Background: Microcytic erythrocytosis is an underrecognized and underevaluated complete blood count (CBC) finding. The literature pertaining to the determination of its etiology specifically by hemoglobin variant analysis is limited.
Methods: We performed hemoglobin variant analysis by high performance liquid chromatography on 137 patients who revealed microcytic erythrocytosis on CBC, and reviewed the results for the diagnosis of hemoglobin-associated disorders.
Results: A diagnosis of thalassemia trait and/or a hemoglobinopathy was established in 93 of 137 (67.9%) patients. Amongst these, ß-thalassemia trait topped the list with 69 cases (74.1%), followed by hereditary persistence of fetal hemoglobin with 5 cases (5.5%), Hemoglobin E disease with 4 cases (4.3%), and ∂/ß-thalassemia with 2 cases (2.1%). Compound heterozygous conditions with 1 or more hemoglobinopathies and/or thalassemias were diagnosed in 13 cases (14.0%). Abnormal hemoglobins in the compound heterozygosity group included C, S, HPFH, and 2 unknowns.
Conclusion: Hemoglobin variant analysis provided a very high positive yield in determining the etiology of microcytic erythrocytosis.