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How does sickle cell anemia become worse when oxygen levels are low?

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Health monitoring — human disease The routine monitoring of blood pressure levels is an important part of assessing an individual's health. Blood pressure provides information about the amount of blood in circulation and about heart function and thus is an important indicator of disease.

In sickle cell anemia, the condition worsens when oxygen levels are low because of the unique properties of hemoglobin S (HbS).

Unlike normal hemoglobin, HbS is highly sensitive to oxygen deficiency. When red blood cells release oxygen to body tissues and the internal oxygen concentration drops, HbS molecules begin to stack into filaments that twist into helical rods. These rods then cluster into parallel bundles, which distort the red blood cells, forcing them into a rigid, crescent-like "sickle" shape.12

These misshapen, rigid cells become trapped and clog small blood vessels, obstructing microcirculation and causing tissue damage. While this process is initially reversible upon re-oxygenation, repeated cycles of sickling lead to permanent cellular distortion and the severe, painful crises characteristic of the disease.12