David Williams wrote:
>A recent request for CKMB revealed a total CK of 778 IU/L and a CKMB of 1449
>IU/L (both were measured using Roche reagents). Other tests and controls
in the
>batch did not reveal any such anomalies.
>I have a vague recollection of this sort of effect possibly being caused by
>binding of the enzyme to an immunoglobulin.
>
>Any other ideas?
and Salvadore Sena gave an excelent summary
The only thing I would like to add is that when using a CKMB
immuno-inhibition assay, a result with the activity greater than 20% is
highly suspicious of macro-CK type 1 (a CK-BB-immunoglobulin complex) and
should be repeated on an MB mass assay. Indeed our policy for some remote
vitros analysers is to repeat all positive CK-MBs as small amount of
macro-CK create believable results that may be acted on, whereas gross
results (eg MB activity higher than total CK activity) are obviously wrong
and are easily spotted by the lab or ignored by the clinician.
>From memory some sudies show the frequency of macro-CK type 1 to be as high
as 2%, especially in the elderly population. The association with other
diseases is poor and the main issue for the patient is wrong diagnosis!
Best wishes,
Graham
Graham Jones
Staff Specialist in Chemical Pathology
St Vincent's Hospital, Sydney
Victoria St, Darlinghurst, 2010
NSW, Australia
Ph: (02) 9361-2170 Fax (02) 9361-2489
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