A 50-year-old man presents with feeling tired and unsteady on his feet. He has a poor appetite and has lost 10 lb. On examination, he appears cachectic, his heart and lungs are normal, but his liver span is 18 cm. His lab tests show a very low magnesium level (0.7 mEq/L). On further questioning, he reports drinking heavily since losing his job. Which of the following is the most likely explanation for his low magnesium level?

Magnesium deficiency is most commonly due to alcoholism. Renal loss and malabsorption are also common causes. Magnesium deficiency is not seen in hypervitaminosis E. Causes of magnesium deficiency also include milk diets in infants, the diuretic phase of acute tubular necrosis, chronic diuretic therapy, acute pancreatitis, and inappropriate antidiuretic hormone. The symptoms of hypomagnesemia include anorexia, nausea, tremor, and mood alteration. Symptoms can also be caused by the associated hypocalcemia or hypokalemia.