ABSTRACT
Thyroid function tests were used to classify 38 fibromyalgia patients according to thyroid status. Results were consistent with euthyroidism (normal thyroid status) in 14 patients (36.8%), primary (thyroidal) hypothyroidism in 4 patients (10.5%), and central (hypothalamic or pituitary) hypothyroidism in 20 patients (52.6%). The percentages of primary and central hypothyroidism in this group of fibromyalgia patients are extremely higher than those for the general population. There was no statistical difference for the mean intensity of fibromyalgia symptoms (measured by visual analogue scales) and the mean tender point scores (measured with algometry) between any of the categories of patients. The mean algometer scores and symptom intensities being essentially the same for all three categories of patients may show that the mechanisms involved were due to the same abnormal process-inadequate thyroid hormone regulation of gene transcription. In primary and central hypothyroid patients, this would result from a frank hormone deficiency, and in euthyroid patients, possibly from cellular resistance to thyroid hormone due to mutations in the c-erbAβ1 gene.