RT Book, Section
A1 Lichtman, Marshall A.
A1 Kaushansky, Kenneth
A1 Prchal, Josef T.
A1 Levi, Marcel M.
A1 Burns, Linda J.
A1 Armitage, James O.
SR Print(0)
ID 1133362287
T1 Classification of Anemias and Polycythemias
T2 Williams Manual of Hematology, 9e
YR 2017
FD 2017
PB McGraw-Hill Education
PP New York, NY
SN 9781259642470
LK hemonc.mhmedical.com/content.aspx?aid=1133362287
RD 2024/04/19
AB Clinically  significant  red  cell  disorders  can  be  classified  into:—  Disorders  in  which  the  red  cell  mass  is  decreased  (anemias).  The  principal  effect  is  decreased  oxygen-carrying  capacity  of  the  blood.  Their  severity  is  best  expressed  in  terms  of  hemoglobin  concentration.—  Disorders  in  which  the  red  cell  mass  is  increased  (polycythemias  also  known  as  erythrocytoses).  The  principal  effect  is  related  to  an  increased  viscosity  of  the  blood  (see  Figure  2–1).  In  addition  to  their  specific  effects,  they  are  best  expressed  in  terms  of  packed  red  cell  volume  (hematocrit).The  red  cell  mass  is  the  volume  of  the  mass  of  red  cells  in  the  circulation.—  The  normal  red  cell  mass  among  women  is  23  to  29  mL/kg.—  The  normal  red  cell  mass  among  men  is  26  to  32  mL/kg.—  More  accurate  formulas  based  on  body  surface  have  been  recommended.Because  the  red  cells  are  measured  either  as  a  concentration  in  the  blood  as  the  red  cell  count,  the  hemoglobin  content  of  the  blood,  or  the  hematocrit  (packed  red  cell  volume  per  100  mL  of  blood),  rather  than  the  volume  of  the  red  cell  mass  in  the  total  circulation,  the  anemias  and  polycythemias  can  each  be  subclassified  as:—  Relative,  where  the  red  cell  mass  is  normal  but  the  amount  of  plasma  is  increased  (relative  anemia)  or  decreased  (polycythemia)—  Absolute,  where  the  red  cell  mass  is  decreased  (true  anemia)  or  increased  (true  polycythemia)The  various  types  of  anemia  are  classified  in  Table  2–1.It  is  essential  that  the  specific  cause  of  anemia  be  determined.  The  initial  laboratory  approach  to  the  diagnosis  of  anemia  follows,  and  these  four  studies  should  be  the  prelude  to  guide  further  specific  testing.—  Hematocrit,  hemoglobin,  or  red  cell  count  to  determine  degree  of  anemia.  In  most  cases,  these  three  variables  are  closely  correlated.  Hemoglobin  concentration  is  the  most  direct  measure  of  oxygen-carrying  capacity.—  Red  cell  indices,  such  as  mean  cell  volume  (MCV),  mean  cell  hemoglobin  (MCH),  and  mean  cell  hemoglobin  concentration  (MCHC)  to  determine  whether  normocytic,  macrocytic,  or  microcytic  and  normochromic  or  hypochromic  red  cells  are  present  on  average—  Measurement  of  red  cell  distribution  width  (RDW)  to  obtain  a  measure  of  anisocytosis—  Reticulocyte  count  or  index  to  estimate  whether  marrow  response  suggests  inadequacy  of  red  cell  production  or  an  appropriate  erythropoietic  response  to  hemolysis  (or  acute  bleeding).  The  latter  is  usually  readily  apparent  clinically.—  Examination  of  the  blood  film  to  determine  red  cell  size  and  shape,  hemoglobin  content,  presence  of  red  cell  inclusions,  presence  of  agglutination  or  rouleaux  formation,  nonhematopoietic  particles  such  as  parasites  (ie,  Babesia  and  Plasmodium  species)  and  helminths  (ie,  Wuchereria  bancrofti,  nematodes),  and  accompanying  abnormalities  of  white  cells  and  plateletsImportant  caveats:—  Red  cell  size  and  hemoglobin  content  are  best  determined  from  their  indices  because  the  blood  film  will  usually  make  evident  only  gross  deviations  (eg,  the  need  to  estimate  red  cell  volume  from  a  two-dimensional  area).  Moreover,  the  blood  in  macrocytic  anemia  usually  contains  many  microcytic  cells  and  in  microcytic  anemias,  many  normocytic  cells,  which  make  determination  of  the  average  red  cell  volume  from  a  blood  film  difficult.—  In  general,  the  abnormalities  in  size,  ...