Magnesium content of serum, circulating mononuclear cells, skeletal muscle, and myocardium in congestive heart failure.

Deranged magnesium concentrations in serum and cardiovascular structures have been implicated in the pathophysiology of hypertension, ischemic heart disease, arrhythmias, and sudden death. This study was conducted to determine the status and interrelation of serum and tissue concentrations of magnesium in patients with congestive heart failure, a clinical setting purportedly predisposed to the development of depleted levels of this cation. Magnesium concentrations of serum, circulating mononuclear cells, skeletal muscle, and myocardium were measured in 23 patients with heart failure on standard therapy. Two patients were hypomagnesemic (less than 1.6 meq/l). Poor or no correlations were found between serum and tissue magnesium concentrations and among the magnesium concentrations of the three tissues studied. Strong direct correlations were, however, noted between magnesium and potassium concentrations of the tissues examined. The prevalence of hypomagnesemia in this typical ambulatory heart failure population is relatively low (9%) and serum, circulating mononuclear cell, skeletal muscle, and myocardial magnesium concentrations correlate poorly with each other. Serum, circulating mononuclear cell, and skeletal muscle magnesium concentrations are thus of little predictive value in assessing the status of myocardial magnesium in humans with heart failure.