Hemoglobin Testing and Physiology Notes

Hemoglobin Levels and Clinical Testing

• Elevated Hemoglobin Levels:

  • Dehydration

  • Polycythemia

  • Splenic contracture

• Decreased Hemoglobin Levels:

  • Anemia

Hemoglobin Structure and Synthesis

• Functional Role:

  • The protein molecule hemoglobin is the functional unit of the erythrocyte.

• Structural Components:

  • Heme Portion: The iron-containing component of the molecule.

  • Globin Portion: Composed of paired chains of amino acids.

• Synthesis Process:

  • The synthesis of hemoglobin takes place during the maturation of red blood cells (RBCs) in the bone marrow.

Forms of Hemoglobin and Gas Transport

• Circulating Hemoglobin:

  • Multiple different forms of hemoglobin can exist once the molecule enters circulation.

• Oxyhemoglobin:

  • Refers specifically to hemoglobin that is bound to oxygen.

• Gas Exchange During Respiration:

  • When RBCs deliver oxygen to the body tissues, carbon dioxide binds in place of the oxygen.

  • During respiration, carbon dioxide is replaced again by oxygen.

• Methemoglobin:

  • Occurs naturally both within plasma and inside RBCs.

  • Inefficient with respect to oxygen transport.

  • Capable of being converted into hemoglobin and utilized for oxygen delivery.

  • Has a high affinity alongside hemoglobin.

• Sulfhemoglobin:

  • Results directly from normal RBC aging processes.

  • Inefficient when it comes to oxygen transport.

• Carboxyhemoglobin:

  • Results from exposure to carbon monoxide.