What should patients avoid eating prior to a TSH test?

Patients should avoid consuming shellfish prior to a TSH (Thyroid Stimulating Hormone) test because shellfish can contain high levels of iodine. Iodine is a critical component for thyroid hormone synthesis, and fluctuations in dietary iodine can affect thyroid function tests, including TSH levels. High iodine intake prior to testing may lead to inaccurate results, potentially causing false elevations or reductions in TSH levels, which can mislead healthcare providers regarding the patient's thyroid function.

In contrast, lean meats, dairy products, and fruits do not have a significant impact on TSH levels and are generally safe to consume before the test. Therefore, avoiding shellfish helps maintain the integrity of the test results and ensures accurate diagnosis and treatment planning for thyroid-related conditions.