Features of iron-dextran changes:
(1) history of recent intravenous infusion of iron-dextran
(2) reddish-brown plasma
(3) negative tests for free plasma hemoglobin
(4) absence of other features seen in hemolysis
(5) high serum iron levels
(6) negative direct Coombs test
Tests for free plasma hemoglobin:
(1) spectrophotometric scanning from 300 to 700 nm (oxyhemoglobin gives a large peak at 415 nm with smaller peaks at 540 and 578 nm, with methemalbumin at 621-625 nm)
(2) Gomori's iron stain (equal parts of 20% hydrochloric acid and 10% potassium ferrocyanide)
(2a) iron dextran: deep blue color
(2b) hemoglobinemia: dark brown, muddy precipitate
Other features of hemolysis:
(1) rise in serum bilirubin and LDH
(2) discolored urine (hemoglobinuria and/or urobilinogen) with hemosiderin
(3) increase in serum potassium
(4) decreased plasma haptoglobin
(5) decrease in hemoglobin and hematocrit
Differential diagnosis:
(1) myoglobinuria
