david_porter

I'm not sure of the mechanism but Pottasium that has leached from the
red cells is forced through the gel giving falsely elevated serum
levels

castaway

External User

 

Posts: 1

This is news to me, we routinely respin SST vacutainers from our office
clients. Does it say why you should not respin them?


Gary

jedilworth

I remember hearing that you couldn't respin these YEARS ago (when I was
still in general lab areas and that was pre-1988). I believe it was for
the reason already cited: elevated potassium levels. You can pour off
the serum and respin THAT, however.

In the early 70's, before SST's, we spun down the clots, poured off, and
respun THAT every morning before all our chemistries were done. Also, we
used to spin with caps OFF (amazing what we did in those days). We were
short on space, so we were doing this out in the hall for a year or so
before we made the move to a "new" laboratory in 1976.

Amazing we're all still here :-).

Judy Dilworth, M.T. (ASCP)
Microbiology

shylirin

Yes... we recently had to investigate a rash of elevated potassium values
(most >5.0) and found out the main lab was respinning tubes coming in from
outreach facilities. We also had a problem with elevated Total Protein as
well, though I'm not entirely convinced it was solely due to respinning as
the problem took longer to work out than the potassium issue.

Shylirin

robert

What about the troponin issue with tiger greens?

shylirin

I'm not familiar with that one, Robert... sorry! We do very few Troponin I
tests (1 or 2 every 6 months) and we've never seemed to have a problem with
it. Anyone else know about this one?

Shylirin

mike collins

Heparin can interfere with Troponin T and some troponin I methods.
Troponin is also sensitive to microclots and fragments of gel.
All troponins should be assayed on aliquots not primary tubes and the
aliquot should be centrifuged just prior to analysis.

--
Mike Collins
UK
Mike&heather-at-oakwellmount-dot-freeserve-dot-co-dot-uk

lc

If I remember correctly, the aged serum below the gel layer contains a very
high potassium concentration due to its contact with the red cells.
Respinning the tube -- especially if spun initially in an angled head
centrifuge and respun in a floating head centrifuge -- forces some of the
serum in the lower level into the top layer, falsely elevating the potassium
value and the value any other analyte that would increase if left in contact
with the cells. The same criteria should hold true for any separator tube,
whether serum or plasma.

Since it takes a while for the potassium in the lower layer to leach out of
the cells, respinning a gel tube within an hour or two of the initial
spinning for the purpose of removing fibrin should be acceptable and give
you a valid potassium value. If the problem recurs frequently, either wait
longer to spin the tube (inserts usually suggest 20-30 mins, or 60 mins if
the patient is on heparin) or switch to heparin tubes so the problem is
moot.

If the tube was spun off-site and contains particulate matter or fibrin, we
routinely remove what we can of the serum layer and respin it in a separate
tube to clarify it before testing. We do not respun old separator tubes.


Larry Smrz, MT(ASCP)SBB
Indianapolis, IN

lynn gerber

We receive specimens that are collected at 2 offsite clinics. They
typically bring in the specimens in the evening. We usually respin the
SST's and have not had problems with the results. However, if, by chance
the tubes are kept at the clinic overnight and we then respin them, we do
have problems with elevated potassium. That has been our experience.