関: megaloblastic anemia

WordNet

a deficiency of red blood cells (同)anaemia
a lack of vitality (同)anaemia
genus of terrestrial or lithophytic ferns having pinnatifid fronds; chiefly of tropical America (同)genus Anemia

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/07/12 19:03:12」(JST)

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The term macrocytic is from Greek words meaning "large cell". A macrocytic class of anemia is an anemia (defined as blood with an insufficient concentration of hemoglobin) in which the red blood cells (erythrocytes) are larger than their normal volume. The normal erythrocyte volume in humans is about 80 to 100 femtoliters (fL= 10⁻¹⁵ L). In metric terms the size is given in equivalent cubic micrometers (1 μm³ = 1 fL). The condition of having erythrocytes which (on average) are too large, is called macrocytosis. In contrast, in microcytic anemia, the erythrocytes are smaller than normal.

In a macrocytic anemia the larger red cells are always associated with insufficient numbers of cells and often also insufficient hemoglobin content per cell. Both of these factors work to the opposite effect of larger cell size, to finally result in a total blood hemoglobin concentration that is less than normal (i.e., anemia).

Macrocytic anemia is not a disease in the sense of having a single pathology, but is rather a condition. As such, it is the class name for a set of pathologies that all produce somewhat the same red blood cell abnormality. Many specific pathologies are known which result in macrocytic-type anemias. Some of these produce slightly different sets of appearances in blood cells that are detectable from red and white cell morphology, and others are only detectable with chemical testing.

Types of macrocytic anemias

Megaloblastic anemias (DNA replication disorders)

Especially common causes of macrocytic anemias are the so-called megaloblastic anemias, in which cells are larger because they cannot produce DNA quickly enough to divide at the right time as they grow, and thus grow too large before division. Causes of the DNA synthetic problem range from lack of certain vitamins needed to produce DNA (notably folate and B12), to poisons or inhibitors of DNA replication, such as some kinds of antiviral drugs and chemotherapeutic agents. Classically these megaloblastic types of anemias are associated also with more specific features, such as megaloblasts in the bone marrow, the presence of ovalocytes in the (peripheral) blood smear, and the pathognomonic presence of hypersegmented neutrophils.

Red cell membrane disorders producing codocytes

Other disorders which cause macrocytosis without DNA replication problems (i.e., non-megaloblastic macrocytic anemias), are disorders associated with increased red cell membrane surface area, such as pathologies of the liver and spleen which produce codocytes or "target cells" which have a central collection of hemoglobin surrounded by a pallor (a thin area) then followed by a thicker collection of hemoglobin at the rim of the cell.

Alcohol

Round macrocytes which are not codocytes are produced in chronic alcoholism (which produces a mild macrocytosis even in the absence of vitamin deficiency), apparently as a direct toxic effect of alcohol specifically on the bone marrow.^[1]

Association with rapid red cell turnover and reticulocytosis

Mild macrocytosis is a common finding associated with rapid blood restoration or production, since in general, "fresh" or newly produced red cells (reticulocytes) are larger than the mean (average) size, due to slow shrinkage of normal cells over a normal red cell circulating lifetime. Thus, chronic obstructive pulmonary disease (COPD), in which red cells are rapidly produced in response to low oxygen levels in the blood, often produces mild macrocytosis. Also, rapid blood replacement from the marrow after a traumatic blood loss, or rapid red blood cell turnover from rapid hemolysis (G6PD deficiency), also often produces mild macrocytosis in the associated anemia.^[2]

References

^ Macrocytosis eMedicine; Maakaron et al.
^ Macrocytosis eMedicine; Maakaron et al.

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1. 大赤血球症 macrocytosis
2. 貧血を有する成人患者に対するアプローチ approach to the adult patient with anemia
3. 平均赤血球容積 mean corpuscular volume
4. 貧血を有する小児に対するアプローチ approach to the child with anemia
5. アルコール乱用と血液疾患 alcohol abuse and hematologic disorders

English Journal

An Ethanolic Extract of Black Cohosh Causes Hematological Changes but Not Estrogenic Effects in Female Rodents.

Mercado-Feliciano M, Cora MC, Witt KL, Granville CA, Hejtmancik M, Fomby L, Knostman KA, Ryan MJ, Newbold R, Smith C, Foster PM, Vallant MK, Stout MD.SourceNational Toxicology Program, National Institute of Environmental Health Sciences, National Institutes of Health, 111 Alexander Drive, Research Triangle Park, NC USA.
Toxicology and applied pharmacology.Toxicol Appl Pharmacol.2012 Jun 8. [Epub ahead of print]
Black cohosh rhizome (Actaea racemosa) is used as a remedy for pain and gynecological ailments; modern preparations are commonly sold as ethanolic extracts available as dietary supplements. Black cohosh was nominated to the National Toxicology Program (NTP) for toxicity testing due to its widespread
PMID 22687605

New erythrocyte and reticulocyte parameters on CELL-DYN Sapphire: analytical and preanalytical aspects.

Ermens AA, Hoffmann JJ, Krockenberger M, Van Wijk EM.SourceClinical Laboratory, Amphia Hospital, Breda, the Netherlands.
International journal of laboratory hematology.Int J Lab Hematol.2012 Jun;34(3):274-82. doi: 10.1111/j.1751-553X.2011.01391.x. Epub 2011 Dec 8.
INTRODUCTION: Extended RBC and reticulocyte parameters are useful in diagnosing functional iron deficiency and various other clinical conditions. The newest software of the CELL-DYN Sapphire measures extended RBC and reticulocyte parameters. The aims of the present communication were to assess the a
PMID 22151199