Magnesium status and its correlation with symptomatology in patients with fibromyalgia syndrome: A cross-sectional study

Objective: The symptoms of magnesium deficiency and fibromyalgia syndrome (FMS) overlap considerably. Data on magnesium status in FMS or on influence of magnesium deficiency on FMS symptoms is not very comprehensive and rather heterogeneous. Therefore, the aim of this study was to record the magnesium status of FMS patients as well as correlations of magnesium status with severity and symptoms of FMS. Materials and methods: In 100 FMS patients, magnesium concentrations in serum, whole blood, and erythrocytes as well as ionized magnesium in serum were measured, and the corresponding ratio to calcium was calculated. Severity and symptoms of FMS were recorded using validated questionnaires: American College of Rheumatology criteria (ACR), Fibromyalgia Impact Questionnaire (FIQ-G), patient health questionnaires (PHQ-15, PHQ-4). Results: Based on a conventional reference range for total serum magnesium (0.76 - 1.10 mmol/L), no apparent magnesium deficiency could be detected. However, using more modern reference values or target criteria (serum magnesium & GE; 0.85 mmol/L; serum magnesium-calcium ratio > 0.4), a prevalence of magnesium deficiency of 20.2 and 83.8%, respectively, was recorded. There were no clear correlations of magnesium status with severity and symptoms of FMS. Conclusion: The presence of magnesium deficiency in FMS patients could not be confirmed clearly, but modern parameters indicate a high proportion of patients with latent magnesium deficiency. Given the similarity of symptoms, a magnesium deficit should be avoided or treated in these patients in order to avoid an unnecessary aggravation of symptoms.