Dear Dr. Steiner,
I'm a clinical chemist but, like you must be, becoming more knowledgable in
hematology, so I do have some responses to your questions:
>1. Do we need to establish critical limits for both haemoglobin and
>haematocrit which run in parallel in over 99% of all clinical situations?
No, one is enough. I would use hemoglobin, although ours at
Wisconsin currently is a hematocrit <20% or >55%.
>2. Does it make sense to set up an upper limit for the platelet count?
Maybe not, although ours is a very high >1000 x 109/L, which
probably only occurs in a myeloproliferative process; if you call, you can
ask about symptoms, suggest a blood smear if not done already to check for
platelet abnormalities, etc.
>3. What about qualitative measures (blasts, immature cells, plasmodia etc.)?
If the sample is from an out-patient, we call to notify the
ordering source, but only after checking if a previous test result was
already reported as a similar abnormality.
>4. Is it clinically useful to introduce a limit for absolute neutropenia
>and if >so, at what count (1000/µl or less?)?
We use a limit <2000/µL, only on outpatients (again, checking to
see if recent previous results were reported with a similar abnormality).
>5. How do you (clinically meaningful) define pancytopenia?
We don't, except by individual cell parameters.
>6. At what levels should delta checks be set in haematology analyzers?
This decision varies based on your patient population and how
proactive you want to be in informing your clinicians and patient units of
changes vs. your sensitivity to analytical problems.
>7. Do we need to handle haematology/oncology and/or ICU patients in a
>different way (more strictly set limits?)?
Yes; as implied above, we've set some limits for outpatients that
are different (or nonexistent) for inpatients.
Dave Koch, Ph.D.
Associate Professor, Pathology & Laboratory Medicine
University of Wisconsin
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