Sample collection time and sample handling are important for cardiac markers. Blood samples should be collected and assayed in intervals. ESC/ACC guidelines stress the importance of serial sampling. They recommend sampling at presentation of chest pain (baseline), then at 6 - 9 hours, and if these samples are negative and necrosis is still suspected, repeat samples at 12 - 24 hours. Some studies recommend sampling at presentation, 2 - 4 hours, 6 - 8 hours, and at 12 hours.
Many labs will have serial troponin testing orderable as a panel (baseline, 30 min, 1 hour, 2 hour, etc.)
Biomarker measurement should be available 24 hours a day and the results presented within 30 - 60 minutes after sample collection.
Point-of-care troponin testing is available and thus, whole blood samples can be used. Most large labs will also have plasma assays, which are thought to be more precise.
When using plasma, proper centrifugation is critical as small clots or debris are known to cause false-positive troponin results on some platforms. Once centrifuged, samples should be handled with care to avoid resuspension of any particulate matter that can interfere with the assay.