Determination of etiology in patients admitted due to isolated leukopenia

Patients with isolated leukopenia pose difficulties in diagnosis because there is no related guideline in the literature. In this study, our aim was to evaluate the clinical and laboratory associations of isolated, nonspecific (not related to neutropenia) leukopenia. In this retrospective data review study, patients who were admitted to Hacettepe University Hematology Outpatient Clinic between 2014 and 2019 due to leukopenia were evaluated. The patients with anemia (other than iron deficiency) or thrombocytopenia were excluded. Clinical and laboratory data and the final diagnoses (if present) of the remaining cases and especially of those without neutropenia (the most difficult group to diagnose) were evaluated. One hundred sixty-nine patients were included in the study. One hundred forty-four (85.2%) patients were female and 25 (14.8%) were male. One hundred ten of them had 1500/µL or higher neutrophil count. In these nonneutropenic cases, the etiological factors contributing to leukopenia were as follows: iron deficiency anemia (21.8%), other autoimmune/autoinflammatory diseases (17.3%), autoimmune thyroid disease (21.8%), autoimmune laboratory tests (2.7%), drugs (12.7%), infection (5.5%), hematopoietic disorder (2.7%), hypersplenism (2.7%), radiotherapy sequel (1.8%), and B12 deficiency (1.8%). No etiology was recognized in 44 patients. On the other hand, the etiological factors in patients with neutrophil count <1500/µL were as follows; iron deficiency anemia (10.2%), other autoimmune/autoinflammatory diseases (17%), autoimmune thyroid disease (5.1%), autoimmune laboratory tests (8.5%), drugs (8.5%), infection (6.8%), hematopoietic disorder (11.9%), hypersplenism (1.7%), radiotherapy sequel (1.7%), and B12 deficiency (1.7%). No etiology was recognized in 25 patients. Physicians ordered bone marrow examination more frequently in patients with neutropenia. If isolated antinuclear antibody positivity was also considered in favor of autoimmunity, 91/169 (53.8%) cases had an autoimmune diagnosis or laboratory finding. In the present study, the most frequent reasons of isolated leukopenia in nonneutropenic patients are found as iron deficiency anemia, other autoimmune/autoinflammatory diseases, and autoimmune thyroid disease. In neutropenic patients, the most frequent reasons of isolated leukopenia are found as iron deficiency anemia, autoimmune/autoinflammatory diseases, and hematopoietic disorders. Therefore, autoimmunity is detected as an important factor leading to isolated leukopenia.