Felis ISSN 2398-2950

Hematology: hemoglobin concentration

Synonym(s): Hb, erythrocyte, RBC, red blood cell

Contributor(s): Karen L Gerber

Overview

  • The amount of hemoglobin (Hb) in a stated volume is a measure of the oxygen-carrying ability of erythrocytes.

Sampling

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Tests

Methodologies

Cyanomethemoglobin

  • Ferricyanide converts hemoglobin iron from the ferrous to the ferric state to form methemoglobin which combines with potassium cyanide to form the stable pigment cyanomethemoglobin.
  • Error 1-2% in automated systems and 2-5% in manual methods.
  • Measures all forms of Hb likely to be in blood.
  • This is probably the most accurate and widely used technique, for determining hemoglobin concentration. It has limitations in routine practice.

Oxyhemoglobin

  • Uses Spencer Hb meter to measure oxyhemoglobin by its light absorption in the green portion of the spectrum using a filter and matching the color with a colored glass standard.
  • Practical, quick and accurate (+/- 5-10%).
    Does not measure methemoglobin and carboxyhemoglobin.

Other methods

  • Acid hematin and direct matching are outmoded and unsatisfactory.

Validity

Sensitivity

  • Good.

Specificity

  • High.

Predictive value

  • Good.

Technique (intrinsic) limitations

  • These techniques do not differentiate between different types of Hb.

Technician (extrinsic) limitations

  • Repeatable.
  • Technical skill required.

Result Data

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Further Reading

Publications

Refereed papers


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