5th April 2024

Hypophosphatemia

The three main ways significant hypophosphatemia (< 0.4 mmol/L) may result include inadequate intake; renal losses or through redistribution into cells.

• Inadequate intake:
  • Secondary to poor diet, eating disorders such as anorexia nervosa and alcohol dependency 
  • Malabsorption or recurrent vomiting 
  • Vitamin D deficiency
  • Use of phosphate binders such as aluminium hydroxide
• Renal losses:
  • Hyperparathyroidism – PTH reduces reabsorption at the proximal renal tubules
  • Renal tubular disorders – Fanconi’s syndrome and Dent’s disease
  • Vitamin D deficiency – including hypophosphatemic rickets
  • Drugs – aminoglycoside, cisplatin and tenofovir cause renal phosphate leak
  • Post renal transplantation – low phosphate is common, especially after a prolonged period of dialysis
  • Paraproteinemias and heavy metal poisoning that impair renal tubule function
  • Oncogenic osteomalacia 
• Redistribution:
  • Treating diabetic ketoacidosis – insulin drives phosphate into cells
  • Refeeding syndrome 
  • Acute respiratory alkalosis 
  • Hungry bone syndrome post parathyroidectomy
  • Lymphomas or leukaemia