Association between 25(OH)-vitamin D and testosterone levels: Evidence from men with chronic spinal cord injury

Abstract

Objective: As an independent linear association between 25-hydroxyvitamin D (25(OH)D) and testosterone levels is controversial, this study aimed to explore this topic in men with chronic spinal cord injury (SCI), who exhibit a high prevalence of both androgen and vitamin D deficiency.

Design: Forty-nine men with chronic SCI consecutively admitted to a rehabilitation program underwent clinical/biochemical evaluations.

Results: Deficiency of 25(OH)D (<20 ng/mL) was found in 36 patients (73.5%). They exhibited significantly lower total testosterone and free testosterone levels, higher parathyroid hormone (PTH) and HOMA-IR, a poorer functional independence degree, and were engaged in poorer weekly leisure time physical activity (LTPA). Significant correlates of 25(OH)D levels were: total testosterone, free testosterone, PTH, functional independence degree and weekly LTPA. At the linear regression models, lower 25(OH)D levels were associated with both lower total and free testosterone after adjustment for age, smoking, alcohol consumption, comorbidities and HOMA-IR. However, after full adjustment, also including functional independence degree, BMI and LTPA, only the association of lower 25(OH)D with lower free testosterone was still significant.

Conclusion: In men with SCI, 25(OH)D correlates with total and free testosterone and exhibits an independent linear association with free testosterone. Regardless of this independent link, hypovitaminosis D and androgen deficiency are markers of poor health, sharing common risk factors to take into account in the rehabilitative approach to patients with SCI.

Keywords:

• Androgen deficiency
• Hypogonadism
• Hypovitaminosis D
• Paraplegia
• Tetraplegia

Acknowledgments

This work was supported by Ministero dell'Università e della Ricerca (MIUR), Italy.

Disclaimer statements

Contributors AB designed the research, conducted the study, analyzed data and interpreted results, performed statistical analysis and wrote the manuscript; MRCV analyzed data; GF and SF revised the article critically and approved its final version; FF designed the research, analyzed data and interpreted results, wrote the manuscript, revised the article critically and approved its final version.

Funding None.

Conflicts of interest The authors declare no potential conflict-of-interest.

Ethics approval The study was approved by the ethics committee of ASL1 Avezzano-Sulmona-L'Aquila.