FGF23 and vitamin D deficiency: FGF23 promotes excess phosphate excretion into the urine by downregulating the expression of sodium-phosphate cotransporters (NaPi2a/NaPi2c) in the proximal tubules and reduces serum 1,25-dihydroxyvitamin D.3,4 Although chronic alcoholism is known to cause hypophosphatemia and bone fragility through mechanisms that are mainly related to vitamin D deficiency and damage to the renal tubules,5,6 we recently reported 2 alcoholic patients with hypophosphatemic osteomalacia, which was obviously induced by FGF23 oversecretion, and the condition was remedied by abstinence.7