Testing for recovery of thyroid function after withdrawal of long-term suppression therapy

Many persons are given thyroid hormone for long periods without sufficient justification. We selected 45 patients whose chart reviews did not demonstrate a clear need for thyroid replacement. Thyroid hormone was withdrawn and blood samples taken for free thyroxine index and TSH levels at 2, 4, 6, and 8 weeks after thyroid withdrawal. At 8 weeks, 30 of the 45 were normal. A single TSH test 8 weeks after thyroid withdrawal appears to be the most efficient way to separate euthyroid from hypothyroid patients.