Hyposplenism

Hyposplenism is a condition characterized by reduced splenic function, resulting in impaired clearance of bacteria and aged or abnormal blood cells. It is distinct from asplenia, where the spleen is absent or nonfunctional, and from hypersplenism, where the spleen sequesters blood cells excessively, causing cytopenias despite preserved function. In hyposplenism, the spleen is present but does not work normally.

Causes of hyposplenism can be acquired or congenital. Acquired causes include splenectomy or functional impairment after splenic infarction, trauma, or diseases such as sickle cell disease that lead to progressive loss of splenic function (autosplenectomy). Other associations include autoimmune or inflammatory disorders and certain gastrointestinal conditions such as celiac disease, where splenic white pulp atrophy may occur. Congenital hyposplenism is rare and may be seen with other developmental anomalies.

Clinically, hyposplenism increases susceptibility to infections with encapsulated bacteria, notably Streptococcus pneumoniae, Haemophilus influenzae type b, and Neisseria meningitidis. A peripheral blood smear may show Howell-Jolly bodies or other abnormal red blood cells, reflecting impaired splenic filtration. Splenic function can be assessed by tests such as pitted red blood cell counts and radionuclide imaging (eg, 99mTc-labeled colloid scans) to evaluate splenic uptake, though clinical assessment often relies on history, infection risk, and lab findings.

Management focuses on preventing infections. This includes vaccination against pneumococcus, meningococcus, and Haemophilus influenzae type b, along with annual influenza vaccination; consideration of antibiotic prophylaxis in high-risk individuals or early childhood; and prompt antibiotic treatment for febrile illness. Addressing the underlying condition may improve function in some cases, and education about infection risk is essential.