Four 2003 Studies of Thyroid Hormone Replacement Therapies: Logical Analysis and Ethical Implications

Replacement" is the most widely used approach to thyroid hormone therapy. Clinical practice guidelines define replacement therapy as: adjustment of a patient's thyroid hormone dosage so that his or her TSH and thyroid hormone levels remain within current laboratory reference ranges. Overall, the endocrinology 4 specialty endorses T -replacement as the preferable approach to thyroid hormone therapy. 4 Four studies published in late 2003 compared the effectiveness of two types of replacement therapy, T 3 tests to hypothyroid infants after they had been on either T - or T /T -replacement therapy for six and then twelve months. Compared to healthy infants, hypothyroid infants on both types of replacement therapy had impaired psychomotor function. In reporting this specific result of the studies—that neither type of replacement therapy effectively relieved patients' symptoms or abnormal neuropsychological test results—three groups of people have misrepresented, perhaps inadvertently, the outcome: the endocrinology researchers who conducted the studies, the endo- crinologists who commented on them, and the journalists who reported them. Rather than reporting the specific 4 study result, these groups reported a false general conclusion: that no approach to T /T3 therapy (replacement 4 is the only one they tested) was more effective than T alone. This false general conclusion violates a rule of quality scientific reporting—that we precisely formulate our statements to accurately convey conclusions that we can validly deduce from the studies we report. 4 Oddly, based on the negative outcome of these studies, some endocrinologists advise that T -replacement should remain the treatment of choice for hypothyroid patients. Their advice, however, disregards two hu- manitarian imperatives: (1) The endocrinology specialty must officially and publicly concede that many patients continue to suffer from hypothyroid symptoms despite their use of replacement therapies. This is especially important in view 4 of other studies. The other studies suggest that for many patients, T -replacement therapy increases the in- cidence of potentially fatal diseases and boosts chronic drug use to control the patients' hypothyroid symptoms and those of the other diseases. (2) These patients must have access to alternate thyroid hormone therapies, especially TSH-suppressive therapies, that are safe and effective for them. These imperatives require that the endocrinology specialty now impartially consider approaches to thyroid hormone therapy other than replacement. Alternate thyroid hormone therapies are already in demand and in widespread use by hypothyroid patients 4 for whom T -replacement is ineffective. These patients, many clinicians, and some researchers report that the alternate therapies are far more effective for the patients than replacement therapies. The endocrinology specialty's objections to these other therapies have been either speculative or based on invalid conclusions from studies. This imposes an urgent scientific obligation on the endocrinology specialty: that it now open-mindedly reevaluate its objections to alternate thyroid hormone therapies. This is essential on both humanitarian and