SAT-177 Hypophosphatemia Is a Frequent Finding in Infertile Men and Is Associated With Low Semen Quality

Abstract Disclosure: S. Kafai Yahyavi: None. F. Bay Toft: None. N. Jørgensen: None. A. Juul: None. M. Blomberg Jensen: None. Background: Phosphate is available in fluid from all segments of the male reproductive tract in concentrations manyfold higher than in serum. However, the role of phosphate in male fertility is largely unknown. Here, the associations between serum phosphate, semen quality, and reproductive hormones were assessed in infertile men. Methods: A cross-sectional study of 1,488 men, referred due to infertility. Each man underwent a physical examination, had semen parameters assessed, and had blood analyzed prospectively for concentrations of phosphate, ionized calcium, alkaline phosphatase, PTH, 25OHD, and reproductive hormones. 246 were excluded due to serious comorbidities, leaving 1,242 for the analyses. Results: Infertile men have a high prevalence of mild (25.5%, 0.66-0.80 mmol/L), and moderate hypophosphatemia (10.9%, 0.32-0.65 mmol/L). The percentages of motile spermatozoa and progressively motile spermatozoa were lower in men with moderate hypophosphatemia than in men with mild hypophosphatemia or normophosphatemia (44%, 49%, 51%, p=0.040, and 32%, 35%, 41%, p=0.036, respectively). The total numbers of motile and progressively motile spermatozoa were also lower (13, 12, 18 million, p=0.009, and 9, 9, 14 million, p=0.006, respectively). Serum concentrations of total and free estradiol were highest in men with moderate hypophosphatemia (97.5 pmol/L, 96.2 pmol/L, 92.1 pmol/L, p=0.004, and 2.4 pmol/L, 2.3 pmol/L, 2.2 pmol/L, p=0.034, respectively). Conclusions: Hypophosphatemia is frequent in infertile men and is associated with lower number of motile sperm. The precise mechanisms through which hypophosphatemia may impact sperm motility remain to be clarified. Presentation: Saturday, July 12, 2025