Realizing that Im revisiting an often visited topic, I now have to poll the
group for its opinion.
My institution is going to a written policy of serum specimens (SST) for
outpatient/outreach patients and plasma specimens (PST) for inpatients.
Because of the differences between plasma and serum potassium reference
ranges and because our LIS cannot easily accomodate two reference ranges for
the same orderable, I recommended that the plasma reference range (3.4 - 5.0
mmol/L) be reported with the following comment:
Listed reference range is for inpatient (plasma) specimens.
Reference range for outpatient (serum) specimens is 3.6 - 5.2
mmol/L.
There is a school of thought within the lab that goes since the difference
(0.2 mmol/L) is within the instrument precision, one reference range without
a comment should be sufficient. I disagree with this belief since I feel
that disregard to the difference between serum and plasma potassium values
with a stated policy of serum specimens for one group of patients and plasma
for another would be misleading to clinicians.
Please reply with your opinion to this issue.
Thank you
David Alter, MD
Spectrum Health
MI
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