The catch in complete blood count when vitamin B12 deficiency is hiding behind microcytic anemia

Abstract

Abstract Background Insufficient stores of vitamin B12 in human body are thought to result in macrocytic anemia. However, anemia in most of the patients is multifactorial. This is commonly owing to mixed nutritional deficiencies or bowel disorders affecting absorption of more than one element. Resultantly, a single causative agent of anemia like vitamin B12 deficiency may take macrocytic, normocytic, or microcytic forms. Patients presenting with microcytic anemia may have underlying insufficiency of this vitamin in some instances. Assessment of complete blood count (CBC) parameters may be helpful to identify such cases. Methods This study was conducted on 155 patients of microcytic anemia. Assessment of complete blood count (CBC) parameters and vitamin B12 was done using state of the art analyzers. The overall data was analyzed using SPSS version 23. Results Subnormal vitamin B12 levels were found in 17.4% of the studied cases. CBC parameters showed distinct changes in this group. Mean hemoglobin and red blood cell values were lower compared to the subjects having normal B12 values, and mean corpuscular volume and mean corpuscular hemoglobin concentration had an upward trend in cases of severe deficiency. Features of leucopenia and pancytopenia were more frequent also. Macrocytic red blood cells on peripheral smear were useful to detect the hidden deficiency even when the predominant picture consisted of microcytic cells. Conclusions Vitamin B12 deficiency maybe underlying in microcytic anemia patients. Important clues in CBC include very low hemoglobin but mildly decreased MCV values in the presence of leucopenia and macrocytic RBCs on peripheral smear.