FALSELY DECREASED TOTAL SERUM-CALCIUM CONCENTRATION ASSOCIATED WITH IRON DEXTRAN INJECTION

We cared for a patient in whom iron dextran administration interfered with the determination of total serum calcium concentration. An unexpe cted elevation in serum phosphorus concentration also occurred after t he iron dextran infusion. A MEDLINE search from 1966 to present was co nducted, and the manufacturer of the iron dextran was contacted for in formation related to these findings. Several drugs and diseases were f ound that may decrease serum calcium and increase phosphorus concentra tions. We found one anecdotal citation of iron dextran interfering wit h serum calcium concentrations, but no reports of interference with se rum phosphorus concentrations. Doses of iron dextran in excess of 250 mg may cause a false decrease in total calcium concentration more than 4 hours after the infusion is completed. A false increase in serum ph osphorus concentrations after the infusion requires further investigat ion.