BACKGROUND Quantification and comparison of high-sensitivity (hs) cardiac troponin I (cTnI) and cTnT concentrations in chronic kidney disease (CKD) have not been reported. We examined the associations between hs cTnI and cTnT, cardiovascular disease, and renal function in outpatients with stable CKD. METHODS Outpatients (n = 148; 16.9% with prior myocardial infarction or coronary revascularization) with an estimated glomerular filtration rate (eGFR) of <60 mL · min−1 · (1.73 m2)−1 had serum cTnI (99th percentile of a healthy population = 9.0 ng/L), and cTnT (99th percentile = 14 ng/L) measured with hs assays. Left ventricular ejection fraction (LVEF) and mass were assessed by echocardiography, and coronary artery calcification (CAC) was determined by computed tomography. Renal function was estimated by eGFR and urine albumin/creatinine ratio (UACR). RESULTS The median (interquartile range) concentrations of cTnI and cTnT were 6.3 (3.4–14.4) ng/L and 17.0 (11.2–31.4) ng/L, respectively; 38% and 68% of patients had a cTnI and cTnT above the 99th percentile, respectively. The median CAC score was 80.8 (0.7–308.6), LV mass index was 85 (73–99) g/m2, and LVEF was 58% (57%–61%). The prevalences of prior coronary disease events, CAC score, and LV mass index were higher with increasing concentrations from both hs cardiac troponin assays (P < 0.05 for all). After adjustment for demographics and risk factors, neither cardiac troponin assay was associated with CAC, but both remained associated with LV mass index as well as eGFR and UACR. CONCLUSIONS Increased hs cTnI and cTnT concentrations are common in outpatients with stable CKD and are influenced by both underlying cardiac and renal disease.

Bladder epithelial abnormalities in interstitial cystitis may be caused by a negative autocrine growth factor that inhibits cell proliferation by down-regulating HB-EGF production. Furthermore, decreased levels of urine and serum HB-EGF indicate that interstitial cystitis may be a urinary tract manifestation of a systemic disorder.

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These findings indicate that complex changes in the levels of urine epithelial cell growth factors (EGF, IGF1, and HB-EGF) and a growth factor binding protein (IGFBP3) are associated with IC. While EGF, IGF1, and IGFBP3 levels are either the same or increased in the urine of IC patients as compared to patients with bacterial cystitis or asymptomatic controls, HB-EGF levels are significantly decreased in the urine of IC patients. Understanding the reasons for these changes may lead to understanding the pathogenesis of this disorder.