Evaluation of Macrocytosis in Routine Hemograms

Abstract

Macrocytosis, a condition in which erythrocytes are larger than normal manifests as an increase in mean corpuscular volume (MCV) more than 100 fl. The aim of this study was to identify the underlying causes of macrocytosis, detected in routine hemograms and to evaluate the hematological features in different etiologies. This study included 178 adult patients whose detailed medical history was recorded, and Vitamin B12 assay, folate assay, thyroid function tests, liver function tests, complete blood counts and peripheral smear evaluation was performed. Alcoholism was identified as the etiological factor in 65 cases (36.5%), Vitamin B12 deficiency in 43 cases (24.1%) and drug related in 23 cases (12.9%). These three conditions accounted for 73.6% of macrocytosis. Other causes identified were folate deficiency, liver disease, Myelodysplastic syndrome, chronic renal failure and Aplastic anemia. In 41 cases, the cause of macrocytosis could not be explained. Anemia was observed in 95 cases (53.3%) being most common in Vitamin B12 deficiency. 9 cases (20.9%) of Vitamin B12 deficiency presented with isolated macrocytosis without anemia. It was observed that mean hemoglobin was lower and red cell distribution width (RDW) higher in megaloblastic conditions. Peripheral smear revealed hypersegmented neutrophils in 86% and macroovalocytes in 72% of the megaloblastic cases. Complete medical history, red cell parameters and peripheral blood smear are simple, inexpensive tools which assist in identifying the underlying cause of macrocytosis, particularly in resource limited settings. Macrocytosis needs to be evaluated even in the absence of anemia, as it may be the first clue to an underlying pathology.

Could an analysis of mean corpuscular volume help to improve risk stratification in non-anemic patients with acute myocardial infarction?

“…Megaloblastic process is caused by impaired DNA synthesis that may be linked to certain drug administration (e.g. metformin, methotrexate, trimethoprim, nitrous oxide), folate or vitamin B 12 deficiency [18,19], for instance due to their insufficient supply in food [20,21]. Non-megaloblastic macrocytes occur when a damaging factor acts after a completed erythropoiesis.…”

“…Then, it can be caused e.g. by an increased deposition of lipids on the cell membranes in the course of hepatobiliary diseases [19]. Other causes of non-megaloblastic macrocytosis in patients without anemia could be alcoholism [22] or familial macrocytosis [19].…”

“…by an increased deposition of lipids on the cell membranes in the course of hepatobiliary diseases [19]. Other causes of non-megaloblastic macrocytosis in patients without anemia could be alcoholism [22] or familial macrocytosis [19]. The identification of high MCV does not allow to distinguish these two types of macrocytosis, and we need to acknowledge that the causes of high MCV found in almost 40% of non-anemic patients admitted due to AMI have not been investigated in our study, which might be considered as a study limitation.…”

Causes of macrocytic anemia among 628 patients: mean corpuscular volumes of 114 and 130 fL as critical markers for categorization

“…However, although several studies on macrocytosis have been published, mostly from general internal medicine clinics [6][7][8][9][10][11][12][13][14][15][16], there have been no studies on the distribution of causal diseases of macrocytic anemia according to MCV cutoff values, which would require a large series of patients. Similarly, there have been no studies restricted to macrocytic anemia.…”

“…Similarly, there have been no studies restricted to macrocytic anemia. The most frequent causes of macrocytosis varied from report to report, and included medications [7,13], megaloblastic anemia [8], and alcoholism [9,16], perhaps depending on the clinical setting. Although the MCV value over which megaloblastic anemia is highly likely was described as 110 [2], 115 [3,14] or 120 fL [13], the percent megaloblastic anemia according to MCV cutoff values has not been determined.…”