A 45-year-old patient with subclinical hypothyroidism has a TSH of 6.2. What are the major risks of prescribing levothyroxine?

Prescribing levothyroxine for a patient with subclinical hypothyroidism, especially one with a TSH level of 6.2, involves several potential risks. Among these, accelerated bone loss is a significant concern, particularly in postmenopausal women. This occurs because thyroid hormones can influence bone metabolism; an excess may lead to increased bone resorption and decreased bone density over time, heightening the risk of osteoporosis and fractures.

Atrial fibrillation is another notable risk associated with levothyroxine therapy. Increased levels of thyroid hormones can lead to heightened heart rates and altered cardiac rhythm. In patients with pre-existing heart conditions or risk factors for cardiovascular diseases, the likelihood of developing atrial fibrillation may be increased when exposed to higher thyroid hormone levels from levothyroxine.

This combination of accelerated bone loss and the risk of atrial fibrillation underscores the importance of individualized patient assessment and monitoring when initiating levothyroxine therapy, particularly in patients with subclinical hypothyroidism. Adjusting the dose carefully while considering the patient's baseline risk factors can help mitigate these risks.