Approach to phosphate repletion in adults with hypophosphatemia

* Hypophosphatemia in adults is typically defined as a serum phosphorus level less than 2.5 mg/dL (0.81 mmol/L).

¶ In patients with hypophosphatemia, the underlying cause for hypophosphatemia should be addressed.

Δ Phosphate repletion can be stopped when the serum phosphate is greater than or equal to 2 mg/dL (0.64 mmol/L) unless there is an indication for chronic therapy such as persistent urinary phosphate wasting.

◊ Symptoms of hypophosphatemia rarely occur unless the phosphate concentration is less than 2 mg/dL (0.64 mmol/L).

§ Oral phosphate supplements contain varying ratios of sodium and potassium phosphate. To prevent serious medication errors, preparations should be selected with consideration of potassium and sodium content and dosed according to mmol of phosphate. Commonly used potassium phosphate-sodium phosphate supplements contain 250 mg (8 mmol) of phosphorus per tablet or packet. Skim milk may also be used for oral phosphate repletion (approximately 15 mmol/480 mL serving). Patients with kidney function impairment should receive approximately one-half of the suggested initial dose.

¥ Intravenous phosphate is available as potassium phosphate or sodium phosphate; serum potassium levels may guide product selection. Potassium phosphate provides approximately 1.5 mEq of potassium for each 1 mmol of phosphate. To prevent medication errors, dose should be expressed as mmol of phosphate, and sodium or potassium salt should be specified.