[CK] Troponin. Significance > 20% with elevated first Tn or >50% from small initial Tn. (more than 50% = BIG THING!)

Myocardial infarction: 3HR -> 24HR. (peak) ~ 10days. 

• distinct rise and fall
• typically rise 4-8 hours post onset of symptoms in MI
• peaks at 18-24 hours
• levels stay elevated for 10 days (allows late diagnosis of MI, may detect re-infarction with serial testing)

Advantages

• widely available
• high familiarity
• rises over 4-8 hours, peaks at 10-24 hours, declines over 10 days
• can be used to detect reinfarction
• predicts outcome/ mortality (if negative, then low risk 30 day outcomes)
• area under the curve of troponin elevation correlates with infarct size
• new assays are highly sensitive

Disadvantages

• low specificity: multiple causes of raised troponin other than infarction e.g. PE and RV strain (see above)
• different reference ranges for different assays
• elevated baseline troponin in renal failure
• diagnosis of infarction often requires repeated tests leading to a delay in diagnosis
• ‘washout’ occurs after reperfusion
• unclear significance of raised troponin post-cardiac surgery

What is considered a “significant change” in hsTn levels? 4

• According to the European Society of Cardiology (ESC):
• Increase of ≥20% if first Tn elevated, or
• Increase of ≥50% in patients with small initial Tn elevations

https://www.aliem.com/2013/09/high-sensitivity-troponin-testing/