Pituitary-Thyroid Function after Cessation of Prolonged Thyroid Suppression

To the Editor: Vagenakis et al., in a recent report (N Engl J Med 293:681, 1975), and others¹ have suggested that the pituitary-thyroid axis returns to normal functioning about five or six weeks after cessation of prolonged thyroid-hormone-suppression therapy, and that that is the optimum time to retest thyroid function to look for possible hypothyroidism. We wish to describe a patient who seems to be an exception to this recommendation in that her thyroid-function tests appeared to be within normal limits at eight weeks after cessation of thyroid hormone therapy but two months later she was found to be. No extract is available for articles shorter than 400 words.