赤血球容積粒度分布幅, red cell distribution width, red blood cell distribution width

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the 18th letter of the Roman alphabet (同)r

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resistance / 17歳以下父兄同伴映画の表示 / rook

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/08/04 03:00:52」(JST)

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Human red blood cells

Red blood cell distribution width (RDW or RCDW) is a measure of the range of variation of red blood cell (RBC) volume that is reported as part of a standard complete blood count. Usually red blood cells are a standard size of about 6-8 μm in diameter. Certain disorders, however, cause a significant variation in cell size. Higher RDW values indicate greater variation in size. Normal reference range in human red blood cells is 11.5-14.5%.^[1] If anemia is observed, RDW test results are often used together with mean corpuscular volume (MCV) results to determine the possible causes of the anemia. It is mainly used to differentiate an anemia of mixed causes from an anemia of a single cause.

Deficiencies of Vitamin B₁₂ or folate produce a macrocytic anemia (large cell anemia) in which the RDW is elevated in roughly two-thirds of all cases. However, a varied size distribution of red blood cells is a hallmark of iron deficiency anemia, and as such shows an increased RDW in virtually all cases. In the case of both iron and B₁₂ deficiencies, there will normally be a mix of both large cells and small cells, causing the RDW to be elevated. An elevated RDW (red blood cells of unequal sizes) is known as anisocytosis.^[2]

An elevation in the RDW is not characteristic of all anemias. Anemia of chronic disease, hereditary spherocytosis, acute blood loss, aplastic anemia (anemia resulting from an inability of the bone marrow to produce red blood cells), and certain hereditary hemoglobinopathies (including some cases of thalassemia minor) may all present with a normal RDW.^[3]

Calculations

The "width" in RDW is sometimes thought of as "misleading," since it in fact is a measure of deviation of the volume of RBCs, and not directly the diameter. However, "width" refers to the width of the volume curve (distribution width), not the width of the cells. Thus, it is a reasonably accurate term.^[4]^[5]

Mathematically the RDW is calculated with the following formula:

RDW = (Standard deviation of MCV ÷ mean MCV) × 100.^[6]

Pathological Implications

Normal RDW

When anemia is seen in the presence of a normal RDW, one must have a high suspicion towards Thalassemia as the cause of anemia and a Mentzer Index should be done from the CBC report itself to confirm.

High RDW

Iron Deficiency Anemia: usually presents with high RDW with low MCV

Folate and vitamin B12 deficiency anemia: usually presents with high RDW and high MCV

Mixed Deficiency (Iron + B12 or folate) anemia: usually presents with high RDW with MCV being high, low or often normal range

Recent Hemorrhage: typical presentation is high RDW with normal MCV

A false high RDW reading can occur if EDTA anticoagulated blood is used instead of citrated blood. See Pseudothrombocytopenia.

References

^ "Red Cell Distribution Width". Family Practice Notebook. Retrieved 18 October 2013.
^ The red blood cell distribution width.
^ Table 1.4 in: Kjeldsberg, Carl R.; Perkins, Sherrie L.. Practical Diagnosis of Hematologic Disorders. American Society for Clinical Pathology. ISBN 089189571X. 5th edition.
^ Pomeranian Medical University > Red blood cell indices (indexes) Retrieved on 5 April 2009
^ Cornell University, Department of Population Medicine & Diagnostic Sciences > Red Cell Distribution Width (RDW) Last Updated: June 2000. Retrieved on 5 April 2009
^ Encyclopedia of Surgery: A Guide for Patients and Caregivers Red blood cell indices Retrieved on 5 April 2009

UpToDate Contents

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1. 平均赤血球容積 mean corpuscular volume
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. 貧血を有する小児に対するアプローチ approach to the child with anemia
4. 自動血液分析装置 automated hematology instrumentation
5. 末梢血塗抹標本の評価 evaluation of the peripheral blood smear

English Journal

Assessment of mutagenic, hematological and oxidative stress biomarkers in liver of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) in response to sublethal verapamil exposure.

Ajima MNO1,2, Pandey PK2, Kumar K2, Poojary N2.
Drug and chemical toxicology.Drug Chem Toxicol.2017 Jul;40(3):286-294. doi: 10.1080/01480545.2016.1219914. Epub 2016 Aug 25.
PMID 27560095

Relation of Red Cell Distribution Width to Left Ventricular End-Diastolic Pressure and Mortality in Patients With and Without Heart Failure.

Senthong V1, Hudec T2, Neale S3, Wu Y4, Hazen SL5, Tang WH6.
The American journal of cardiology.Am J Cardiol.2017 May 1;119(9):1421-1427. doi: 10.1016/j.amjcard.2017.01.036. Epub 2017 Feb 10.
PMID 28285713

The Relation Between No-Reflow Phenomenon and Complete Blood Count Parameters.

Celik T1, Balta S1, Mikhailidis DP2, Ozturk C1, Aydin I3, Tok D4, Yildirim AO1, Demir M1, Iyisoy A1.
Angiology.Angiology.2017 May;68(5):381-388. doi: 10.1177/0003319716659193. Epub 2016 Jul 14.
PMID 27418628

Japanese Journal

rdwラットの下垂体および副腎機能

TOHEI Atsushi,UMEZU Motoaki,KANAI Takao,YAMAGUCHI Keiichiro,KOSAKU Akinori,KON Hiroe,SHINODA Motoo
Experimental animals 59(1), 95-98, 2010-01-01
… The rdw rat is a hereditary hypothyroid strain isolated from Wistar-Imamichi rats. … In the present study, adrenocorticotropic hormone (ACTH) and corticosterone responses to restraint stress (120 min) were examined in rdw adult male rats. … ACTH response to restraint stress was higher in rdw rats than in hetero control rats. … The plasma concentrations of corticosterone were lower in rdw rats than in control rats during the first 30 min after the onset of stress. …
NAID 10027852731

Genotypic differences in root traits of rice (Oryza sativa L.) seedlings grown under different soil environments

Matsuo Naoki,Mochizuki Toshihiro
Plant Root 3(0), 17-25, 2009
… Using 70 rice varieties from four agricultural ecotypes (i.e. japonica upland (JU), japonica lowland (JL), indica upland (IU), and indica lowland (IL)), we examined the effects of genotypes, environment and their interaction on seminal root length (SRL), seminal root thickness (SRT), number of crown roots (NCR), root and shoot dry weight (RDW and SDW) and root/shoot ratio (R/S ratio). …
NAID 130000137949

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