Hyposplenism and asplenia
Hyposplenism is reduced splenic function and asplenia is absent splenic function; both impair clearance of blood-borne organisms and make rapidly progressive infection, particularly with encapsulated bacteria, a lifelong emergency risk.
Definition
Hyposplenism is reduced splenic function and asplenia is absent splenic function. The cause may be anatomical, such as surgical removal or congenital absence, or functional, such as sickle-cell disease or coeliac disease. The clinical importance is increased susceptibility to rapidly progressive invasive infection and the need for lifelong prevention and emergency planning.
First principles
The spleen filters blood and clears opsonised organisms
The spleen removes abnormal red-cell inclusions and opsonised blood-borne organisms through its red pulp, while marginal-zone B cells and other immune cells support rapid antibody responses to polysaccharide capsules. Loss of these functions explains both Howell–Jolly bodies on the blood film and the increased risk of overwhelming infection.
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