Thyroid function in patients with fibromyalgia syndrome

Thyroid function was tested in 13 female patients with primary fibromyalgia syndrome (FS) and 10 healthy age matched controls by intravenous injection of 400 micrograms thyrotropin-releasing hormone (TRH). Basal thyroid hormone levels of both groups were in the normal range. However, patients with primary FS responded with a significantly lower secretion of thyrotropin and thyroid hormones to TRH, within an observation period of 2 h, and reacted with a significantly higher increase of prolactin. Total and free serum calcium and calcitonin levels were significantly lower in patients with primary FS, while both groups exhibited parathyroid hormone levels in the normal range.