Expert contribution with the participation of Prof. Dr. Michael Zitzmann. Learn how testosterone deficiency in men affects bone health and increases the risk of osteoporosis and fractures.
Men's bone health is often not at the center of health discussions, but it deserves special attention, especially in men with hypogonadism. Hypogonadism, better known as testosterone deficiency, is widespread and can have significant effects on bone health. Studies indicate that between 10 and 40% of men are affected by a deficiency (Mulligan et al., 2008). In this article, we highlight the important connection between hypogonadism and bone health in men, and how a lack of testosterone can lead to a reduction in bone density, which increases the risk of fractures and osteoporosis (Fink et al., 2006).
Hypogonadism and Bone Health
Hypogonadism or testosterone deficiency is a condition characterized by low testosterone levels in the body (Traish et al., 2011). Testosterone, an important hormone from the androgen group, plays a crucial role in many physiological processes, including the maintenance and strengthening of bone structure. Men with hypogonadism often not only struggle with obvious symptoms such as reduced libido, fatigue, and muscle weakness (Sizar et al., 2024) but also with less visible but equally serious problems such as reduced bone density and thus increased bone fragility, also known as osteoporosis (Shigehara et al., 2021).
Furthermore, a lack of testosterone can lead to reduced muscle mass (Bhasin et al., 1997) and an increase in body fat (Wittert et al., 2003), which also affects bone loading and the risk of fractures. Lower muscle mass weakens the mechanical support of the bones, while increased body fat and thus increased body weight leads to higher stress on the bones.
You can also learn more about testosterone deficiency in our article “Testosterone Deficiency in Men: Causes, Symptoms, and Solutions”.
Osteoporosis and Fracture Risk
Osteoporosis, a disease characterized by weak and brittle bones, is often seen as a women's disease (General, 2004). But men, especially those with hypogonadism, are also at risk. Studies have shown that men with low testosterone levels have an increased risk of fractures, especially of the hip, spine, and wrist. These fractures can have serious health consequences and significantly impair quality of life (Golds et al., 2017).
Men with hypogonadism are particularly susceptible to a decrease in bone density, as testosterone plays an important role in maintaining bone mass (Narla & Ott, 2018). Without sufficient amounts of this hormone, bone stability decreases, leading to increased fragility. This increased fragility means that even minor impacts or falls can lead to serious injuries. Hip fractures are particularly concerning, as they often lead to longer hospital stays, reduced mobility, and an increased risk of further health complications (Fox et al., 1993).
The spine is also at risk, as fractures in this area can lead to chronic pain, restricted mobility, and deterioration of posture. Wrist fractures, which are often seen as less serious, can still cause significant impairments in daily life, especially if they occur repeatedly or do not heal properly. Prevention and early treatment of bone weakness in men with hypogonadism are therefore crucial to maintain their quality of life and avoid serious health consequences.
Testosterone and Bone Metabolism
Testosterone contributes significantly to maintaining bone density by stimulating the activity of osteoblasts, i.e., the cells that form bone, and inhibiting the breakdown of bone tissue by osteoclasts, the cells that break down bone (Mohamad et al., 2016). These two cell types play a central role in bone metabolism. Osteoblasts are responsible for forming new bone matrix and depositing minerals, thereby strengthening and densifying the bones. Osteoclasts, on the other hand, are involved in the resorption of bone tissue by breaking down old or damaged bone material.
A lack of testosterone can therefore lead to an imbalance in this delicate system (Narla & Ott, 2018). When testosterone levels drop, osteoblast activity decreases and osteoclast activity increases, leading to bone breakdown outpacing bone formation. This imbalance results in a decrease in bone density. Reduced bone density means that bones are less mineralized and thus less stable and resistant (Shigehara et al., 2021).
The important role that testosterone plays in regulating bone metabolism makes it clear why sufficient testosterone levels are crucial for maintaining a healthy bone structure. Men with hypogonadism, whose testosterone levels are chronically low, should therefore have their bone health monitored regularly and take measures, if necessary, to stabilize testosterone levels and maintain bone density.
Diagnosis of Osteoporosis in Hypogonadal Men
The diagnosis of osteoporosis in men with hypogonadism should be comprehensive and thorough. A key component of the diagnosis is measuring testosterone levels in the blood to determine the extent of hypogonadism. Ideally, this measurement should be taken in the morning when testosterone levels are highest (Brambilla et al., 2009). The German guideline of the German Association of Osteologists states that measuring testosterone levels is mandatory in osteoporosis or osteopenia. Furthermore, testosterone must be replaced in hypogonadism and osteoporosis, also from the perspective of osteologists (DVO Osteoporosis Guideline 2023, n.d.).
Another essential tool for assessing bone health is bone density measurement, also known as a DXA scan (Dual-Energy X-ray Absorptiometry). This non-invasive test measures bone density and helps detect early signs of osteoporosis or reduced bone density before fractures occur. The DXA scan provides precise information about bone density in various parts of the skeleton, especially the hip, spine, and wrist, which are most susceptible to fractures (Blake & Fogelman, 2007).
A comprehensive diagnosis should also include an assessment of vitamin D levels and calcium levels in the blood. Vitamin D is crucial for calcium absorption and bone health. A vitamin D deficiency can lead to reduced bone density and an increased fracture risk (Branch, 2023). Therefore, it is important to check vitamin D levels and correct them with supplements if necessary. In addition, other relevant blood parameters important for bone health should be examined. These include parathyroid hormone (PTH), which regulates calcium metabolism (Kroll, 2000), and bone turnover markers such as osteocalcin and C-terminal telopeptide (CTX). These markers provide insight into the activity of osteoblasts and osteoclasts and help assess the balance between bone formation and bone breakdown (Szulc et al., 2017).
Prevention and Treatment Strategies
There are various strategies to improve bone health in men with hypogonadism and reduce fracture risk:
- Testosterone replacement therapy (TRT): Testosterone replacement therapy (TRT) can help normalize testosterone levels and improve bone density. Large, placebo-controlled, double-blind studies have shown that men receiving TRT have increased bone density and a reduced risk of fractures. By restoring normal testosterone levels, osteoblast activity is stimulated and bone resorption by osteoclasts is inhibited, leading to an overall stronger and more resilient bone structure (Snyder et al., 2017 ; Fui et al., 2021). However, a study published only this year in The New England Journal of Medicine showed an increased fracture rate under TRT compared to the placebo group, starting from the beginning of the study. Bone density was not measured. It is assumed that increased physical activity in the untrained, older, hypogonadal men with probable osteopenia or osteoporosis caused this at the start of TRT. For this reason, it is particularly important for older men starting TRT to begin exercise carefully and under supervision and to consider the risk of falls (Snyder et al., 2024).
- Nutrition: A balanced diet rich in calcium and vitamin D is crucial for bone health. Calcium is the most important mineral for bone formation and strengthening, while vitamin D promotes calcium absorption in the gut and thus supports bone mineralization. Foods such as dairy products, green leafy vegetables, fish, and fortified foods can help provide these important nutrients. In cases where dietary intake is insufficient, supplements may be beneficial (Laird et al., 2010).
- Physical activity: Regular physical activity, especially weight-bearing exercises such as walking, running, and strength training, can promote bone strength and slow bone loss. These activities stress the bones and stimulate bone formation by promoting osteoblast activity. In addition, physical activity improves muscle strength, coordination, and balance, thereby reducing the risk of falls and thus the risk of fractures (Pinheiro et al., 2020).
- Medication: In some cases, medications such as bisphosphonates or denosumab may be necessary to inhibit bone resorption and increase bone density. Bisphosphonates work by reducing osteoclast activity and thus slowing bone resorption. Denosumab is a monoclonal antibody that inhibits the formation and function of osteoclasts, thereby also reducing bone resorption. These medications are particularly useful for men with advanced osteoporosis or a high risk of fracture (Watts & Diab, 2010).
- Lifestyle changes: Avoiding smoking (Trevisan et al., 2020) and excessive alcohol consumption, as well as managing chronic conditions such as diabetes or thyroid disorders, are also important factors in maintaining bone health. Smoking and excessive alcohol consumption can reduce bone density and increase the risk of fracture (Sampson, 1998). Managing chronic conditions is crucial, as certain diseases and their associated medications can have negative effects on bone health.
Our Conclusion, Your Knowledge
Testosterone deficiency is a major risk factor for reduced bone density and an increased risk of fracture in men. It is important for men to be aware of the potential effects of low testosterone on their bone health and to take appropriate measures. Regular monitoring of hormone levels and bone density, combined with preventive and therapeutic measures, can help maintain bone health and reduce the risk of fractures.
At Adon Health, we place great importance on educating men about the importance of bone health and helping them proactively manage their health. With the right diagnosis and treatment, men with hypogonadism can improve their bone health and lead an active, healthy life.
