CBC Reporting Update: Addition of Absolute Values

Effective April 19, 2021, Clinical Pathology Laboratories (CPL) will begin reporting absolute WBC counts with age- and gender-stratified reference ranges, in addition to the relative percentage WBC differential for the unit codes listed below. This change will also include reporting absolute immature granulocyte count (IG#) in addition to the relative immature granulocyte percentage (IG%). This is the second of several planned CBC reporting updates.

Under most circumstances, clinically relevant WBC elevations and decreases are defined by absolute counts rather than relative percentages. Current recommendations from the College of American Pathologists (CAP) and the Clinical and Laboratory Standards Institute (CLSI), recommend that absolute counts of the WBC differential be reported and used for patient management.

Important notes:

• Current state-of-the-art CBC instrumentation assesses many 1000’s of WBC’s in automated differentials to provide higher accuracy and precision with shorter turn-around-time for the significant majority of samples.
• The analyzer algorithms interpret signals from WBC, RBC and platelet channels to alert laboratory scientists of an abnormal pathological specimen for manual assessment of smear morphology.
• On smear review, the laboratory has specific criteria to replace automated WBC differential with manual differential and morphology.
• In the event of a manual differential, the laboratory will also provide the precise automated absolute WBC differential count for clinical use.
• After slide review, the technologist will note if criteria are met for pathologist slide review.

Over the course of the year, CPL will make additional changes to CBC reporting to more closely align with widely accepted laboratory standards. These include the following changes (implemented in the order listed):

• Discontinuing reference intervals for the relative WBC differentials as these will be superfluous.
• Retiring unit codes 1011, 1014, 1016, 1017 (these orderable codes currently provide absolute WBC counts for subsets of the WBC differential and will become redundant).

Please contact your CPL Account Representative should you have any questions regarding the changes described above.