Methemoglobin, Blood

647

1 mL whole blood collected in a sodium heparin (green-top) tube

0.5 mL

EDTA (lavender-top) tube

Please note: Due to the short specimen stability, special logistic arrangements, via FED EX or STAT courier, etc. must be made prior to ordering this test. Packaging for samples going to Chantilly must be labeled with a pink Special Handling sticker, (available through Chantilly Supplies, Item # L115).
Samples received exceeding the 48- hour stability will be rejected

Refrigerated (cold packs)

Room temperature: 1 hour
Refrigerated: 48 hours
Frozen: Unacceptable

Received room temperature

Set up: Daily; Report available: 1 day

0.0-2.9 % of total Hgb

The iron in Hemoglobin is normally maintained in the ferrous state by several effective mechanisms so that only a small percentage of the total hemoglobin is in the form of Methemoglobin. The production of Methemoglobin by oxidation of the iron to the ferric state, renders the hemoglobin incapable of interacting reversibly with molecular oxygen. The oxygen affinity of the unaffected heme is also increased, resulting in the decreased release of oxygen to the tissues at low partial pressure of oxygen.
Methemoglobinemia is usually caused by exposure to various chemical agents, many which contain nitrogen. An increase in Methemoglobin can also occur due to Methemoglobin Reductase Deficiency (Congenital Methemoglobinemia).