All analysis was according to the manufacturers instructions. The assumption is that there are no circulating CK-BB or other forms, and that the enzymatic activity of subunits B and M are equal. Although no CK-BB subunit is present in serum from normal individuals, circulating levels have been reported in various pathological conditions, and the presence of this subunit interferes in routine assays, as highlighted by the cases in table 1. These results, however, were not consistent with myocardial tissue involvement, as shown by the low CK-MB mass index and the negative cTNT result. The latter results in erroneous CK-MB data, occasionally exceeding total CK activity.
T are predominant in regenerating skeletal muscle fiber and in patients with polymyositis.
This was reflected in results obtained from patient no. 4, where although no clinical evidence of AMI was present, significantly elevated CK-MB mass and relative mass index were observed. The claim that a third-generation assay is more specific needs to be investigated. 1 and 4 were consistent with skeletal involvement, however, CK-MB relative index was low in patient no. 1, compared to that observed in patient no. 4. These markers should initially be requested on the basis of clinical evidence, and ideally following an agreed protocol. Additionally, biochemical findings should be interpreted with caution, and adequate clinical data must always accompany laboratory requests.