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Test Code MET Methemoglobin

Important Note

Specimens cannot be collected by capillary methods.

Additional Codes

Cerner

NextGen

Methemoglobin

Methemoglobin

Alternate Name(s)

Met Hgb

Useful For

Indicates methemoglobinemia, Hb with oxidized (ferric state, Fe3+) heme iron, which does not bind oxygen.

Methodology

Spectrometry

Patient Preparation

None

Collection Instructions

  • Standard phlebotomy practices.
  • Arterial Blood Gas specimens drawn in plastic syringes should not be iced, they should be kept at room temperature and analyzed within 30 minutes of collection (Per NCCLS C46-A, Vol. 21 No.14, Sect 4.2.1.).
  • Place venous specimens on ice and immediately transport to laboratory immediately.Specimen container must be full so that it has the correct heparin/blood ratio.

Specimen Requirements

Minimum Volume

150 µL

Container

Heparinized Syringe free of air bubbles

Or

Lithium Heparin tube

Stability

Room temperature or place on ice immediately for transport and analyze within 30 minutes of collection time.

Rejection Criteria

The Laboratory will not accept specimens in syringes with needles -- the syringe must be capped with a rubber stopper. 

Capillary specimen.

Result Reporting and Reference Values

Reference Range

0-1.5%

Critical Ranges

>35%

Reflex Testing

None

Limitations

  • Air bubbles must be removed from the sample immediately.  Contamination with room air will affect results.
  • Clotting and dilutional effects may be present if the sample collection technique is not performed correctly.
  • The presence of unknown interfering substances, clots or other foreign matter within the blood sample that alters the optical spectrum will result in higher levels of residual spectrum. A sample with an absorbance error will not be reported.
  • The substances listed below showed an interference with CO-Oximetry/tBili analytes causing a clinically significant error (> TEa).