II. Indications: Hypophosphatemia
-
Serum Phosphorus < 2 mg/dl
- Symptom onset when Phosphorus <2 mg/dl
- Severe symptoms (Muscle Weakness, Rhabdomyolysis) when Serum Phosphorus <1 mg/dl
- Serum Phosphate Replacement is not required in most cases
- Hypophosphatemia resolves spontaneously when primary cause is managed
- Treat Diabetic Ketoacidosis, Vomiting, Diarrhea, Vitamin D Deficiency and phosphate normalizes
III. Preparations
- Oral Preparations
- K-Phos Tab
- Phosphorus: 8 mmol (250 mg)
- Neutra-Phos Tab
- Phosphorus: 8 mmol (250 mg)
- Fleets Phosphosoda
- Phosphorus: 4 mmol (128 mg)
- K-Phos Tab
- IV Preparations
- Sodium phosphate
- Phosphorus: 3 mmol/ml
- Sodium: 4 meq/ml
- Potassium Phosphate (K-Phos)
- Phosphorus: 3 mmol/ml
- Potassium: 4.4 meq/ml
- Sodium phosphate
IV. Management: Oral Replacement
- Indications
- Serum Phosphate 1.0 to 1.9 mg/dl
- Precautions
- Reduce dose to 50% in Chronic Kidney Disease
- Recheck Serum Phosphate 2-12 hours after last dose
- Dose: General
- Typical adult dose: 250-500 mg (8-16 mmol) orally four times daily for 24 hours, then recheck
- Dose: Serum Phosphorus 1.5 to 2.0 mg/dl
- Phosphorus 1 mmol/kg (min 40 and max of 80 mmol/day) divided four times daily x1 day
- Dose: Serum Phosphorus 1.0 to 1.5 mg/dl
- Phosphorus 1.3 mmol/kg (max of 100 mmol/day) divided four times daily x1 day
V. Management: IV Replacement
- Indications
- Serum Phosphate <1.0 mg/dl
- Switch to oral replacement when Serum Phosphate >1.5 mg/dl
- Precautions
- Avoid doses in excess of 0.24 mmol/kg if possible
- Use slower rates of replacement (0.08 to 0.20 mmol/kg) especially if more recent Hypophosphatemia onset
- Risk of precipitating Calcium, with secondary Hypocalcemia, Acute Renal Failure and Arrhythmias
- Replacement Solution
- Potassium Phosphate if Serum Potassium is also low
- Sodium phosphate if Serum Potassium is normal or high
- Replacement rate
- Typical replacement rate: 15 mmol/hour
- Dose: Serum Phosphorus 1.3 to 2.0 mg/dl
- Phosphorus 0.08 to 0.24 mmol/kg (max: 30 mmol) infused over 6 hours
- Dose: Serum Phosphorus <1.3 mg/dl
- Phosphorus 0.24 to 0.50 mmol/kg (max: 80 mmol) infused over 8 to 12 hours
VI. References
- Hayes and Swaminathan in Herbert (2021) EM:Rap 21(5): 7-9
- Yu and Stubbs in Goldfarb (2014) Evaluation and treatment of Hypophosphatemia, UpToDate, accessed online 1/24/2014
- Medscape Sodium phosphate
- Medscape Potassium Phosphate