Lack of Circadian Pattern of Serum TNF-α and IL-6 in Patients with Fibromyalgia Syndrome.

The present study was designed to test the hypothesis of a circadian variation in circulating levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in women with fibromyalgia syndrome (FMS). Serum levels of IL-6 and TNF-α were measured at 4 h intervals of the day in 50 women with FMS satisfying American College of Rheumatology criteria for FMS (age 36.68 ± 9.89) as well as 50 healthy control women (age 32.82 ± 10.53). Serum TNF-α levels were substantially increased in patients with FMS but showed no circadian variation. In contrast, no difference in the levels of IL-6 was found. Moreover, there was also no circadian variation in both the groups of patients and controls. We conclude that no circadian pattern exists in the circulating levels of serum IL-6 and TNF-α in patients with FMS, although TNF-α levels are found raised in patients with FMS.