Serum iron and iron stores in non-anemic patients with fibromyalgia

The aim of the study was to assess iron serum levels and markers of iron stores in non-anemic fibromyalgia (FM) patients and to evaluate their impact on the prevalence and clinical manifestations of FM patients. Eighty-four patients with primary FM and 87 controls were investigated. Demographic and clinical data were collected from all participants. All patients completed the fibromyalgia impact questionnaire (FIQ). Patients evaluated the effect of the disease on their daily activity (DA) and judged the severity (DS) of the disease on a 0-10 scale. Venous blood was tested for serum iron, transferrin, ferritin, and soluble transferrin receptors (sTfR). Iron deficiency was defined if any of the following were present: serum iron <40 μg/dL, serum ferritin levels <10 ng/mL, or sTfR levels >28.1 nmol/L. Analysis at a cutoff level of serum ferritin levels ≤30 ng/mL and sTfR/ferritin ratio was also performed. Hemoglobin, iron, transferrin, sTfR, ferritin levels, and sTfR/ferritin ratios did not differ between the groups. The mean FIQ score was 57.13 ± 20.21 and the DA and DS scores were 6.79 ± 2.97 and 6.74 ± 3.09, respectively. No correlations were found between the parameters studied and the FIQ or its ten individual items. Thirty-eight controls (43.7%) and 23 FM patients (27.4%) had ferritin levels of ≤30 (p < 0.04). Within the FM group, lower levels were associated with lower total FIQ score and FIQ subscale scores. Patients with FM do not have reduced serum levels of iron or surrogate markers of iron stores. At present, there is no evidence to support iron supplementation in the treatment of FM.