METHODS:

Comparative effects of placebos and T3 were tested on four euthyroid fibromyalgia patients over a period of nine months. Each patient completed alternately two T3 phases and two placebo phases, the sequence depending on the medication with which each was randomly assigned to begin. The ABAB single subject crossover design enabled each patient to serve as her own control. Phase crossover was response-driven, based on changes in measures of mean tender point sensitivity by algometry, pain distribution by the percentage method, and mean symptom intensity by visual analog scales. Changes were evaluated by visual inspection of graphs and single subject statistical analyses. Traditional group comparison statistics were performed for changes on the Fibromyalgia Impact Questionnaire, the Zung's Depression Scale, and pain distribution according to the ACR criteria.

RESULTS:

Quantitative analysis of trends of repeated measures across phases showed significant improvement in fibromyalgia status in T3 phases compared to baseline and placebo phases. Testing throughout the 9-month study and at 4-month follow-up showed no clinically significant adverse target tissue effects. No patient met the diagnostic criteria for fibromyalgia by the end of the study.

CONCLUSION:

Repeated administration and withdrawal of T3 corresponded to significant improvement and deterioration in fibromyalgia measures during this study. It is highly probable, then, that improvement in fibromyalgia status of our four patients was functionally related to their use of supraphysiologic dosages of T3 (effective range: 118.75-to-162.50 meg). These dosages were shown to be safe at 4-month follow-up. Further testing is necessary to establish long-term safety.

KEY WORDS:

Fibromyalgia, hypothyroidism, euthyroid, thyroid hormone resistance, T3