Friday December 16, 2005
Quick bedside test for Methemoglobinemia

A quick bedside test to strongly suspect (MetHb) Methemoglobinemia is to bubble 100% oxygen in tube with patient's dark blood. No change in Color strongly predicts Methemoglobinemia. If blood turns red on exposure to oxygen, cause is probably cardiopulmonary disease. (Same test can be done with 2 drops of patient's blood on white filter paper and exposing it to atmospheric oxygen. Change in color rule out Methemoglobinemia). Although Co-oximetry is an accurate method for measuring Methemoglobinemia, not all machines can (only newer versions can) differentiate it from another rare disorder sulfhemoglobinemia.

References:
1. A case of sulfhemoglobinemia and emergency measurement of sulfhemoglobin with an OSM3 CO-oximeter - Clinical Chemistry 43: 162-166, 1997;
2. Pitfalls in Discriminating Sulfhemoglobin from Methemoglobin - Clinical Chemistry 43: 1098-1099, 1997;
3. Methemoglobinemia - please register free at emedicine.com