We had a similar problem in 1996. The CKMB was more than 1.6X CK. The technic
used was immunoinhibition assay (Hitachi 717). Trop was 0 and CKMBmass < 4.
The patient came to ER with non specific pain. After investigation we found
that he has prostate cancer with metastasis. So the interference we had was
from CKBB produced by prostate cancer. There are some other cancers where the
production of CKBB is increased and can interfere with CKMB inhibition, giving
percentage results higher than 100%.
Ihssan
"Sena, Salvador, Ph.D." a écrit :
> We had an interesting case nine years ago when we were still measuring CK-MB
> activity using the Vitros (then Ektachem) immunoinhibition assay. The
> measured CK-MB activity was over 2X the total CK activity (CK=372 U/L, CK-MB
> = 791 U/L, %MB = 212%). When we analyzed the sample with the CK-MB
> monoclonal antibody "mass" immunoassays on the Dade Stratus and Abbott IMx,
> there was no detectable CK-MB. On CK electrophoresis, we observed a very
> large CK-BB band, a smaller band for macro CK type 2 (mitochondrial CK), and
> no band for CK-MB. The clinical information was "metastatic adenocarcinoma
> of prostate". The patient had an extremely high level of serum PSA and
> prostatic tissue is known to contain large amounts of CK-BB. On a
> subsequent hospitalization about 3 weeks later, we obtained similar results
> with the Vitros assay. However, the CK electrophoresis no longer showed a
> band for CK-BB; instead, there was a large band cathodal to the CK-MM band,
> which we thought was macro CK type 1 (CK-BB bound to IgG), and another
> smaller band with approx. the same electrophoretic mobility as CK-MB, which
> we tentatively identified as an IgA-CK-BB complex. The Stratus and IMx
> mass assays for CK-MB were negative. In samples taken over the next few
> days, these "macro type-1" bands were no longer observed and the bands for
> CK-BB (unbound) and mitochondrial CK observed 3 weeks earlier reappeared!
> Unfortunately, the patient expired during this hospitalization. We were
> never able to explain the dynamic behaviour of the CK electrophoresis.
>
> Salvador F. Sena, Ph.D., DABCC
> Associate Director, Clinical Chemistry
> Department of Pathology and Laboratory Medicine
> Danbury Hospital
> Danbury, CT 06810 USA
> [log in to unmask]
>
> > -----Original Message-----
> > From: Les Culank [SMTP:[log in to unmask]]
> > Sent: Friday, October 27, 2000 7:17 AM
> > To: Dr David G Williams
> > Cc: [log in to unmask]
> > Subject: Re: CKMB problem
> >
> > I agree with all of our colleagues' comments about macro-CK's.
> >
> > CK-BB giving an apparent MB result of this extent is unlikely to come from
> > a recoverable degree of brain injury.
> >
> > But we have seen it on rare occasions seeming to come from several other
> > sources, including gut necrosis; myometrial damage; and neoplasia.
> >
> > Yours,
> >
> > Les
> >
> >
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