ABSTRACT
Background. In a previous study, T3 was found to be highly effective compared to placebos in the treatment of euthyroid fibromyalgia. In this replication study, the comparative effects of placebos and T3 were tested with 4 euthyroid fibromyalgia patients. A randomized double-blind placebo-controlled crossover design was used.
Methods. Patients completed alternately two T3 phases and two placebo phases. The sequence for each patient depended on the medication with which she was randomly assigned to begin. Crossover from one phase to another was response-driven, based on changes in 3 measures of fibre-myalgia status: mean tender point sensitivity by algomctry, mean symptom intensity by visual analog scales, and pain distribution by the percentage method. Measurements taken repeatedly during each phase were used to determine when a patient's scores warranted a crossover. Patients also completed the Fibromyalgia Impact Questionnaire and Zung's Self-Rating Depression Scale at the end of each phase.
Results. Paired-samples t-tests showed a highly significant difference between scores in placebo and T3 phases. Serial ECGs throughout the 8-month study, and urine and serum calcium, phosphorus, creatininc, serum alkaline phosphatase, and bone densitometry at 6-month follow-up revealed no adverse effects from T3.
Conclusion. The highly significant difference between fibromyalgia measures in placebo and T3 phases, despite the small N, indicates a powerful therapeutic effect of supraphysiologic dosages of T3. Despite low TSH and free and total T4 levels, and high free T3 levels, there was no evidence of thyrotoxicosis. Long-term safety of T3 use by euthyroid fibromyalgia patients has not yet been established.