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Methemoglobin, Blood
Test Code647
CPT Codes
83050
Preferred Specimen
1 mL whole blood collected in a sodium heparin (green-top) tube
Minimum Volume
0.5 mL
Other Acceptable Specimens
EDTA (lavender-top) tube
Instructions
Please note: Due to the 48 hour stability, specimens must only be collected and shipped Mon-Thurs (refrigerate sample until transport).
Note: If there is elevated clinical urgency related to collection and submission outside of Mon-Thurs, samples should be collected with commensurate notice provided to the performing laboratory ahead of sample arrival.
For all specimen submissions, 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.
Transport Temperature
Refrigerated (cold packs)
Specimen Stability
Room temperature: 1 hour
Refrigerated: 48 hours
Frozen: Unacceptable
Refrigerated: 48 hours
Frozen: Unacceptable
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Received room temperature
Methodology
Spectrophotometry (SP)
Setup Schedule
Set up: Daily; Report available: 1 day
Reference Range
0.0-2.9 % of total Hgb
Clinical Significance
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).
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).