Title:
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The pathophysiology of cardiac troponin elevation in
chronic kidney disease : proposed mechanisms
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The measurement of the cardiac troponins has produced a paradigm shift in the
management of cardiac disease. Elevation of cTn without acute myocardial infarction
(AMI) also occurs in non-cardiac patients including those with chronic kidney disease
(CKD). Cardiovascular disease accounts for 50% of mortality in CKD. In this thesis, the
prognostic value of cTn elevation in CKD was investigated by meta-analysis of
published data and recruitment of a CKD cohort. The relationship between elevated
cTn and cardiac imaging; the involvement of inflammation, oxidative stress and
platelet activation were investigated. The difference in cTn pre and post
haemodialysis was investigated. The forms of cTn released into the circulation in CKD
was investigated and compared to the forms released following AMI.
CKD patients positive for cTn are three times more likely to die than cTn negative
patients. Elevated cTn was not associated with extent of cardiac pathology but rather
the presence of diffuse global ischemia. Elevated cTn in CKD is associated with
increased C-reactive protein but not other markers of inflammation, oxidative stress
or platelet activation. cTn, CRP and interleukin-6 were predictive of all-cause
mortality. Following dialysis, cTnl but not cTnT adsorbs to the membrane within the
vascular compartment. Intact cTnT and cTnl were observed in CKD patient serum by
Western blotting, which is similar to the cTn forms of observed following myocardial
infarction. Some lower molecular weight fragments are demonstrable but their
presence is method dependent and heterogeneous between patients.
Elevated cTn is of prognostic value in CKD and reflects the high incidence of
cardiovascular disease and cardiac death. Elevated cTn is not a false positive. The
mechanism of cTn release in CKD remains to be understood. The clinical challenge is
for the renal physician to translate the potential for cardiovascular disease
monitoring conferred by cTn into improved patient management.
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