Phosphate Imbalances: Causes and Manifestations

Phosphate

• Primary anion in ICF
  • Essential to function of muscle, red blood cells, and nervous system
  • Involved in acid-base buffering system, ATP production, cellular uptake of glucose, and metabolism of carbohydrates, proteins, and fats
  • Serum levels controlled by parathyroid hormone
  • Maintenance requires adequate renal functioning
  • Reciprocal relationship with calcium
• Hyperphosphatemia
  • High serum PO43- caused by
    • Acute kidney injury or chronic kidney disease
    • Chemotherapy
    • Excess intake of phosphate or vitamin D
    • Hypoparathyroidism
  • Manifestations
    • Neuromuscular irritability and tetany (hypocalcemia)
    • Calcified deposits in soft tissue like, arteries, skin, kidneys, and corneas (can cause organ dysfunction)
    • Numbness and tingling in extremities and region around mouth
    • Hyperreflexia, muscle cramps
    • Tetany, seizures
  • Management
    • Identify and treat underlying cause
    • Restrict foods and fluids containing phosphorus
    • Oral phosphate-binding agents
    • Volume expansion and forced diuresis
    • Correct any hypocalcemia
    • Hemodialysis
• Hypophosphatemia
  • Low serum PO₄^3- caused by
    • Malnourishment/malabsorption/diarrhea
    • Use of phosphate-binding antacids
    • Inadequate replacement during parenteral nutrition
  • Manifestations
    • CNS depression
    • Muscle weakness and pain
    • Respiratory and heart failure
    • Rickets and osteomalacia
    • Cardiac problems (dysrhythmias, heart failure)
    • Osteomalacia, rickets
    • Rhabdomyolysis
  • Management
    • Oral supplementation
    • Ingestion of foods high in phosphorus
    • IV administration of sodium or potassium phosphate