II. Indications: Hypophosphatemia

  1. Serum Phosphorus < 2 mg/dl
    1. Symptom onset when phosphorus <2 mg/dl
    2. Severe symptoms (Muscle Weakness, Rhabdomyolysis) when Serum Phosphorus <1 mg/dl
  2. Serum Phosphate Replacement is not required in most cases
    1. Hypophosphatemia resolves spontaneously when primary cause is managed
    2. Treat Diabetic Ketoacidosis, Vomiting, Diarrhea, Vitamin D Deficiency and phosphate normalizes

III. Preparations

  1. Oral
    1. K-Phos Tab
      1. Phosphorus: 8 mmol (250 mg)
    2. Neutra-Phos Tab
      1. Phosphorus: 8 mmol (250 mg)
    3. Fleets Phosphosoda
      1. Phosphorus: 4 mmol (128 mg)
  2. IV
    1. Sodium Phosphate
      1. Phosphorus: 3 mmol/ml
      2. Sodium: 4 meq/ml
    2. Potassium Phosphate (K-Phos)
      1. Phosphorus: 3 mmol/ml
      2. Potassium: 4.4 meq/ml

IV. Management: Oral Replacement

  1. Indications
    1. Serum phosphate 1.0 to 1.9 mg/dl
  2. Precautions
    1. Reduce dose to 50% in Chronic Kidney Disease
    2. Recheck serum phosphate 2-12 hours after last dose
  3. Dose: General
    1. Typical adult dose: 250-500 mg (8-16 mmol) orally four times daily for 24 hours, then recheck
  4. Dose: Serum Phosphorus 1.5 to 2.0 mg/dl
    1. Phosphorus 1 mmol/kg (min 40 and max of 80 mmol/day) divided four times daily x1 day
  5. Dose: Serum Phosphorus 1.0 to 1.5 mg/dl
    1. Phosphorus 1.3 mmol/kg (max of 100 mmol/day) divided four times daily x1 day

V. Management: IV Replacement

  1. Indications
    1. Serum phosphate <1.0 mg/dl
    2. Switch to oral replacement when serum phosphate >1.5 mg/dl
  2. Precautions
    1. Avoid doses in excess of 0.24 mmol/kg if possible
    2. Use slower rates of replacement (0.08 to 0.20 mmol/kg) especially if more recent Hypophosphatemia onset
    3. Risk of precipitating calcium, with secondary Hypocalcemia, Acute Renal Failure and arrhythmias
  3. Dose: Serum Phosphorus 1.3 to 2.0 mg/dl
    1. Phosphorus 0.08 to 0.24 mmol/kg (max: 30 mmol) infused over 6 hours
  4. Dose: Serum Phosphorus <1.3 mg/dl
    1. Phosphorus 0.24 to 0.50 mmol/kg (max: 80 mmol) infused over 8 to 12 hours

VI. References

  1. Yu and Stubbs in Goldfarb (2014) Evaluation and treatment of Hypophosphatemia, UpToDate, accessed online 1/24/2014
  2. Medscape Sodium Phosphate
    1. http://reference.medscape.com/drug/sodium-phosphates-iv-999713
  3. Medscape Potassium Phosphate
    1. http://reference.medscape.com/drug/potassium-phosphate-iv-999714

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