Hypophosphatemia
A 74-year-old man with hypertension and gastroesophageal reflux is evaluated for diffuse bone pain and is found to have hypophosphatemia (serum phosphate 1.6 mg/dL). For several years he has taken large daily doses of over-the-counter aluminum hydroxide antacids for reflux. He denies fever, weight loss, myalgias, weakness, or diarrhea, has an excellent appetite, and eats a normal balanced diet. Serum calcium and creatinine are normal, and there is no glucosuria, aminoaciduria, or metabolic acidosis. Which of the following is the most likely cause of his hypophosphatemia?