/E2 ratio may suggests low libido.