Rosen et al used a protocol for intravenous phosphate repletion in critically ill patients with moderate hypophosphatemia. The authors are from the University of Maryland Medical System in Baltimore.


Patient selection: adult with serum inorganic phosphorus < 2 mg/dL



(1) pregnancy or nursing mothers

(2) hypocalcemia (corrected for albumin < 7.5 mg/dL) or hypercalcemia (corrected for albumin > 11 mg/dL)

(3) creatinine clearance < 10 mL per minute

(4) urine output < 30 mL per hour for the 2 hours prior to initiating the infusion

(5) renal insufficiency with BUN > 80 mg/dL or serum creatinine > 4 mg/dL

(6) condition associated with excess phosphaturia



(1) Infuse 15 mmol of phosphate salt in 100 mL of 0.9% normal saline over 2 hours (infuse at 0.83 mL per minute).

(2) The selection of the phosphate cation is based on the serum potassium level.


Serum Potassium

Phosphorus Cation

< 3.5 mmol/L


>= 3.5 mmol/L



(3) If the serum inorganic phosphorus is still < 2.0 mg/dL at followup (at 6 hours and at 18-24 hour after the initial infusion) then a repeat infusion is administered.

(4) The maximum 24 hour infusion is 45 mmol phosphate salt.



• The correction of the serum calcium for a low serum albumin is discussed earlier in the chapter. One equation is: approximate total serum calcium with normal albumin, in mg/dL = (current total serum calcium in mg/dL) + (0.8 * (4 - (albumin in g/dL)))


Criteria for discontinuation of protocol:

(1) increase in serum inorganic phosphorus concentration > 6 mg/dL

(2) serum phosphorus * calcium product > 60 ((mg/dL)^2)

(3) a drop in the serum calcium by >= 1 mg/dL

(4) a decrease in urine output to < 30 mL per hour

(5) evidence of hyperreflexia



• All patients involved in the study were successfully repleted without serious adverse effects.


To read more or access our algorithms and calculators, please log in or register.