Overview

• The amount of hemoglobin (Hb) in a stated volume is a measure of the oxygen-carrying ability of erythrocytes.
• Associated with packed cell volume (PCV) Hematology: packed cell volume.

Sampling

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.

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.

Availability

• Widely available at commercial laboratories.

Validity

Sensitivity

• Good.

Specificity

• High.

Predictive value

• Good.

Technique (intrinsic) limitations

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

Technician (extrinsic) limitations

• Results needs to be repeatable.
• Technical skill required.

Result Data

Further Reading

Publications

Refereed papers

• Recent references from VetMedResource and PubMed.

Other sources of information

• Cowell R J, Tyler R D & Meinkoth J H (1999) Diagnostic Cytology and Hematology of the Dog and Cat. 2nd edn. Mosby, USA.
• Duncan J R, Prasse K W & Mahaffey E A (1994) Veterinary Laboratory Medicine Clinical Pathology. 3rd edn. Iowa University Press, USA.
• Jain N C (1993) Essentials of Veterinary Hematology. Lea & Febiger, USA.