Hemoglobin S - Pathophysiology
Cells stay biconcave as long as hemoglobin is oxygenated
When
hemoglobin becomes deoxygenated:
Hemoglobin
is less soluble
Sickling
of cells occurs due to tactoids or crystals forming
Viscosity of
blood increases causing:
Red
cells to stay in low oxygen tension longer
pH
of tissue increases causing decreased oxygen
affinity which further increases deoxygenation of hemoglobin
molecule
Hb SS –
sickling begins when oxygen saturation is <85%
Hb S – sickling begins when oxygen saturation is
<40%