title: [Bone marrow cellularity measurement by myelocrit].
abstract: BACKGROUND
  The bone marrow (BM) cellularity has been used as a major index for the evaluation of hematologic diseases and malignancies. However, the microscopic evaluation lacks objectivity because of considerable variations among different observers. We measured myelocrit cellularity as an objective method to evaluate the cellularity.
  
  
  METHODS
  Between November 2007 and January 2008, 489 consecutive BM aspirates including 25 cases of AML D7 marrow (7 days after initiation of chemotherapy) were examined. The conventional BM cellularity was evaluated using BM needle biopsies after hematoxylin-eosin stain. EDTA-anticoagulated BM aspirates were put into the Wintrobe tubes, centrifuged and the thickness of 5 layers from the bottom was measured: RBC, buffy coat (BC), plasma, BM particle, and fat layers. The myelocrit cellularity was defined as the ratio of BC to the BC plus fat layers.
  
  
  RESULTS
  Both of the thickness of BC layer (r=0.721, P=0.000) and the myelocrit cellularity (r=0.735, P=0.000) correlated well with the conventional cellularity. However, the AML D7 BM cellularity correlated with BC layer (r=0.589, P=0.002), but not with the myelocrit cellularity (r=0.281, P=0.231). The cellularity of the BM other than AML D7 marrow showed a better correlation with the myelocrit cellularity (r=0.826, P=0.000) than the BC layer (r=0.713, P=0.000).
  
  
  CONCLUSIONS
  The myelocrit is a simple, reproducible and objective method to determine the BM cellularity. For accurate assessment of BM cellularity, measurement of the thickness of BC layer in AML D7 BM and of the myelocrit cellularity in other BM samples has better be used.
authors.affiliation: Department of Laboratory Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Chang
authors.forename: Hunhee
authors.initials: H
authors.lastname: Park
authors.forename: Hyojin
authors.initials: H
authors.lastname: Chae
authors.forename: Myungshin
authors.initials: M
authors.lastname: Kim
authors.forename: Yonggoo
authors.initials: Y
authors.lastname: Kim
authors.forename: Kyungja
authors.initials: K
authors.lastname: Han
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001853:Bone Marrow / Q000473:pathology*; D002469:Cell Separation / Q000295:instrumentation / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D015470:Leukemia, Myeloid, Acute / Q000473:pathology*; D008297:Male; D008875:Middle Aged