Causes of Hypophosphatemia

MUSCULOSKELETAL, NEPHROLOGY

Major causes of hypophosphatemia

True Hypophosphatemia happens through 4 major mechanisms:

1. Internal redistribution (Redistribution of phosphate from the extracellular fluid into cells)

  • 2/2 to increased insulin secretion, particularly during refeeding, in refeeding syndrome.
  • Acute respiratory alkalosis
  • Hungry bone syndrome.

2. Decreased intestinal absorption of phosphate

  • From inadequate intake
  • Poor absorption: Inhibition of phosphate absorption caused by antacids, phosphate binders, niacin, etc.
  • Steatorrhea and chronic diarrhea
  • Vitamin D deficiency or resistance to vitamin D

3. Increased urinary phosphate excretion

  • Primary and secondary hyperparathyroidism
  • Vitamin D deficiency or resistance to vitamin D
  • Hereditary hypophosphatemic rickets
  • Oncogenic osteomalacia
  • Fanconi syndrome
    Other – acetazolamide, tenofovir, IV iron, chemotherapeutic agents

4. Removal by renal replacement therapies

Spurious hypophosphatemia can be caused by interference of paraproteins with the phosphate assay.

 

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