Etiology of Hypophosphatemia Hypophosphatemia has numerous causes but clinically significant acute hypophosphatemia occurs in relatively few clinical settings, including the following: The recovery phase of diabetic ketoacidosis Acute alcohol use disorder Severe burns When receiving total parenteral nutrition (TPN) Refeeding after prolonged undernutrition Severe respiratory alkalosis Acute severe hypophosphatemia with serum phosphate < 1 mg / dL (< 0.32 mmol / L) is most often caused by transcellular shifts of phosphate often superimposed on chronic phosphate depletion.