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Magazine: Journal of Nutritional Medicine, Spring, 1994


Since patients with either fibromyalgia syndrome (FS) or low magnesium (Mg) levels can have fatigue, sleep disturbance and anxiety, it was necessary to determine if some patients with FS also have low Mg levels. Both red blood cell (RBC) and plasma Mg levels were measured in 100 consecutive FS patients and 12 osteoarthritis (OA) control patients. Compared to reference laboratory and OA controls, FS patients had significantly lower RBC Mg levels. The plasma Mg levels of FS patients were no different than the reference laboratory or OA controls. Some FS patients have low Mg levels, a problem that is potentially correctable.

Keywords: fibromyalgia, magnesium, fatigue, pain.


Patients with fibromyalgia syndrome (FS), also called fibrositis syndrome, often suffer from myalgias, fatigue, sleep disturbance and anxiety [1-3]. The same symptoms are found in patients with low magnesium (Mg) levels [4]. In fact, abnormalities of muscle activity have been shown in Mg deficiency using myothermography [5]. Since treatment with Mg has been shown to be of benefit in patients with tiredness [6] and in patients with chronic fatigue syndrome (CFS) [7], measurements of Mg in FS patients might prove helpful in identifying those FS patients most likely to benefit from Mg supplementation. In fact, recently there was a preliminary report of low Mg in FS patients [8]. Both plasma and red blood cell (RBC) Mg levels of FS patients were measured to increase the sensitivity of the investigation. RBC Mg levels have been shown to be a better predictor of the body's Mg status than plasma levels [9] and low RBC Mg levels have been shown to be present while plasma levels were normal [7]. FS is a chronic disorder whose symptoms may be exacerbated by latent Mg deficiency. Recognition of such a problem in some FS patients would thus be the first step in more successful treatment and the easing of the suffering of many thousands of patients.


One hundred consecutive patients who fulfilled the American College of Rheumatology ACR criteria for FS [3] were examined for Mg deficiency. There were 20 men (mean age 46, range 29-57) and 80 women (mean age 48, range 28-64) studied. The mean tender point count in the FS patients was 16.2 (of a possible 18). Dolorimetric measurements were performed on six typical tender areas and three control areas. The mean dolorimeter scores of the tender areas were: occiput, 2.8 kg; trapezius, 2.4 kg; second rib, 3.2 kg; paraspinous, 3.6 kg; lateral humeral epicondyle, 3.4 kg; medial knee fat pad, 3.0 kg. The mean dolorimeter scores for the control areas were: thumbnail, 5.6 kg; midpoint of the third metatarsal, 5.4 kg; forearm midpoint, 5.2 kg. Dolorimetry was performed using a Chantillon dolorimeter as described previously [10] and the areas studied were on the right side of the body. Twelve patients with uncomplicated monoarticular osteoarthritis (OA) (four hip; six knee; two shoulder) were also studied. There were three men (ages 44, 48, 53) and nine women (mean age 50, range 42-64) in the OA group. None were taking diuretics or uricosuric drugs. None were bulemic, anorexic or using laxatives inappropriately to our knowledge. No FS patient was cachectic or on a 'crash' diet at the time of the study. All had simultaneous plasma and RBC Mg studies drawn. The samples were drawn into a heparinized tube from a peripheral vein. The samples were immediately refrigerated and then transported to a reference laboratory (National Medical Services, Willow Grove, PA, USA) where the assays were performed. The plasma and RBC Mg levels using washed cells were determined by using direct dilution techniques and atomic absorption [11, 12] and results reported in mg dl[sup -1] (mumol l[sup -1]).


The mean RBC Mg level for the general population (reference laboratory) is 5.5 mg dl[sup -1] (2.3 mumol l[sup -1]) with a 'normal' range of 4.2 - 6.8mg dl[sup -1] (1.75-2.83 mumol l[sup -1]). The standard deviation (SD) is 0.65 mg dl[sup -1] (0.27 mumol l[sup -1]). In contrast, the mean Mg level of the FS population (100 patients) is 4.6 (1.92) with a range of 3.7-5.6 mg dl[sup -1] (1.54-2.33 mumol l[sup -1]) and SD of 0.48 (0.20). By using a comparison of means test, there was a statistically significant difference (z = 8; p < 0.001) between these two groups. The FS patient group contained 41 patients with a myofascial pain syndrome (MPS) diagnosed using criteria developed by Travell and Simons [13]. However, most FS patients (59 patients) did not have a concomitant MPS. There was no statistically significant difference between these two groups (z = 0.2; p > 0.05). While 15 FS patients had RBC Mg levels that were clearly below the 'normal' range (i.e. <4.2 mg dl[sup -1] (1.75 mumol l[sup -1])), anothev 48 FS patients had RBC Mg levels in the lower quartile (i.e. between 4.2 (1.75) and 4.85 (2.02)mg dl[sup -1] (mumol l[sup -1]) of this range. In addition to the reference laboratory controls, 12 patients suffering from uncomplicated OA were also studied. They had RBC and plasma Mg levels measured. Their mean RBC and plasma Mg levels were 5.3 mg dl[sup -1] (2.21 mumol l[sup -1]) and 2.0 mg dl[sup -1] 0.83 (mumol l[sup -1]), i.e. not significantly different than published controls (p > 0.4) but different from RBC Mg values of FS patients (p < 0.01).

The mean plasma Mg level for the general population (reference laboratory) is 2.05 mg dl[sup -1] (0.85 mumol l[sup -1]) with a 'normal' range of 1.6 -2.5 mg dl[sup -1] (0.67-1.04 mumol l[sup -1]) and a SD of 0.225 mg dl[sup -1] (0.09 mumol l[sup -1]). The FS patients had a mean plasma Mg level of 2.05 mg dl[sup -1] (0.85 mumol l[sup -1]) with a range of 1.7 -2.6 mg dl[sup -1] (0.71-1.08 mumol l[sup -1]) and a SD of 0.275 mg dl[sup -1](0.11 mumol l[sup -1]). There was no statistically significant difference between the two groups.


The clinician is often frustrated when treating FS patients since symptoms are numerous and solutions inadequate. The finding of a potentially reversible problem (i.e. Mg deficiency) in some FS patients is encouraging. This study, as well as a previous report [8], identified a subgroup of FS patients that may benefit from Mg supplementation. More importantly, this finding may inspire further investigation into other easily treated problems that may cause FS patients difficulty. For a disorder such as FS which has no cure, the correction of any other problem which may be an exacerbation or perpetuating factor may not only be of help to the patient but may be critical in getting the FS under reasonably good control. There is certainly precedent for such reasoning. Travell and Simons [14] have maintained for many years that MPS sufferers cannot be treated adequately unless perpetuating factors such as vitamin deficiencies, electrolyte imbalances, poor posture, etc. are eliminated or ameliorated.

The question of whether Mg deficiency is pathogenic or simply an epiphenomenon is not known and requires further study. However, to he able to identify a correctable problem in FS sufferers is certainly desirable. Thus, Mg deficiency should be considered in FS patients especially if they are not responding to conventional treatments [15, 16] as expected. It is important to note that the Mg deficiency in FS patients was discovered only when RBC Mg levels were measured. Thus, FS patients who are suspected of suffering from low Mg must be tested for both RBC and plasma Mg before Mg deficiency can be ruled out.


Many FS patients suffer from Mg deficiency. While the former condition can be treated but not cured and the latter is potentially corrigible, it is important to assess Mg levels in all FS patients for optimal management of their musculoskeletal problem.


[1] Smythe HA, Moldofsky H. Two contributions to understanding of the 'fibrositis' syndrome. Bull Rheum Dis 1977; 28: 928-31.

[2] Yunus MB, Masi AT, Calabro JJ, Miller KA, Feigenbaum SL. Primary fibromyalgia (fibrositis); clinical study of 50 patients with matched normal controls. Semin Arthritis Rheum 1981; 11: 151-71.

[3] Wolfe F et al. The American College of Rheumatology 1990 Criteria for the Classification of Fibromyalgia. Report of the Multicenter Criteria Committee. Arthritis Rheum 1990; 33: 160-72.

[4] Webb WL, Gehi M. Electrolyte and fluid imbalance: neuropsychiatric manifestations. Psychosomatics 1981; 22: 199-203.

[5] Howard JMH. Muscle action, trace elements and related nutrients. In: Chazot G et al., eds. Current Trends in Trace Elements Research. London: Smith-Gordon, 1989, 79-85.

[6] Johansson BW. Magnesium infusion in decompensated hypomagnesemia patients. Acta Pharmacol Toxicol (Copenhagen) 1984; 54: 125-8.

[7] Cox IM, Campbell MJ, Dowson D. Red blood cell magnesium and chronic fatigue syndrome. Lancet 1990; 337: 757-60.

[8] Abraham GE, Flechas JD. Management of fibromyalgia: rationale for the use of magnesium and malic acid. J Nutr Med 1992; 3: 49-59.

[9] Alfrey AC, Miller NL, Burkus D. Evaluation of body magnesium stores. J Lab Clin Med 1974; 84: 153-62.

[10] Romano TJ. Clinical experiences with post traumatic fibromyalgia syndrome. West Virginia Med J 1990; 86: 198-202.

[11] Tietz NW, ed. Fundamentals of Clinical Chemistry, 3rd edn. Philadelphia: WB Saunders, 1987, 17-18.

[12] Brown SS, Mitchell FL, Young DS, eds. Chemical Diagnosis of Disease. Amsterdam: Elsevier/North-Holland, Biomedial Press, 1979, 440.

[13] Travell JG, Simons DG. Background and Principles in Myofascial Pain and Dysfunction. The Trigger Point Manual. Baltimore, London: Williams and Wilkins, 1983, 18-19.

[14] Travell JG, Simons DG. Perpetuating Factors in Myofascial Pain and Dysfunction. The Trigger Point Manual. Baltimore, London: Williams and Wilkins, 1983, 103-64.

[15] Romano TJ. Fibromyalgia Syndrome. In: Taylor RB, ed. Difficult Medical Management. Philadelphia, London: WB Saunders, 1991, 259-66.

[16] Yunus M, Masi AT. Fibromyalgia restless legs syndrome, periodic limb movement disorder, and Psychogenic Pain. In: McCarty DJ and Koopman WJ, eds. Arthritis and Allied Conditions. A Textbook of Rheumatology, 12th edn, Vol. 2. Philadelphia, London: Lea and Febiger, 1993, 1383-98.



1 Faculty American Academy of Pain Management--Private Practice, Wheeling, WV 26003, USA; 2 Private Practice, Lakeland, FL 33813, US

Correspondence to: Dr Thomas J. Romano, Suite 201, Center 3, Medical Park, Wheeling, WV 26003, USA