Testicular Responses to hCG Stimulation at Varying Doses in Men with Spinal Cord Injury

Spinal Cord, 2017 · DOI: 10.1038/sc.2017.8 · Published: July 1, 2017

Simple Explanation

This study investigates testicular function in men with spinal cord injury (SCI) who often have low testosterone levels. The goal was to see if stimulating the testes with different doses of human chorionic gonadotropin (hCG) could help identify any gonadal dysfunction. The researchers administered three different doses of hCG (400 IU, 2000 IU, and 4000 IU) to men with SCI and able-bodied men, measuring their testosterone response over three days. The study found that men with SCI generally had a normal testosterone response to hCG stimulation, suggesting that their low testosterone levels are likely due to issues with the pituitary or hypothalamus rather than the testes themselves.

Study Duration

3 Months

Participants

30 men with chronic SCI and able-bodied (AB) men

Evidence Level

Prospective, open-label, parallel group investigation

Key Findings

1
The average gonadal response in the SCI and AB groups to each dose of hCG was not significantly different in the hypogonadal or eugonadal subjects.
2
The serum testosterone concentration increased significantly for each group regardless of the dose of hCG (i.e., 400 IU, 2000 IU and 4000 IU).
3
Stimulation of the testes with hCG in an incremental fashion in men with SCI demonstrated a normal response of testosterone, regardless of baseline gonadal status.

Research Summary

This study aimed to determine if low testosterone levels in men with spinal cord injury (SCI) are due to primary testicular dysfunction by testing their response to varying doses of human chorionic gonadotropin (hCG). The results indicated that the average testosterone response to hCG stimulation was similar in both SCI and able-bodied men, regardless of their baseline testosterone levels (eugonadal or hypogonadal). This suggests that the testes are generally functioning normally. The authors concluded that the low testosterone levels observed in men with SCI are likely due to secondary testicular failure, possibly originating in the hypothalamus. However, a small subset of individuals may have impaired testicular function contributing to their low testosterone levels.

Practical Implications

Diagnostic Approach

hCG stimulation tests may not be effective in identifying primary testicular dysfunction in SCI patients with low testosterone.

Treatment Strategies

Treatment strategies should focus on addressing potential hypothalamic-pituitary issues rather than directly targeting testicular function.

Further Research

Further investigation is needed to understand the central mechanisms that regulate testosterone production in men with SCI, potentially involving factors like inhibin and activins.

Study Limitations

1
The study acknowledges that not all subjects responded appropriately to gonadal stimulation at each dose of hCG administered.
2
The study mentions the possibility of a mild primary end organ disorder that may also be considered.
3
The study suggests further research is needed to evaluate the role of central regulation of gonadotropin function.

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