RT Book, Section
A1 Ambruso, Daniel R.
A1 Nuss, Rachelle
A1 Wang, Michael
A2 Hay, Jr., William W.
A2 Levin, Myron J.
A2 Deterding, Robin R.
A2 Abzug, Mark J.
SR Print(0)
ID 1153313268
T1 Hematologic Disorders
T2 Current Diagnosis & Treatment: Pediatrics, 24e
YR 2018
FD 2018
PB McGraw-Hill Education
PP New York, NY
SN 9781259862908
LK accessmedicine.mhmedical.com/content.aspx?aid=1153313268
RD 2022/05/20
AB The  normal  ranges  for  peripheral  blood  counts  vary  significantly  with  age.  Normal  neonates  have  a  hematocrit  of  45%–65%.  The  reticulocyte  count  at  birth  is  relatively  high  at  2%–8%.  Within  the  first  few  days  of  life,  erythrocyte  production  decreases,  and  the  values  for  hemoglobin  and  hematocrit  fall  to  a  nadir  at  about  6–8  weeks.  During  this  period,  known  as  physiologic  anemia  of  infancy,  normal  infants  have  hemoglobin  values  as  low  as  10  g/dL  and  hematocrits  as  low  as  30%.  Thereafter,  the  normal  values  for  hemoglobin  and  hematocrit  gradually  increase  until  adult  values  are  reached  after  puberty.  Premature  infants  can  reach  a  nadir  hemoglobin  level  of  7–8  g/dL  at  8–10  weeks.  Anemia  is  defined  as  a  hemoglobin  concentration  two  standard  deviations  below  the  mean  for  a  normal  population  of  the  same  gender  and  age.