1) Decreased urinary excretion

  • Renal failure – Increased retention with reduced GFR
  • Hypoparathyroidism (PTH essential to renal excretion)
    • Primary and Secondary
  • Hyperthyroidism
    • Increased renal retention and bone resorption

2) Increased exogenous load

  • When load exceeds renal capacity to excrete
  • Increased risk in renal failure, bowel mucosal ulceration, ileus
  • Laxatives, enemas

3) Increased endogenous load

  • Tumour lysis syndrome
  • Rhabdomyolysis
  • Severe haemolysis
  • Bowel infarction
  • Malignant hyperthermia
  • Bisphosphonates used in calcium treatment

Clinical manifestations

  • Associated with hypocalcaemia and volume contraction
  • Precipitates calcium out in serum
  • Reduces calcitriol production
  • Decreases calcium absorption form GI tract
  • Tetany and paraesthesia (Compounds HYPOcalcaemia)


Dependant on duration and cause

  1. Acute
    • Volume expansion if no renal failure
    • Dialysis if renal failure or tumour lysis syndrome
    • Insulin and dextrose (Transcellular)
      • Shifts phosphate from extracellular to intracellular
  2. Chronic
    • Phosphate binding agents
    • Protein diet reduction
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