From the Guidelines
Bioavailable testosterone is the most clinically relevant form of testosterone for assessing osteopenia, as it represents the fraction of the hormone that can enter cells and exert biological effects on bone. When evaluating patients with osteopenia, measuring bioavailable testosterone, which includes free testosterone plus albumin-bound testosterone, provides the most accurate assessment of testosterone's bone-protective effects 1. This is because low bioavailable testosterone is associated with decreased bone mineral density and increased fracture risk in both men and women.
Some key points to consider in the assessment and management of osteopenia related to testosterone levels include:
- Measuring serum total or free testosterone levels as part of the investigatory work-up for osteoporosis in men, as recommended by evidence-based guidelines 1
- Considering testosterone therapy in cases of symptomatic deficiency, based on a holistic assessment of the patient across bone, cardiometabolic, and sexual function, ideally in conjunction with endocrinology expertise 1
- Treating hypogonadal men with osteoporosis with established anti-osteoporosis medication, regardless of whether testosterone therapy is instituted, to most effectively reduce fracture risk 1
- Recognizing that consistently robust benefits of testosterone replacement therapy have not been demonstrated, and that the decision to recommend testosterone therapy should be made on a case-by-case basis, taking into account the individual patient's needs and risk factors 1
In terms of the specific forms of testosterone, it is worth noting that:
- Free testosterone alone may underestimate the available hormone, while total testosterone can be misleading if SHBG levels are abnormal
- Bioavailable testosterone, which includes free testosterone plus albumin-bound testosterone, is the most clinically relevant form of testosterone for assessing osteopenia, as it represents the fraction of the hormone that can enter cells and exert biological effects on bone 1
From the Research
Testosterone and Osteopenia
- Testosterone plays a crucial role in maintaining bone mineral density (BMD) in men, and its decline with age is associated with decreased BMD and increased risk of osteoporosis 2, 3.
- The relationship between testosterone levels and osteoporosis development is complex, and while some studies suggest a link, others have found conflicting results 2, 4.
- Testosterone replacement therapy (TRT) has been shown to improve BMD in hypogonadal men with osteopenia and osteoporosis, although its effects on preventing bone fractures are unclear 2, 5.
Free and Bioavailable Testosterone
- Both free and bioavailable plasma levels of testosterone decrease with age in males, and fracture risk is associated with low levels of these testosterone fractions 4.
- The importance of free and bioavailable testosterone in maintaining bone health is highlighted by studies showing that these fractions are more closely related to bone mineral density and fracture risk than total testosterone levels 4, 3.
Albumin and Testosterone
- While albumin is a major carrier protein for testosterone in the blood, its role in osteopenia and osteoporosis is not well established 4, 6.
- Studies have focused more on the importance of free and bioavailable testosterone in maintaining bone health, rather than the role of albumin-bound testosterone 4, 3.
Treatment and Prevention of Osteopenia
- Treatment options for osteopenia and osteoporosis in men include testosterone replacement therapy, bisphosphonates, and nutritional supplementation with calcium and vitamin D 4, 5.
- Lifestyle modifications, such as regular exercise and a balanced diet, are also important for maintaining bone health and preventing osteoporosis 4, 5.