Orientation diagnostique devant une lymphopénie

Lymphopenia is defined as a peripheral lymphocyte count lower than 1500/mm(3) in adults and 4500/mm(3) in children younger than eight months of age. We propose a classification of lymphopenia: • lymphocyte production defects, including primary immune deficiencies and immune deficiencies secondary to malnutrition or zinc deprivation; • excess catabolism, due to causes including radiotherapy, chemotherapy, immunosuppressive therapy, HIV infection, and systemic lupus erythematosus; • abnormal lymphocyte trapping, including mainly splenomegaly, certain viral infections, septic shock, extended burns, systemic granulomatosis, and corticosteroids; • other causes of lymphocytopenia, with mechanisms that remain poorly understood: ethnicity (Ethiopians), lymphoma, renal insufficiency, and idiopathic CD4 lymphocytopenia.