Hyperphosphatemia Hypophosphatemia
Reduced renal phosphate excretion. eg
  • Later stages of CKD
  • Variants of Tumoral Calcinosis
  • Biphosphate therapy
  • Metabolic alkalosis
Increased urinary excretion of phosphate. eg
  • Tumor Induced osteomalacia
  • Autosomal Dominant hypophosphatemic rickets
  • X-linked hypophosphatemic rickets
Efflux of intracellular phosphate. eg
  • Tumor lysis syndrome
  • Catabolic states
  • Chronic respiratory alkalosis
  • Increased dopamine and adrenergic activity
Internal redistribution. eg
  • Refeeding in malnourished patients
  • Increased intracellular pH
  • Hungry bone syndrome
Increased Dietary phosphate Decreased dietary intake of phosphate (Rare)
Table 3: Mechanism of hyper- and hypo-phosphatemia.