See the general documentation on second day laboratory exams.
Also, see the documentation for the primary exam data for Laboratory 25 (HE). The Beckman Coulter® MAXM instrument in the MEC produces a complete blood count on blood specimens and provides a distribution of blood cells for all participants.
Participants aged 16-69 years who do not meet any of the exclusion criteria are eligible.
Description of Laboratory Methodology
The methods used to derive CBC parameters are based on the Beckman
Coulter® method of counting and sizing, in combination with an automatic
diluting and mixing device for sample processing, and a single beam photometer for hemoglobinometry. The WBC differential uses VCS technology. See Chapter 7 of the NHANES Laboratory/Medical Technologists Procedures Manual for details.
Data Processing and Editing
Blood specimens were measured at the NHANES Mobile Examination Centers. Detailed specimen collection and processing instructions are discussed in the NHANES Laboratory/Medical Technologists Procedures Manual (LPM). Read the LABDOC file for detailed data processing and editing protocols. The analytical methods are described in the Description of the Laboratory Methodology section.
Laboratory Quality Assurance and Monitoring
The NHANES quality control and quality assurance protocols (QA/QC) meet the 1988 Clinical Laboratory Improvement Act mandates. Detailed quality control and quality assurance instructions are discussed in the NHANES Laboratory/Medical Technologists Procedures Manual (LPM). Read the LABDOC file for detailed QA/QC protocols.
The second day exam data was a convenience sample and thus did not have sample weights. The analysis of NHANES laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES Household Questionnaire Data files contain demographic data, health indicators, and other related information collected during household interviews. The Phlebotomy Examination file includes auxiliary information such as the conditions precluding venipuncture. The Household Questionnaire and Phlebotomy Examination files may be linked to the laboratory data file using the unique survey participant identifier SEQN.
Derived variables were created using the following calculation:
LB2LYMNO = LB2WBCSI * LB2LYPCT/100
LB2MONO = LB2WBCSI * LB2MOPCT/100
LB2NENO = LB2WBCSI * LB2NEPCT/100
LB2EONO = LB2WBCSI * LB2EOPCT/100
LB2BANO = LB2WBCSI * LB2BAPCT/100
The five count variables are:
Segmented neutrophils number (LB2NENO)
Lymphocyte number (LB2LYMNO)
Monocyte number (LB2MONO)
Eosinophil number (LB2EONO)
Basophil number (LB2BANO)