Introduction: Testosterone and dihydrotestosterone circulate in plasma unbound (free), strongly bound to sex hormone-binding globulin (SHBG) and weakly bound to nonspecific proteins such as albumin. The bioavailable fraction includes the free and weakly bound fractions. Testosterone is important in maintaining bone health status in men. The present study aimed to examine the correlation between bone density and plasma testosterone in Malaysian men of various age groups.
Materials and Methods: 240 Malay and and 309 Chinese men aged 20 years and above, residing in the Klang Valley consented to the study. Their bone density was represented by their calcaneal speed of sound (SOS) value measured using the CM-200 sonometer (Furuno, Nishinomiya City, Japan). Total testosterone levels were measured using the ADVIA Centaur (Siemens Healthcare Diagnostics, Illinois, USA), based on competitive immunoassay with direct chemiluminescent technology. Non-SHBG-bound and free fractions of sex hormones were calculated per Södergård et al. (1982)
Results: There were no significant differences in calcaneal SOS, plasma total, bioavailable and free testosterone between the Malay and Chinese men. Thus subsequent correlation studies were conducted on the overall sample population, i.e. a total of 549 men. The calcaneal SOS values declined progressively from age 40 and was lowest in men aged more than 70 years. The plasma total testosterone results were unremarkable. However, both the biovailable and free testosterone declined progressively from age 30 years, reaching the lowest value at age more than 70 years. Pearson’s correlation showed that bioavailable and free testosterone was significantly correlated with calcaneal SOS in Malaysian men, while total testosterone was not.
Conclusion: The decline in bone density with age in Malaysian men was significantly correlated with their plasma levels of bioavailable and free testosterone, but not with total testosterone.