Magnesium deficiency following jejunoileal bypass operations for obesity

Surgery for obesity

The medical risks of obesity increase exponentially as weight increases, and these risks are reduced by sustained weight loss. Behavior modification and dieting provide an approximately 6% loss of body weight at 1 year. Fenfluramine provides an approximately 8% weight loss at 1 year, which can be doubled to 16% when a drug such as phentermine, which works through a different biochemical mechanism, is added to it. This amount of weight loss is insufficient for many severely obese individuals. It was with these facts in mind that the National Institutes of Health Consensus Conference in 1992 recommended that obesity surgery is an appropriate treatment for patients with a body mass index greater than 40 kg/m2 who had failed in attempts at medical treatment and for patients with a body mass index greater than 35 kg/m2 with severe complications of obesity. Vertically banded gastroplasty and Roux-en-Y gastric bypass are the two operations presently recommended because of their relative safety and effectiveness. This article reviews previous procedures that have provided insight into the mechanisms by which these surgeries cause weight loss. The presently used surgeries and their results also are reviewed because until medical therapy improves substantially, surgery remains the most reasonable treatment option for most morbidly obese patients.

Evaluation of magnesium status in Crohn's disease as assessed by intracellular analysis and intravenous magnesium infusion

The magnesium status was evaluated in 30 subjects with Crohn's disease and in 30 controls. Subjects with Crohn's disease had lower concentrations of magnesium in muscle biopsy specimens (p less than 0.001), mononuclear cells (p less than 0.05), and in urine collected during 24 h (p less than 0.001) as compared with controls. After intravenous infusion of 60 mmol magnesium and 80 mmol potassium to 17 subjects with Crohn's disease a significant increase in concentrations of magnesium in muscle specimens (p less than 0.05), mononuclear cells (p less than 0.01), and plasma (p less than 0.01) was noted. The retention of intravenously infused magnesium was significantly higher in subjects with Crohn's disease than in 11 healthy controls (p less than 0.001) and was inversely correlated with the content of magnesium in muscle specimens (r = -0.52; p less than 0.05). The implication of these findings is that analysis of magnesium in muscle specimens and estimation of magnesium retention during an intravenous magnesium infusion are useful to confirm a suspected magnesium deficiency.

Magnesium metabolism in health and disease

Magnesium is an important element for health and disease. Magnesium, the second most abundant intracellular cation, has been identified as a cofactor in over 300 enzymatic reactions involving energy metabolism and protein and nucleic acid synthesis. Approximately half of the total magnesium in the body is present in soft tissue, and the other half in bone. Less than 1% of the total body magnesium is present in blood. Nonetheless, the majority of our experimental information comes from determination of magnesium in serum and red blood cells. At present, we have little information about equilibrium among and state of magnesium within body pools. Magnesium is absorbed uniformly from the small intestine and the serum concentration controlled by excretion from the kidney. The clinical laboratory evaluation of magnesium status is primarily limited to the serum magnesium concentration, 24-hour urinary excretion, and percent retention following parenteral magnesium. However, results for these tests do not necessarily correlate with intracellular magnesium. Thus, there is no readily available test to determine intracellular/total body magnesium status. Magnesium deficiency may cause weakness, tremors, seizures, cardiac arrhythmias, hypokalemia, and hypocalcemia. The causes of hypomagnesemia are reduced intake (poor nutrition or IV fluids without magnesium), reduced absorption (chronic diarrhea, malabsorption, or bypass/resection of bowel), redistribution (exchange transfusion or acute pancreatitis), and increased excretion (medication, alcoholism, diabetes mellitus, renal tubular disorders, hypercalcemia, hyperthyroidism, aldosteronism, stress, or excessive lactation). A large segment of the U.S. population may have an inadequate intake of magnesium and may have a chronic latent magnesium deficiency that has been linked to atherosclerosis, myocardial infarction, hypertension, cancer, kidney stones, premenstrual syndrome, and psychiatric disorders. Hypermagnesemia is primarily seen in acute and chronic renal failure, and is treated effectively by dialysis.

Evaluation of magnesium before and after jejuno-ileal versus gastric bypass surgery for morbid obesity

Jejuno-ileal bypass surgery for morbid obesity can cause metabolic and electrolyte imbalances. Another case of severe, symptomatic magnesium deficiency after jejuno-ileal bypass surgery is described. This complication was not encountered in a prospective evaluation of the magnesium status after gastric restrictive bypass surgery. Significant (p less than 0.005) body weight decrease was not accompanied by any (serum, erythrocyte or urinary) evidence of magnesium loss for 12 months after surgery.

Magnesium deficiency: pathogenesis, prevalence, and clinical implications

Hypomagnesemia is probably the most underdiagnosed electrolyte deficiency in current medical practice. Patients with cardiovascular disease who are at greatest risk for the development of magnesium deficiency are those treated with diuretics or digitalis. Both potassium and magnesium deficiencies are associated with increased ventricular ectopy and may increase the risk of sudden unexpected death. Refractory potassium repletion can be caused by concomitant magnesium depletion, and can be corrected with magnesium supplementation. Routine serum magnesium determination is recommended whenever the testing of electrolyte levels is required, especially in patients taking diuretic drugs or digitalis. Because hypomagnesemia is not necessarily present in a magnesium-deficient state, it is recommended that both potassium and magnesium be repleted in patients with hypokalemia. Potassium-/magnesium-sparing diuretics may be helpful in the prevention of these electrolyte deficiencies.

Plasma and skeletal muscle electrolytes in patients with Crohn's disease

Plasma and skeletal muscle electrolytes were measured in 13 patients with Crohn's disease, and in an age- and sex-matched reference group. Patients with Crohn's disease demonstrated significantly lower muscle potassium content (p less than 0.01) than did controls. Patients with extensive involvement of the bowel tended to have lower muscle potassium content. The patient population did not differ significantly from the controls with regard to skeletal muscle magnesium content but displayed a far wider range of values. Our results indicate that potassium depletion is present in nonresected patients with Crohn's disease.