Wine-Colored Plasma and Urine from Hydroxocobalamin Treatment

Abstract

A 49-year-old male was admitted following a house fire that resulted in burns to 20 % of his total body surface area. Empiric hydroxocobalamin was given for presumed cyanide poisoning secondary to smoke inhalation. Plasma and urine from the patient were noted to have an intense dark red/purple hue (Fig. 1).Approximately 35 % of fire victims experience toxicity from cyanide, generated during pyrolysis of such synthetic materials as plastics, rugs, silks, and furniture. Cyanide inhibits cytochrome oxidase in the electron transport chain and blocks aerobic metabolism, causing a histotoxic hypoxia. Hydroxocobalamin chelates cyanide and forms the nontoxic, renally excreted cyanocobalamin. A common side effect of hydroxocobalamin is a stunning dark red/purple discoloration of the recipient's skin, mucosal membranes, and body fluids, including plasma and urine. Although the pigmentation is harmless and resolves spontaneously within days, it can cause analytical interference with a number of common chemistry, hematology, and coagulation tests.2 The clinical significance of these transient alterations remains to be determined. More concerning is the increase in carboxyhemoglobin and methemoglobin and decrease in oxyhemoglobin from hydroxocobalamin interference observed with certain co-oximeters.3 As smoke inhalation victims often demonstrate concomitant carbon monoxide and cyanide toxicities, initial blood gas measurements should be obtained prior to hydroxocobalamin administration. Our patient had a carboxyhemoglobin level of 20.5 % (normal, < 2.5 %) before hydroxocobalamin treatment, thereby confirming concurrent carbon monoxide poisoning.

Transfusion confusion: hemolysis or eltrombopag?

“…Furthermore, such samples can show analytical interference with some spectrophotometric assays, depending on the instrument, methodology and reagents used to measure the analyte (e.g., total bilirubin) . Some additional examples of medications that can cause plasma discoloration which may get confused with hemolysis or make visual hemolysis check challenging include iron dextran, hydroxocobalamin, atovaquone, and hemoglobin‐based oxygen carriers such as PEGylated carboxyhemoglobin bovine (SANGUINATE™) and HBOC‐201 (Hemopure™) . It is important that clinical laboratories and clinicians be aware of these effects given the potential impact on clinical decision making and care.…”