BACKGROUND: Magnesium represents the fourth most abundant cation in the body and plays an integral role in intracellular metabolism. Although magnesium deficiency states have been associated with a variety of medical conditions, the prevalence of hypomagnesemia has not been well studied, particularly in ambulatory settings.
METHODS: We performed a period prevalence study using 120 patients seen for routine medical care at an urban family medicine center. Chart reviews were completed for these subjects. We used univariate and multivariate analyses to correlate magnesium levels with demographic and clinical factors.
RESULTS: There was a 20% overall prevalence of hypomagnesemia among this predominantly female, African American population. The prevalence of hypomagnesemia was greatest among patients with a history of alcoholism (odds ratio [OR] = 6.00; 95% confidence interval [CI], 1.41 - 26.1) and among those having 1 or more of the following medical conditions: diabetes, hyperlipidemia, hypertension, renal disease, and asthma (OR = 4.69; 95% CI, 1.37 - 17.65).
CONCLUSIONS: The prevalence of hypomagnesemia among patients from this urban minority community exceeds that reported in previous studies of the general population. This may be reflective of greater comorbidity, diminished nutritional status, or poorer overall health among patients from this community. The association between hyperlipidemia and magnesium deficiency warrants further investigation.
Magnesium represents the fourth most abundant cation in the body and plays an integral role in more than 300 enzyme systems, including adenosine triphosphate metabolism.1 Magnesium deficiency has been reported to result in neuromuscular manifestations, psychiatric problems, derangements in calcium or potassium flux, and cardiac arrhythmias.2
The Atherosclerosis Risk in Communities study, a large epidemiologic study with more than 15,000 subjects observed for more than 5 years, reported that participants with hypertension, diabetes, or cardiovascular diseases had lower mean serum magnesium levels than patients who did not have these diseases.3 This study also demonstrated that serum magnesium levels and dietary magnesium intake were lower for black patients than for whites.3 Clinical conditions reported among patients with hypomagnesemia included alcoholism (24%), diabetes (38%), diuretic use for hypertension (7%), and chronic renal failure (7%).3 A variety of clinical disease states have been reported to be associated with magnesium deficiency, including hypertension, diabetes, hyperlipidemia, angina, acute myocardial infarction, congestive heart failure, hypokalemia, hypocalcemia, alcoholism, and diuretic therapy.3
In addition to the general population-based epidemiological evidence, several studies have reported a high prevalence of hypomagnesemia among varied patient populations. The prevalence of hypomagnesemia has varied widely in previous studies Table 1. The prevalence of low magnesium levels has been reported as 2.5% of a group of hospital employees and blood donors,4 6.9% of inpatients at a veterans’ hospital,5 and 25% of outpatients with diabetes.6 Acute physiologic stress also seems to represent an important factor, as 65% of postoperative intensive care unit patients were found to be magnesium deficient.7 Together, these studies suggest potentially unrecognized magnesium deficiency among selected patient subgroups.
On the basis of our review of the literature on magnesium deficiency, we designed a prevalence study of patients from an urban, predominantly minority community in New York State. Our goals were to (1) determine the extent of undiagnosed hypomagnesemia among these patients and (2) examine whether low magnesium levels were related to hypertension, diabetes, or other chronic medical conditions.
Methods
Design and Setting
Our prevalence study took place in a family medicine center located in an urban area in April and May of 1995. The family medicine center serves as a community-based ambulatory clinic operated by a consortium of tertiary-care hospitals and is also part of a university-based resident training program.
Patient Population
The study sample was developed through the consecutive enrollment of 120 nonpregnant patients aged 18 years and older who required routine blood work for purposes other than our study. All subjects sought ambulatory care at the family medicine center during the designated 2-month period. Use of dietary magnesium supplementation was not permitted.
Data Acquisition
Using the standardized ambulatory protocol, all patients were triaged on arrival and had routine vital signs taken, and a physician took a history and performed a physical examination. If it was determined that it was necessary to draw blood, informed consent was obtained to permit collection of 1 additional vial of blood to determine serum magnesium levels. Medical charts were also reviewed to abstract information on subject demographics (eg, age, sex, and race) and comorbid medical conditions. In particular, conditions noted to be common in low magnesium states were recorded, including hypertension, diabetes, cardiovascular disease, renal disease, hyperlipidemia, and asthma, as well as any other active medical problem. Use of diuretics, which has been reported to lower serum magnesium, was noted. Social habits (eg, use of alcohol, drugs, and tobacco) were also recorded.