Male seminal parameters are not associated with Leydig cell functional capacity in men

Abstract

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Association of age, hormonal, and lifestyle factors with the Leydig cell biomarker INSL3 in aging men from the European Male Aging Study cohort

“…Of the lifestyle parameters measured, and as shown earlier, 15,28,30 both higher BMI and WC appear to have a similar negative impact on INSL3, T, and cFT (Table 2). Although a different analysis, simply comparing the effect of obesity (BMI > 30) on the levels of INSL3, T, cFT, and SHBG for the phase 2 subjects also indicated a significant impact of obesity on INSL3, as well as on the other parameters (Figure S3); the impact is relatively smaller (‐9.4%) for the former than T (‐21.5%), cFT (‐14.5%), and SHBG (‐17.4%).…”

“…Interestingly, in the multiple regression analysis (Table 3), where we have attempted to account for all possible confounding interactions between parameters in the construction of explanatory models for INSL3 and T, FSH now becomes a positive factor in determining INSL3 levels. This was also observed for the younger cohort of Swedish military conscripts 28 and suggests a role for Sertoli cells in mediating the regulation of INSL3, although not of T.…”

“…In a recent study of a much more homogeneous cohort of military conscripts, all healthy and aged approximately 18 years, there was no significant correlation between INSL3 and the T/LH ratio 28 . This suggests that the two parameters indeed differ, with the former a more anatomical construct and the latter more physiological, also reflecting the cells’ sensitivity to LH.…”

Endocrine outcome and seminal parameters in young adult men born with hypospadias: A cross-sectional cohort study

“… 25 However, no relationship between seminal parameters and serum INSL3 have been found so far. 26 In this study, higher INSL3 levels were found in participants with reduced sperm concentrations, but this did not reach statistical significance.…”

The Physiology of Reproduction – Quo vadis?

“…For the male, for example, the WHO latest acceptable reference range for sperm concentration is 15-259 million per ml with progressive motility of 32-75% and for normal morphology is only > 4% (Cooper et al, 2010;WHO, 2010)! We have shown that the normal range for circulating insulin-like peptide 3 (INSL3), a measure of Leydig cell functional capacity (i.e., total number of Leydig cells in the testes compounded with their differentiation status) is 0.39-1.87 ng/mL (5%, 95% confidence intervals) in healthy young men (Anand-Ivell et al, 2021). This is a large variation, compared to other, comparable non-episodic health parameters, such as thyroxine (5.5-12.5 µg/dL) or haemoglobin (14.0-17.5 g/dL).…”