Introduction: Apart from the involvement of central serotonergic neurotransmission on lifelong premature ejaculation, interference of thyroid function has been speculated.
Aim: To study thyroid function in a large group of men with lifelong premature ejaculation (LPE).
Methods: Lifelong premature ejaculation was defined as an intravaginal ejaculation latency time (IELT) of less than 1 minute. Any consecutive man with LPE and no erectile dysfunction assessed by medical history and the International Index of Erectile Function (IIEF-5) was eligible for the study. Apart from the assessment of thyroid-stimulating hormone (TSH) also free thyroxin (f T4) was determined in case of a TSH of <0.3 mU/L or TSH of >4.0 mU/L (being the lower and upper limits of normal values, respectively). Blood samples were drawn throughout the day within office hours.
Main outcome measures: Thyroid-stimulating hormone and f T4.
Results: Included were 620 men; age (mean+/-SD) was 39.9+/-9.4 years (range 19-65). TSH concentrations from morning, early and late afternoon samples did not differ. The geometrical mean TSH concentration was 0.85 mU/L (95% confidence intervals: 0.82-0.90) with a coefficient of variation of 57.9%. Fourteen men had a TSH of <0.3 mU/L (2.2%), while five men (0.8%) of >4.0 mU/L. All men with an abnormal TSH had a normal f T4 (between 10 and 20 pmol/L). No relationship was found between age and TSH concentrations.
Conclusion: Thyroid-stimulating hormone distribution was analyzed in a cohort of Dutch men with lifelong premature ejaculation and no erectile dysfunction. According to statistical analysis, there appeared to be no interaction between this ejaculatory complaint and the prevalence of thyroidal dysfunction. However, further studies are needed to gain more insight into the role of thyroid dysfunction and regulation of ejaculation time.