From the Guidelines
Achieving euthyroidism through appropriate treatment of the underlying thyroid disorder is the primary step in managing bone loss in hyperthyroidism, and a DEXA scan is recommended at diagnosis to establish baseline bone mineral density (BMD) 1. When considering the management of bone loss in patients with hyperthyroidism, particularly with a DEXA scan, it is essential to understand that hyperthyroidism causes accelerated bone turnover, leading to reduced BMD and increased fracture risk 1. The treatment of hyperthyroidism to restore the TSH level to within the reference range preserves BMD, but normalization of bone turnover may be delayed for up to 1 year 1. Key aspects of managing bone loss in hyperthyroidism include:
- Achieving euthyroidism through appropriate treatment of the underlying thyroid disorder
- Using a DEXA scan to establish baseline BMD at diagnosis and monitor improvement 1-2 years after achieving euthyroidism
- Considering bisphosphonates as first-line therapy for patients with established osteoporosis or significant bone loss, with medications like alendronate (70mg weekly) or risedronate (35mg weekly) being common choices 1
- Ensuring adequate calcium supplementation (1000-1200mg daily) and vitamin D (800-1000 IU daily) as adjuncts to therapy
- Incorporating weight-bearing exercise into the treatment plan to stimulate bone formation
- Regularly monitoring thyroid function (TSH, free T4) every 3-6 months to maintain euthyroidism and optimize bone health outcomes 1. According to the most recent guidelines, DXA is recommended for osteoporosis screening or initial imaging of clinically suspected low BMD, and it is a clinically proven method of measuring BMD in the lumbar spine, proximal femur, forearm, and whole body 1. The World Health Organization (WHO) defines normal BMD as a T-score ≥ -1.0, low bone mass or osteopenia as a T-score between -1.0 and -2.5, and osteoporosis as T-scores ≤ -2.5 1. In patients with low bone mass, a fracture risk assessment tool, most commonly FRAX, is used to determine the need for pharmacologic treatment 1. Overall, managing bone loss in hyperthyroidism requires a comprehensive approach that includes achieving euthyroidism, monitoring BMD with DEXA scans, and providing appropriate therapy to prevent further bone loss and reduce fracture risk 1.
From the Research
Management of Bone Loss in Hyperthyroidism
- Hyperthyroidism is associated with accelerated bone turnover, low bone mineral density (BMD), and increased susceptibility to fragility fractures 2.
- The management of bone loss in patients with hyperthyroidism involves treating the underlying condition, which can be done with antithyroid medications, radioactive iodine ablation, or surgical thyroidectomy 3.
- A DEXA (Dual-Energy X-ray Absorptiometry) scan can be used to assess bone mineral density in patients with hyperthyroidism, and studies have shown that hyperthyroid patients have a generalized reduction in axial bone mineral density compared to controls 4.
Treatment and Bone Health
- Treatment of hyperthyroidism can improve or even reverse some of the adverse skeletal effects, but there is limited guidance on routine BMD assessment in hyperthyroid patients following treatment 5.
- A study using Mendelian randomization analysis found that excess genetic risk for Graves' disease, autoimmune thyroiditis, and hyperthyroidism does not increase the risk for low BMD and is not associated with fractures in the Caucasian population 5.
- The Korean Thyroid Association has developed a position statement on the evaluation and management of bone health in patients with thyroid diseases, particularly focused on endogenous hyperthyroidism and thyroid-stimulating hormone-suppressive therapy-associated hyperthyroidism in patients with differentiated thyroid cancer 2.
Considerations for DEXA Scans
- DEXA scans can be used to assess bone mineral density in patients with hyperthyroidism, and can help identify patients at risk for osteoporosis and fractures 4.
- However, a study found that routine screening for osteoporosis following definitive treatment of hyperthyroid states may not be necessary, as the genetic risk for hyperthyroid conditions was not associated with an increased risk of fractures 5.
- The decision to perform a DEXA scan should be individualized based on the patient's risk factors and medical history, and should be done in conjunction with other diagnostic tests and clinical evaluations 4, 2.