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.
< 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.
Specialty: Endocrinology, Clinical Laboratory, Nephrology