Intriguing Troponin Series
I recently was asked to comment on a series of troponin values from a general hospital.
Since this is a series of extremely high troponin, an MI was suspected. Although the EKG/ECG was not normal, there was no evidence of an AMI.
The apparent "change" in the TnI is probably due to the random error rather than a physiological change.
Table: Troponin Series
|Day ||Time ||Troponin 1 |
| 1|| 1325|| 2.6|
| 1|| 1724|| 2.4|
| 1|| 2035|| 2.3|
| 2|| 0248|| 2.2|
| 2|| 0646||2.1 |
I am sorry to say that, by the time I was asked to comment on this, the sample was gone and the patient had been discharged. My response had the sample still been available was to suggest that one or more of the samples be mixed 1+1 and 1+3 with a sample with a very low TnI level (approx. 0). Then assay the unmixed sample(s) and the dilutions. If the sample contained a heterophilic antibody (my thought) the values would not show linearity. If the troponin were truly TnI the sample would show linearity. Another/additional test would be to measure a not constituent measured by immunoassay such as TSH or hCG. A high value in these would also indicate a heterophilic antibody.
An interesting article on salivary cTnI appeared recently. In a group of 30 confirmed AMI and 28 non-MI
the cTnI were measured in both serum and saliva. The interquartile range for the saliva was 0.08-0.23 and for the AMI patients at 12 hrs. post-admission the range was 2.7-11.6 and at 24 hrs. the range was 2.1-9.0
In a similar study by the same authors higher CK levels in saliva were also recorded.
In both cases there was a positive correlation between serum levels of both CK and cTnI and salivary levels.
Indian J Med Res. Dec 2013; 138(6): 861-865