-
FP Essentials Jul 2023Macrocytic anemia is divided into megaloblastic and nonmegaloblastic causes, with the former being more common. Megaloblastic anemia results from impaired DNA synthesis,...
Macrocytic anemia is divided into megaloblastic and nonmegaloblastic causes, with the former being more common. Megaloblastic anemia results from impaired DNA synthesis, leading to release of megaloblasts, which are large nucleated red blood cell precursors with chromatin that is not condensed. Vitamin B12 deficiency is the most common cause for megaloblastic anemia, although folate deficiency also can contribute. Nonmegaloblastic anemia entails normal DNA synthesis and typically is caused by chronic liver dysfunction, hypothyroidism, alcohol use disorder, or myelodysplastic disorders. Macrocytosis also can result from release of reticulocytes in the normal physiologic response to acute anemia. Management of macrocytic anemia is specific to the etiology identified through testing and patient evaluation.
Topics: Humans; Anemia, Macrocytic; Anemia; Anemia, Megaloblastic; Alcoholism; DNA
PubMed: 37390397
DOI: No ID Found -
American Family Physician Jan 1996In approximately 2 to 4 percent of patients, laboratory evidence of macrocytosis is found. Macrocytic anemias are classified as those resulting from disorders of DNA... (Review)
Review
In approximately 2 to 4 percent of patients, laboratory evidence of macrocytosis is found. Macrocytic anemias are classified as those resulting from disorders of DNA synthesis of erythrocyte precursors in bone marrow (megaloblastic anemias) or those caused primarily by alcoholism, liver disease and hypothyroidism (nonmegaloblastic anemias). A blood smear should be performed to differentiate the two forms. Neutrophil hypersegmentation is one of the most sensitive and specific signs of megaloblastic anemia. Other testing should include vitamin B12 and red blood cell folate levels, reticulocyte count, and thyroid and liver function tests. The Schilling test can determine if B12 can be absorbed and, if not, whether adding intrinsic factor corrects the malabsorption. The most common form of nonmegaloblastic macrocytic anemia results from alcoholism. Nonmegaloblastic macrocytic anemias may be accompanied by increased reticulocyte counts (hemolysis, hemorrhage) or by normal or decreased reticulocyte counts (alcoholism, liver disease, hypothyroidism and various bone marrow disorders).
Topics: Algorithms; Anemia, Macrocytic; Anemia, Megaloblastic; Diagnosis, Differential; Humans
PubMed: 8546042
DOI: No ID Found -
La Revue Du Praticien Oct 1989Macrocytic and/or megaloblastic anaemias of infants and children are more often due to a defective bone marrow production than to haemolysis. They are mostly related to... (Review)
Review
Macrocytic and/or megaloblastic anaemias of infants and children are more often due to a defective bone marrow production than to haemolysis. They are mostly related to folate and/or cobalamin deficiency or to a disturbance in the metabolism of one of these vitamins (enzyme deficiencies or defect of synthesis of their active forms). More rarely, these anaemias are associated with congenital deficiency of the enzymes involved in pyrimidine or purine biosynthesis. A few cases of thiamine-responsive megaloblastic anaemia have been reported. Some blood diseases may also associated with macrocytic anaemia. Finally, many drugs (antifolic agents, antipurine or antipyrimidine compounds) may induce macrocytic anaemia.
Topics: Anemia, Macrocytic; Anemia, Megaloblastic; Folic Acid; Folic Acid Deficiency; Humans; Infant; Vitamin B 12; Vitamin B 12 Deficiency
PubMed: 2683003
DOI: No ID Found -
Postgraduate Medicine Feb 1979The three most common causes of macrocytosis--vitamin B12 or folate deficiency, liver disease, and reticulocytosis--usually can be differentiated on the basis of red... (Review)
Review
The three most common causes of macrocytosis--vitamin B12 or folate deficiency, liver disease, and reticulocytosis--usually can be differentiated on the basis of red cell indexes and morphologic findings. Bone marrow studies are not indicated. In reticulocytosis, the mean corpuscular volume (MCV) rarely exceeds ll0 cu mu and a reticulocyte count quickly establishes the diagnosis. In liver disease, macrocytosis is also mild and uniform. The RBCs are round. In megaloblastic anemia, the MCV may exceed 150 cu mu. The RBCs vary considerably in size and shape. The macrocytes tend to be oval. Serum vitamin B12 determination remains the best test for unmasking vitamin B12 deficiency. It should be ordered in conjunction with serum and red cell folate determinations in the course of investigating a macrocytic anemia. When vitamin B12 deficiency has been established, a Schilling test or plasma uptake test is indicated to pinpoint the cause.
Topics: Aged; Anemia, Macrocytic; Anemia, Megaloblastic; Anemia, Sideroblastic; Clinical Laboratory Techniques; Erythrocytes; Folic Acid; Humans; Liver Diseases, Alcoholic; Male; Radioisotopes; Schilling Test; Vitamin B 12
PubMed: 368738
DOI: 10.1080/00325481.1979.11715063 -
International Journal of Laboratory... Jun 2013The foundation of laboratory hematologic diagnosis is the complete blood count and review of the peripheral smear. In patients with anemia, the peripheral smear permits... (Review)
Review
The foundation of laboratory hematologic diagnosis is the complete blood count and review of the peripheral smear. In patients with anemia, the peripheral smear permits interpretation of diagnostically significant red blood cell (RBC) findings. These include assessment of RBC shape, size, color, inclusions, and arrangement. Abnormalities of RBC shape and other RBC features can provide key information in establishing a differential diagnosis. In patients with microcytic anemia, RBC morphology can increase or decrease the diagnostic likelihood of thalassemia. In normocytic anemias, morphology can assist in differentiating among blood loss, marrow failure, and hemolysis-and in hemolysis, RBC findings can suggest specific etiologies. In macrocytic anemias, RBC morphology can help guide the diagnostic considerations to either megaloblastic or nonmegaloblastic causes. Like all laboratory tests, RBC morphologies must be interpreted with caution, particularly in infants and children. When used properly, RBC morphology can be a key tool for laboratory hematology professionals to recommend appropriate clinical and laboratory follow-up and to select the best tests for definitive diagnosis.
Topics: Anemia; Anemia, Macrocytic; Anemia, Megaloblastic; Diagnosis, Differential; Erythrocyte Count; Erythrocyte Indices; Erythrocytes; Humans
PubMed: 23480230
DOI: 10.1111/ijlh.12082 -
American Family Physician Feb 2009Macrocytosis, generally defined as a mean corpuscular volume greater than 100 fL, is frequently encountered when a complete blood count is performed. The most common... (Review)
Review
Macrocytosis, generally defined as a mean corpuscular volume greater than 100 fL, is frequently encountered when a complete blood count is performed. The most common etiologies are alcoholism, vitamin B12 and folate deficiencies, and medications. History and physical examination, vitamin B12 level, reticulocyte count, and a peripheral smear are helpful in delineating the underlying cause of macrocytosis. When the peripheral smear indicates megaloblastic anemia (demonstrated by macro-ovalocytes and hyper-segmented neutrophils), vitamin B12 or folate deficiency is the most likely cause. When the peripheral smear is non-megaloblastic, the reticulocyte count helps differentiate between drug or alcohol toxicity and hemolysis or hemorrhage. Of other possible etiologies, hypothyroidism, liver disease, and primary bone marrow dysplasias (including myelodysplasia and myeloproliferative disorders) are some of the more common causes.
Topics: Alcohol Drinking; Algorithms; Anemia, Macrocytic; Anemia, Megaloblastic; Blood Cell Count; Diagnosis, Differential; Drug-Related Side Effects and Adverse Reactions; Erythrocyte Count; Erythrocyte Indices; FIGLU Test; Folic Acid Deficiency; Humans; Hypothyroidism; Liver Diseases; Myeloproliferative Disorders; Neural Tube Defects; Predictive Value of Tests; Reticulocyte Count; Risk Factors; Sensitivity and Specificity; Vitamin B 12 Deficiency
PubMed: 19202968
DOI: No ID Found -
Acta Haematologica 1979
Topics: Agglutinins; Anemia, Macrocytic; Autoantibodies; Cold Temperature; Diagnostic Errors; Erythrocyte Count; Hemoglobins; Humans; Male; Middle Aged
PubMed: 105543
DOI: 10.1159/000207628 -
Praxis Jun 2005
Topics: Aged; Anemia, Macrocytic; Anemia, Megaloblastic; Bone Marrow; Diagnosis, Differential; Erythrocyte Volume; Erythrocytes, Abnormal; Folic Acid Deficiency; Hemoglobinometry; Humans; Male; Megaloblasts; Vitamin B 12 Deficiency
PubMed: 16033025
DOI: 10.1024/0369-8394.94.26.1051 -
La Revue Du Praticien Apr 1998
Comparative Study Review
Topics: Adult; Aged; Alcoholism; Anemia, Macrocytic; Female; Folic Acid; Folic Acid Deficiency; Humans; Hydroxocobalamin; Hypothyroidism; Infant, Newborn; Liver Failure; Male; Pregnancy; Risk Factors; Time Factors; Vitamin B 12; Vitamin B 12 Deficiency
PubMed: 11767337
DOI: No ID Found -
The Yale Journal of Biology and Medicine Dec 1948
Review
Topics: Anemia; Anemia, Macrocytic; Female; Folic Acid; Humans; Pregnancy
PubMed: 18105406
DOI: No ID Found