[ tee-ess-aitch ]

TSH stands for thyroid stimulating hormone.

Low TSH levels can have different implications, and require a comprehensive evaluation.

In patients treated with thyroxine, low TSH due to suppressive therapy has been found to have a minimal impact on bone density, which is unlikely to necessitate a reduction in thyroxine dose.

In premenopausal women receiving levothyroxine for non-toxic goiter, TSH suppression had no effect on bone mass. However, patients with hyperthyroidism may experience side effects such as insomnia, heart palpitations, decreased bone density, and a fast heart rate.

In patients who underwent a total thyroidectomy and received levothyroxine to suppress TSH, no adverse effect on bone density was observed over a 6-year period.

It is important to note that low TSH levels with normal or low Free T3 and Free T4 levels may indicate pituitary or adrenal issues, rather than a thyroid issue, leading to underdosing of supplemental thyroid hormone and persistence of hypothyroid symptoms. Thus, a comprehensive evaluation, including TSH, Free T3 and Free T4, and symptoms is necessary to accurately diagnose and treat thyroid conditions. Optimal Free T3 and Free T4 levels, rather than TSH, should be targeted for symptom improvement. If TSH is overly suppressed, the underlying issue should be addressed in the pituitary and hypothalamic axis, rather than reducing the thyroid hormone dose.