Hyperphosphatemia

Hyperphosphatemia

• Definition: Phosphate >4.5mg/dL (1.45 mmol/L)
• Causes
  • Decreased Renal Excretion (MC)
    • Acute < Chronic Kidney Disease
    • Hypoparathyroidism
  • Transcellular Shift from ICF to ECF
    • Rhabdomyolysis
    • Tumor Lysis Syndrome
    • Massive Hemolysis
    • Metabolic Acidosis
    • Insulin Deficiency (DKA) > Lactic Acidosis
    • Fulminant Hepatitis
    • Severe Hyperthermia
  • Increased Intake
    • Vitamin D analog use
    • Bisphosphonates
    • Fosphenytoin
    • Phospho-soda Enemas (Fleet)
  • Pseudo
    • Hyperbilirubinemia
    • Hyperlipidemia
    • Hemodialysis
    • Hemolyzed sample
    • Liposomal Amphotericin B
    • Paraproteinemia (multiple myeloma)
  • Increased Reabsorption
    • Tumoral Calcinosis (FGF23 defect)
• Symptoms
  • Asymptomatic
    • Related to hypocalcemia
    • Binds calcium and precipitates it in the tissue
  • Metastatic calcifications may occur
    • Painful nodules, calcification of soft tissues, pruritis
  • Calciphylaxis
• Complications
  • Renal Osteodystrophy
  • Phosphate nephropathy
• W/U: Calcium-Phosphate Product
  • Predicts risk of calciphylaxis (>70 causes a risk of calciphylaxis)
• Treatment
  • Should correct within 12-24hr if normal kidney function
  • Acute
    • Phosphate restricted diet
    • Stop VitD
    • Increase Renal Excretion
    • Normal Saline (IVF) and Acetazolamide +/- Lasix
    • Hemodialysis
      • Increase frequency or duration
  • Renal Failure
    • Phosphate restricted diet + oral phosphate binders
    • Sevelamer (Renagel)
      • 800mg TID w/meals, double dose PRN
      • Check med interactions (may absorb some drugs)
      • Preferable in dialysis, avoids mg/ca problems
    • Calcium acetate (PhosLo)
      • 667mg (two tablets TID w/meals)
      • Pts with significant hypocalcemia and Ca-phos product <70
      • Avoid in hypercalcemia, product >66, vitD intoxication
    • Lanthanum
    • Calcium carbonate