ABSTRACT
Both hyper-and hypophosphatemia can be caused by transcellular shifts in phosphate. Such shifts can be responsible for wide fluctuations in serum phosphate concentrations, up to 11 mg/dl (3.55 mmol/1) and down to <1 mg/ dl (0.323 mmol/1). In fact, such shifts in phosphate are the most common etiology of hypophosphatemia in the hospitalized patient.1 Although serum phosphate concentration is regulated by dietary intake of phosphate, renal handling of phosphate, and the vitamin D/PTH (parathyroid hormone) system, it is important to consider that marked fluctuations can also occur by shift of phosphate from cells into the extracellular environment and from the intravascular space into cells.
