Fibromyalgia (FM) is a chronic pain condition that shares many symptoms with iron deficiency anemia (IDA) and thalassemia minor (TM). According to criteria established by the American College of Rheumatology, FM is a chronic pain condition characterized by a history of widespread pain in all four body quadrants and the presence of 11 of 18 tender points on physical examination. The prevalence of FM in developed nations varies between 0.5 - 4%, and the disease has an increased prevalence in patients with rheumatic diseases like rheumatoid arthritis (RA), lupus erythematosus, Sjogren’s syndrome, osteoarthritis, and Behcet’s disease; the prevalence of the disease is increased in chronic diseases like diabetes mellitus.

Prior to the publication of this study, the prevalence of FM in patients with IDA or patients with TM was not known. The study described below was conducted to (1) determine the prevalences of FM in patients with IDA or TM, (2) identify any factors associated with the presence of FM, and (3) determine the prevalence of IDA in FM and evaluate IDA’s affects on the clinical findings of FM.

The study population consisted of 205 consecutive patients with IDA and 40 patients with TM who were admitted to the Internal Medicine Outpatient Clinic located in Edirne, Turkey. Also included were 196 patients with FM diagnosed at the Rheumatology Outpatient Clinic. The control group consisted of 100 hospital employees (89 females and 11 males). All patients and healthy subjects were obtained for the study during the period of 2003 to 2005.

Fibromyalgia was identified using the ACR 1990 diagnosis criteria. Blood samples were taken for various biochemical factors identifying IDA and TM. IDA was defined as a hemoglobin (Hb) level of less than 13.5 g/dl in men (normal male adult 13.5–17.5 g/dl) or less than 12 g/dl in women (normal female adult 12.0–15.5 g/dl) with serum ferritin less than12 ng/ml, low serum iron, raised total iron binding capacity, and transferrin saturation less than 16%. Interviews were conducted to obtain demographic information. Function and pain parameters associated with FM were determined using a wall analog scale and the FM Impact Questionnaire score.

Fibromyalgia was diagnosed in 36 patients (all females) with IDA (17.6%), 8 patients (seven females, one male) with TM (20%) and 6 patients (all females) in the control group (6%).The prevalences of FM in patients with IDA compared to patients with TM was significantly higher than in the control group ( p=0.006 and p=0.025, respectively). The ratio of females in the IDA group was higher than that in the TM group (22.5% vs. 9.3%, p=0.027). There was no difference in Hb and iron parameters between IDA patients with or without FM. Fibromyalgia diagnosed in patients with IDA was associated with female sex, marriage, and history of pica (p<0.05). The results of this study indicate that FM has an increased frequency in patients with IDA and patients with TM. In patients with IDA and TM, nonspecific symptoms may not be explained by only anemia, and FM may be present.

An increased prevalence of fibromyalgia in iron deficiency anemia and thalassemia minor and associated factors. Pamuk GE, Pamuk ON, Set T, Harmandar O, Yeşil N. Clin Rheumatol. 2008 Apr 11.

NAAC Expert Commentary:
Fibromyalgia (FM) is a very common chronic pain syndrome. The most current hypothesis for its pathogenesis is that FM patients have central sensitization, a situation in which their processing of afferent sensory input results in these patients experiencing greater distress than normal individuals. Functional MRI scanning during painful stimuli has demonstrated that FM patients display increased blood flow to different parts of the brain compared to normal controls. Other central sensitization syndromes include low back pain, temporo-mandibular pain, and muscle contraction headaches. Fibromyalgia occurs as a primary syndrome, and commonly accompanies systemic disorders such as rheumatoid arthritis and lupus.

The article by Pamuk et al from Turkey evaluates the prevalence of FM in iron deficiency anemia (IDA) and thalassemia minor (TM). This analysis is difficult, given that the diagnosis of FM requires the absence of comorbid conditions that might account for the symptoms attributed to FM (such as fatigue, diffuse pain, etc.). Furthermore, it is hard to imagine how the presence of anemia would affect central processing of pain signals, although there might be a connection which is unrecognized.

Physicians must avoid the trap of attributing symptoms of diffuse pain and fatigue to FM, when there is an unrecognized medical problem present, such as anemia, malignancy, congestive heart failure, etc. Pamuk’s association of FM with IDA and TM probably falls under the category of “True and Unrelated.”

Last Modified: June 4, 2008