Bone quality, not density, is the issue with hypothyroidism

Most hypothyroidism patients are treated with thyroid hormones while the underlying cause, immune dsyregulation or a breakdown in the thyroid hormone pathway, is ignored. As a result they may suffer from the consequences of poor thyroid function, one of the most serious being compromised bone health.

When looking at bone health, it’s important to consider not just bone density but also bone quality. One may have good bone density but poor bone quality — in other words the bone’s architecture is weakly engineered.

Because of the interactions between thyroid function and calcium regulation, people with hypothyroidism tend to have higher than normal bone density, while those with hyperthyroidism lose bone density.

However studies have shown higher bone density does not correlate with more bone strength. In fact, they show that hypothyroidism is accompanied by an increased risk for fractures. That’s because what’s more important is how well the bone is constructed. The following features are included when assessing bone quality:

• Microarchitecture
• Accumulated microscopic damage
• Collagen quality
• Mineral crystal size
• Bone turnover

All of these qualities combined that allow bone to successfully resist fractures. Unfortunately no definite tests exist at this time to monitor bone quality, however managing a hypothyroid condition should be paramount when addressing bone health.

Studies have also shown that people with hyperthyroidism lose bone density and are at a higher risk for bone fractures, even if proper thyroid function has been restored. Similarly, people whose thyroid condition is improperly managed with the excessive or unnecessary use of thyroid hormones are also at risk for loss of bone density.

References

Kosinska A, Syrenics A, Syrenicz, et al. The influence of treatment of substituvie or suppressive doses of thyroxine on biochemical bone turnover markers. Ann Acad Med Stetin. 2005;51:94-97.

Lakatos P. Thyroid hormones: beneficial or deleterious for bone? Calcif Tisue Int. 2003 Sep;73(3):205-9.

Licata A. Bone density vs bone quality: what’s a clinician to do? Cleve Clin J Med. 2009 Jun76(6):331-6.