LYM

A low percentage can reflect increased neutrophils during bacterial infection, inflammation, obesity, physical stress, or corticosteroid use, even with a normal absolute lymphocyte count. Interpret alongside LYMabs and the rest of the white cell differential.

Current cigarette smoking can lower LYM% by disproportionately increasing neutrophils, even when the absolute lymphocyte count is normal or elevated.

Recent viral illness, recovery after strenuous exercise, corticosteroids, and other immunosuppressants can also lower the absolute lymphocyte count.

Protein-energy malnutrition and zinc deficiency can contribute when the absolute lymphocyte count is also low.

Persistent absolute lymphopenia can accompany HIV, autoimmune disease such as lupus, lymphoma, or inherited immune disorders.

Correct inadequate protein and calorie intake when malnutrition contributes to a low absolute lymphocyte count.

A high percentage can reflect fewer neutrophils rather than excess lymphocytes. Common benign examples are the Duffy-null variant (benign ethnic neutropenia), more common in people of African, Middle Eastern, or West Indian ancestry, and the lower neutrophil counts seen with endurance training. Interpret alongside LYMabs and the absolute neutrophil count; percentage alone does not establish absolute lymphocytosis.

Viral infections, especially Epstein-Barr virus or cytomegalovirus, can cause a reactive increase. Pertussis is another cause.

Drug hypersensitivity reactions can cause a reactive increase in lymphocytes.

Lymphocyte counts can remain elevated after removal of the spleen.

Conditions such as chronic lymphocytic leukemia can cause persistent lymphocytosis. Persistent unexplained elevation, particularly with a high absolute count, deserves further assessment.