Various Factors Influence Cardiac Troponin Concentrations

Cardiovascular diseases are the second most common cause of death in Japan, and the number of new cases is continuously growing. Among the cardiovascular diseases, one-third is attributed to ischemic heart diseases including acute myocardial infarction (AMI).

Cardiac troponin I is a protein that is specifically expressed in cardiomyocytes and is eluted in the blood when cardiomyocytes are injured such as by ischemia. Due to its specificity, cardiac troponin I has become one of the most reliable biomarkers for the diagnosis of AMI.

Scientists at the Japanese Red Cross Medical Center (Tokyo, Japan) and their colleagues enrolled a total of 698 apparently healthy individuals (385 females and 313 males) between the ages of 23 and 86 who visited the Medical Center for a health checkup from January through April in 2014 were included in this study.

The team performed routine biochemistry tests on a BioMajesty JCA-BM6070 clinical biochemistry analyzer that included the assays for aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyl transferase (GGT), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), creatinine (Cre), hemoglobin A1c (HbA1c), and lactate dehydrogenase (LDH). Serum samples were used for the measurement of all the assays except for HbA1c, which was measured with whole-blood samples.

The Abbott Laboratories’ STAT high-sensitive troponin I (hsTnI) was performed for the measurement of cardiac troponin I on Architect i2000. The limit of detection (LoD) of the assay was 1.9 pg/mL, the lowest concentration where 10% coefficient of variation (CV) was supported was 4.7 pg/mL and the overall 99th percentile was 26.2 pg/mL. The CardioPhase high-sensitive C-reactive protein (hsCRP) tests were performed for the measurement of CRP. The limit of detection (LoD) of the assay was 0.175 mg/L, the CV was 7.6% at 0.410 mg/L and the reference value was 3 mg/L.

The scientists found that the 99th percentile of the hsTnI in the overall population was 22.5 pg/mL, 17.7 pg/mL for females and 30.6 pg/mL for males. The median of the hsTnI in the overall population was 3.2 pg/mL, 2.6 pg/mL for females and 4.0 pg/mL for males. The age and gender had a significant influence on these values. The troponin I level also showed significant associations with the body mass index (BMI), the gamma glutamyl transferase (GGT), lactate dehydrogenase (LDH), estimated glomerular filtration rate (eGFR), and cardiac abnormalities by electrocardiography (ECG), but not with the high-sensitive C-reactive protein (hsCRP) level.

The authors concluded that the 99th percentiles of the troponin I measured in the general population in Japan were comparable as the ones derived in the USA, Germany, and Singapore. The troponin I level was dependent on the gender, age, BMI, and cardiac abnormalities found by electrocardiogram (ECG) but not by the hsCRP level. The study was published on August 1, 2017, in the Journal of Clinical Laboratory Analysis.

Related Links:
Japanese Red Cross Medical Center