What is the normal value for high sensitivity troponin (hs-troponin)?

Normal Values for High Sensitivity Troponin

The normal value for high sensitivity troponin (hs-troponin) is below the 99th percentile upper reference limit, which varies by assay type and sex, with common cutoffs being <14 ng/L for hs-cTnT and <26 ng/L for hs-cTnI, though sex-specific thresholds are increasingly recommended (men: 34 ng/L, women: 16 ng/L for hs-cTnI). 1

Assay-Specific Reference Values

• For high-sensitivity cardiac troponin T (hs-cTnT), the 99th percentile upper reference limit is generally established at 14 ng/L 1
• For high-sensitivity cardiac troponin I (hs-cTnI), the 99th percentile upper reference limit is approximately 26 ng/L when using the Abbott ARCHITECT assay 1
• Sex-specific thresholds are increasingly recommended, with different cutoffs for men (34 ng/L) and women (16 ng/L) for hs-cTnI, as women naturally have lower troponin values 2
• The limit of detection varies among different hs-cTn assays, typically between 1 ng/L and 5 ng/L 1

Factors Affecting Normal Values

• Age significantly impacts normal troponin values - older patients have higher baseline levels even without acute cardiac injury 3
• Renal function is a strong predictor of troponin levels - patients with reduced estimated glomerular filtration rate (eGFR) commonly have higher baseline troponin levels 1, 3
• Sex differences are notable - men generally have higher baseline troponin levels than women of the same age 3, 2
• In patients with normal renal function, the 99th percentile for hs-cTnT among men and women under 50 years is approximately 20 ng/L and 12 ng/L respectively, increasing to 44 ng/L and 36 ng/L by age 70-79 years 3

Clinical Interpretation Considerations

• A value above the 99th percentile does not automatically indicate myocardial infarction - serial measurements showing a rise and/or fall pattern are required 1
• For diagnosis of acute myocardial necrosis, evidence of a serial increase or decrease ≥20% is required if the initial value is elevated 1
• For values below or close to the 99th percentile, evidence for acute myocardial necrosis is indicated by a change of ≥3 standard deviations around the initial value 1
• Absolute changes in ng/L have higher diagnostic accuracy for AMI than relative changes 1

Common Pitfalls in Interpretation

• Solitary elevations of troponin should not be assumed to be due to myocardial infarction - many conditions can cause troponin elevation including tachyarrhythmias, heart failure, hypertensive emergencies, sepsis, and renal insufficiency 1
• Patients with end-stage renal disease frequently have elevated cardiac troponin levels even without clinical evidence of acute coronary syndrome 1
• High-sensitivity assays can detect troponin in the blood of most healthy people, making serial changes more important than absolute values 1
• The U.S. FDA has restricted reporting of hs-cTnT results to concentrations of 6 ng/L (limit of quantification) or greater, which affects some diagnostic protocols 1

Reporting Units

• High-sensitivity troponin values are reported in nanograms per liter (ng/L) rather than the fractional results (ng/mL) used with conventional assays 1
• This change results in whole numbers (e.g., 25 ng/L) rather than decimal values (0.025 ng/mL), which improves clarity and safety in interpretation 1

Understanding these normal values and their interpretation is critical for accurate diagnosis of myocardial injury and infarction, particularly as high-sensitivity assays have increased detection capabilities but decreased specificity compared to conventional assays.