Critical Care Medicine-Renal, Electrolyte and Acid Base Disorders>>>>>Calcium, Phosphate, and Magnesium
Question 3#

A 65-year-old male nursing home resident with a history of quadriplegia is admitted to the ICU for respiratory failure. He is intubated and sedated. Tube feeds are initiated. Electrolyte levels are as follows:

• Serum calcium—7.0 mg/dL
• Serum phosphorus—0.9 mg/dL
• Serum magnesium—1.6 mg/dL
• Serum potassium—3.6 mg/dL
• Serum sodium—138 mg/dL

What replacement strategy should be initiated for this patient?

A. IV Calcium followed IV Phosphorus
B. IV phosphorus followed by IV calcium
C. IV calcium followed by oral phosphorus replacement
D. Oral phosphorus replacement only

Correct Answer is A

Comment:

Correct Answer: A

This patient has hypophosphatemia from refeeding syndrome. This patient has concomitant low serum calcium levels. Early replacement of phosphorus is warranted in refeeding syndrome; however, hypocalcemia can worsen with phosphorus replacement; therefore, calcium should be replaced before phosphorus correction.

It is recommended to replace phosphorus with IV supplementation instead of oral due to absorption issues often encountered in this patient group (choice C).

Reference:

1. Mehanna HM, Moledina J, Travis J. Refeeding syndrome: what it is, and how to prevent and treat it. BMJ. 2008;336:1495.