Why does MCV increase in megaloblastic anemia?
Why does MCV increase in megaloblastic anemia?
In these instances the peripheral blood smear may show a mixed population of microcytic and macrocytic RBCs with an elevated distribution width. In cases of macrocytosis related to alcoholism the elevated MCV may be due to the direct effect of the alcohol, liver disease and/or folate deficiency.
What is MCV in megaloblastic anemia?
Megaloblasts are large nucleated red blood cell (RBC) precursors with noncondensed chromatin due to impaired DNA synthesis. Macrocytes are enlarged RBCs (ie, mean corpuscular volume [MCV] > 100 fL/cell). Macrocytic RBCs occur in a variety of clinical circumstances, many unrelated to megaloblastic maturation.
Is MCV low in microcytic anemia?
Microcytic anemia is defined as the presence of small, often hypochromic, red blood cells in a peripheral blood smear and is usually characterized by a low MCV (less than 83 micron 3). Iron deficiency is the most common cause of microcytic anemia.
Can MCV be normal in megaloblastic anemia?
Megaloblastic Anemia Mean red cell volume (MCV) cannot, however, be used diagnostically to evaluate status—the test has poor specificity and sensitivity and values > 100 fL as a consequence of vitamin B12 insufficiency reflect an advanced deficient state with regards to hematological dysfunction only.
What is the MCV of megaloblastic anemia?
It was observed that MCV was greater than 97 fl in 15 cases of aplastic anemia (mean MCV 109.7 fl), and 25 cases of megaloblastic anaemia (mean MCV 113.2 fl). Hb, MCV & MCHC were comparable in the two groups.
Can a macrocytic anemia be a nonmegaloblastic anemia?
Macrocytic (ie, MCV > 100 fL/cell) anemias due to vitamin B12 deficiency or folate deficiency are megaloblastic. Nonmegaloblastic macrocytosis occurs in various clinical states, not all of which are understood. Anemia can occur in patients with macrocytosis due to mechanisms independent of the macrocytosis.
What is the MCV of normocytic anaemia?
Normocytic anaemias have an MCV of between 80-100 and include anaemia of chronic disease, hereditary spherocytosis, sickle cell anaemia, paroxysmal nocturnal haemoglobinuria, G6PD deficiency, immune haemolytic anaemia, microangiopathic haemolytic anaemia and underproduction of RBCs.
How does vitamin B12 deficiency cause megaloblastic anaemia?
Vitamin B12 deficiency is the less common megaloblastic anaemia as the liver has large hepatic stores of vitamin B12 that take a while to become depleted. 20 Vitamin B12 absorption requires the cofactor known as intrinsic factor, manufactured by gastric parietal cells.
