MAGNESIUM SUPPLEMENTATION IN PATIENTS WITH CONGESTIVE-HEART-FAILURE

Objective: To evaluate several potential clinical indicators of magnes ium status (diet, blood, urine, 24-hour load retention) in patients wi th congestive heart failure before, during, and after oral magnesium s upplementation. Methods: Twelve patients with New York Heart Associati on class II-III heart failure and 12 age and sex matched healthy contr ol subjects were supplemented with 10.4 mmol oral magnesium lactate fo r 3 months. For the determination of magnesium status, samples of whol e blood, serum, plasma, red blood cells, and urine (24-hour) were coll ected. Four-day dietary intake records were reviewed. A 4-hour TV magn esium load retention study was performed before and 3 months after mag nesium supplementation. A non-supplemented control group was similarly studied. Results: At baseline, magnesium intakes for all groups were below the RDA. No significant differences were seen in serum, plasma, ultrafiltrates of serum or plasma or red cell magnesium concentrations among groups over time. At baseline 5/27 subjects (19%) compared to 1 1/27 subjects (41%) after supplementation demonstrated normal magnesiu m retentions (<25%). Magnesium excretions among groups were significan tly different during supplementation. Percent magnesium retentions amo ng groups were not different. Conclusions: Supplementation with 10.4 m mol oral magnesium daily for 3 months did not significantly alter bloo d levels or magnesium retention; however, patients demonstrated lower retention of magnesium after supplementation. Differences in magnesium retention was not related to basal magnesium intake, blood levels or excretion. Unfortunately, even an intensive effort at characterizing m agnesium status did not identify a clinical indicator of utility for d ifferentiating patients with congestive heart failure before, during, and after 3 months of magnesium supplementation.