Troponin

From WardWiki - Foundation Doctor Helper

Troponin seems to attract far more attention, mythology and stress than can sensibly be attributed to a test with very clear indications and relative ease of interpretation. This will not fad quickly with time, nonetheless a simple no nonsense article is warranted to cut through as much as this as possible. For chest pain it remains a basic blood test.

Sample collection

The bottle used is either serum gel or lithium heparin, and not always the same bottle as used for U&E. This is trust specific and it is wise to check prior to sampling.

The reality

It is RELIABLY raised 12 hours after myocardial damage and by definition will NOT be raised with unstable angina. It remains elevated for five to seven days in the vast majority of patients.

The logic of holding off antiplatelets until a troponin result is similar to holding off a blood transfusion until a patient is hypotensive, oliguric and ripe for ITU.

Waking a patient at 3am just to check the troponin at exactly 12 hours shows ignorance on the part of all concerned. Three situatiuons arise for suspected ACS as follows:

1. No contraindications to antiplate agents: Give immediately, don't wait for troponin 2. Clear contraindications to antiplatelet agents: don't give them! 3. Some uncertain situation that will require at least registar approval to give antiplatelet agents - they should see the patient themselves. If they are prepared to see the patient at 4am, by all means check troponin at 3am. There is no sense and considerable discomfort to a patient in collecting a sample at an inconvenient time for it not to be acted upon at that time.

What does troponin indicate?

It indicates myocardial cell injury - that's it. The following cases have raised troponin levels

• Acute coronary syndrome
• Sepsis
• Blunt chest injury
• Myocarditis
• Pericarditis ( actually myopaericarditis if you wish to show off...pericardium is not electically active hene will have NO ECG changes and NO troponin rise!)

• It is raised in renal failure but do NOT use this as a differential until investigations are completed, renal failure patients can have uraemic pericarditis and can have ACS.