Key result
PEG precipitation confirms macromolecular interference in an immunotherapy patient, reducing falsely elevated hs-cTnI by ~92%.
Why the study?
High-sensitivity cardiac troponin is susceptible to analytical interference leading to false-positive elevations, with macromolecular interferents known to cause this particularly in patients receiving immunotherapy.
Case Report (n=1)
Unexplained hs-cTnI elevations in immunotherapy-treated cancer patients should raise suspicion for macromolecular interference, which can be verified using PEG precipitation, dilution tests, and platform comparisons.
Clinicians should consider PEG testing for suspected interference in asymptomatic immunotherapy patients with elevated hs-cTnI; confirms mechanism in this setting but leaves broader prevalence open.
BACKGROUND: High-sensitivity cardiac troponin (hs-cTn) is crucial for diagnosing acute coronary syndrome but is susceptible to analytical interference, leading to false-positive elevations (FPE). Macromolecular interferents (e.g., heterophilic antibodies or macrocomplexes) are known causes, especially in immunocompromised patients, such as those receiving immunotherapy [1,2]. METHODS: A 62-year-old male with renal cell carcinoma on toripalimab presented with persistently elevated hs-cTnI levels without clinical signs of myocardial injury. Interference was assessed via polyethylene glycol (PEG) precipitation (using 25% PEG 6000), serial dilution, and alternative platform testing. PEG recovery < 20% indicated macromolecular interference. RESULTS: Initial hs-cTnI was 84.4 ng/mL (99th percentile URL = 24.2 ng/mL). Post-PEG, levels fell to 6.7 ng/mL (15.9% recovery), confirming interference. Serial dilution showed non-linearity. An alternate platform returned normal values. Subsequent hs-cTnI results remained normal, supporting transient interference. CONCLUSIONS: Unexplained hs-cTnI elevations in immunotherapy-treated cancer patients should raise suspicion for macromolecular interference. PEG precipitation, dilution tests, and platform comparisons are effective verifica-tion tools. Clinician-laboratory collaboration is key to preventing misdiagnosis.
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Luo et al. (2026) conducted a case report in False-positive hs-cTnI (n=1). Polyethylene glycol (PEG) precipitation was evaluated on hs-cTnI levels post-PEG precipitation. Polyethylene glycol precipitation confirmed macromolecular interference in a patient on immunotherapy, reducing falsely elevated hs-cTnI from 84.4 ng/mL to 6.7 ng/mL (15.9% recovery).
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