Introduction
A higher prevalence of hyperthyroidism in patients with premature ejaculation (PE) has been reported; treatment of hyperthyroidism in a small group of patients resulted in improved outcomes by means of patient-reported outcome (PRO) measures related to PE and the mean intra-vaginal ejaculation latency time (IELT) of the subjects (Carani et al., 2005; Cihan, Demir, et al., 2009; G. Corona et al., 2004). On the other hand, delayed ejaculation (DE) has been observed in a large proportion of hypothyroidism patients; the mean IELT is also improved with the treatment of the thyroid disorder itself (Carani et al., 2005). In the same decade, it has also been clarified that there is no association with very low prevalence rates between thyroid dysfunction and lifelong PE in patients with normal erectile function (Waldinger, Zwinderman, Olivier, & Schweitzer, 2005). The aforementioned findings led to recommendations such as “thyroid hormone disorders should be suspected in ejaculatory disorders” with low certainty (Buvat et al., 2010). However, evidence from animal studies supports the presence of at least modulatory effects of thyroid hormones on the ejaculatory reflex operated from the central nervous system (Cahangirov et al., 2011; Cihan, Murat, et al., 2009; Cinar et al., 2018). We aimed to clarify the clinical evidence supporting the possible causality between thyroid dysfunction and EjD and the scientific background that supports the investigation of thyroid function in patients suffering from EjD.