Bulbocavernosus muscle area as a novel marker for hypogonadism

Late-onset hypogonadism, or androgen deficiency in the aging male, is a significant cause of morbidity in older men. Many men in the low normal or equivocal range for low testosterone level exhibit signs and symptoms of hypogonadism. Serum testosterone is an imperfect maker for hypogonadism as symptoms vary greatly within the low to low normal range in addition to variations among testosterone assays. Perineal ultrasound can be effectively used to examine the bulbocavernosus muscle (BCM), an androgenized tissue that may be impacted by androgen receptor activity.

This study was a retrospective analysis of men who underwent perineal ultrasound for hypogonadism. The ultrasound data were used to calculate the area of the BCM and correlate it with indices of hypogonadismin symptomatic men including free and total testosterone and dual-energy X-ray absorptiometry (DEXA).

The results demonstrate that there is a significant correlation between total and free testosterone and BCM area in hypogonadal patients. Comparison between BCM area and total testosterone showed R  = 0.061 and p = 0.0187 and comparison between BCM area and free testosterone showed R  = 0.0957 and p = 0.0034. In addition, low BCM was also correlated with DEXA results showing osteoporosis and osteopenia (R  = 0.2239, p = 0.0027).

There has been recent controversy over the safety of testosterone replacement therapy. This might be particularly important in men with hypogonadal symptoms but a low normal testosterone level. Our study investigated the use of perineal ultrasound to measure BCM as a surrogate marker for poor androgenized men presenting with hypogonadism.