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
>
>
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|