Increased Urinary Phosphate Excretion Induced by Fibroblast Growth Factor 23 in Zinc-deficient Rats

Zinc (Zn) is an essential trace element that is an important nutrient cofactor of numerous enzymes, transcription factors, and an intracellular signaling mediator . Physiological Zn is a cofactor of more than 300 enzymes, and more than 2,000 Zn-dependent proteins involved in stabilizing protein structures. Zn deficiency leads to anorexia, loss of appetite, failure of smell and taste, human growth retardation, and alopecia and osteoporosis in animals. It is important to realize that Zn deficiency is a major worldwide health problem with more than 30% of the global population at risk, predominantly in underdeveloped countries . Of the Zn in the whole body, 90% is contained in muscle and bone. Bone is composed of inorganic mineral hydroxyapatite, which includes calcium (Ca), phosphate (Pi) and Zn. Metabolism of Ca and Pi in bone is strictly regulated by 1,25-(OH)2-vitamin D3 (1,25-VD3) and parathyroid hormone (PTH). Increased PTH secreted from the parathyroid gland leads to an elevated serum Ca level, reduced serum Pi level, but increased urinary excretion of Pi, indicating that the balance of Ca and Pi represents an inverse relationship . Shimada et al. cloned cDNA from a hemangiopericytoma that caused hypophosphatemic osteomalasia and Original Article