mechanisms of hypophosphatemia

Intracellular uptake of phosphate from the extracellular fluidanki

• acute respiratory alkalosis:
  • increased intracellular pH stimulates phosphofructokinase activity and glycolysis which leads to intracellular uptake of phosphate;
  • hyperventilation (caused for example by sepsis, anxiety, diabetic ketoacidosis, or other underlying conditions) can precipitate intracellular shift of phosphate into cells;
• refeeding of malnourished patients;
• administration of insulin or glucose (which stimulates insulin secretion); hungry bone syndrome.

Reduced intestinal phosphate absorption:anki

• inadequate intake is not sufficient to cause hypophosphatemia but contributes to other mechanisms;
• nonabsorbable antacids containing aluminum and magnesium block intestinal absorption of phosphorus;
• vitamin D is required for phosphate absorption; chronic diarrhea can contribute, especially if malabsorption syndromes leads to vitamin D deficiency.

Increased renal excretion due to:anki

• elevated phosphaturic hormones (parathyroid hormone [PTH] or fibroblast growth factor [FGF-23]); common medications including bisphosphonates and denosumab may increase PTH secretion and result in drug-induced hypophosphatemia;
• decreased renal tubular absorptive capacity as a result of:
  • diuretics;
  • Fanconi Syndrome;
  • genetic defects in renal tubule phosphate transporters.