A false positive case of high-sensitivity cardiac troponin in a patient with acute chest pain: Analytical study of the interference

Falsely elevated type IV collagen caused in part by heterophilic antibodies: A case report

Immunoassays, which are used ubiquitously in clinical practice, are inherently vulnerable to distortions arising from endogenous immunoglobulins, particularly heterophilic antibodies. While many studies have explored interference in substances measured using chemiluminescence or electrochemiluminescence methods based on the double-antibody sandwich principle, there are limited data on interference in immunoturbidimetric assays, particularly for type IV collagen. This article presents the first report of a noteworthy increase in serum type IV collagen levels stemming from heterophilic antibody interference detected through an immunoturbidimetric assay. The present study investigated the mechanisms of this interference and the differences introduced by heterophilic antibodies between the two methodologies. Additionally, it outlines strategies for identifying and mitigating such interference, and discusses the principles, limitations, and considerations of each corrective approach. The objective is to raise awareness among clinical laboratory professionals concerning the potential interference of heterophilic antibodies in immunoturbidimetric assays. Increased awareness will aid in the prompt detection and correction of this issue, ensuring the provision of accurate and reliable laboratory data for informed clinical decision-making and the prevention of adverse medical outcomes.

Review of Literature and Recommended Procedures for Management of Unusual Cases of False Positive Troponin Tests

Heterophile antibodies are immunoglobulins produced by the immune system in response to exposure to animal and bacterial antigens, blood transfusions, autoimmune disorders, hematologic malignancies, dialysis, and pregnancy. Recently, these antibodies have garnered significant attention due to their impact on the accuracy of laboratory test results. Heterophile antibodies can bind not only to specific antigens but also to those from different species, including the antibodies used in laboratory tests. This cross-reactivity with foreign proteins is the basis for their interference in immunological assays, such as those measuring cardiospecific troponins (cTn). This manuscript reviews the literature on cases of heterophile antibody interference in troponin testing and proposes an algorithm for identifying such interference when clinical discrepancies arise. Recognizing and addressing heterophile antibody interference is crucial, particularly for tests like those for troponins, which are key biomarkers in the diagnosis and management of emergency and intensive care patients. The literature emphasizes the need for accurate procedures to distinguish true cardiac damage from false positives, thereby preventing unnecessary additional tests and hospitalizations.

Elevated cardiac troponin secondary to heterophile antibodies: a case series highlighting an underrecognized differential

Background

Heterophile antibody presence confounds troponin assay results, causing falsely elevated troponin levels. This rare phenomenon is an important differential to consider when evaluating patients with suspected acute coronary syndrome. We present a case series of three patients with similar clinical presentations where the presence of heterophile antibodies was confirmed.

Case summary

We reviewed three patients from our hospital who presented with chest pain in a 12-month period. All patients were males aged 50-70. All patients had elevated troponin, and there was clinical concern for acute coronary syndrome in two patients. Two patients underwent coronary angiography during admission, and the third had a recent angiogram within the last 6 months. No obstructive lesions were found, and no alternative diagnoses were identified. Ultimately, the presence of heterophile antibodies was confirmed in all three patients.

Discussion

Heterophile antibody presence is an important differential to consider in patients with unexplained troponin elevation. Once the presence of heterophile antibodies is confirmed, this aids in clinician decision-making and helps to guide investigations and treatment in future.

On the Effect of Heterophilic Antibodies on Serum Levels of Cardiac Troponins: A Brief Descriptive Review

Serum levels of cardiac troponins can be increased both with myocardial damage and in the absence of myocardial damage. In the second case, this is due to the influence of false-positive factors, among which heterophilic antibodies play a significant role. Understanding the causes of the formation of heterophilic antibodies, the features and mechanisms of their effect on serum levels of cardiac troponins, is an important condition for interpreting a false-positive result due to the influence of heterophilic antibodies. This brief, descriptive review presents the causes of heterophilic-antibodies formation and discusses their effect on serum levels of cardiac troponins.

Advances in 3D bioprinting technology for cardiac tissue engineering and regeneration

Cardiovascular disease is still one of the leading causes of death in the world, and heart transplantation is the current major treatment for end-stage cardiovascular diseases. However, because of the shortage of heart donors, new sources of cardiac regenerative medicine are greatly needed. The prominent development of tissue engineering using bioactive materials has creatively laid a direct promising foundation. Whereas, how to precisely pattern a cardiac structure with complete biological function still requires technological breakthroughs. Recently, the emerging three-dimensional (3D) bioprinting technology for tissue engineering has shown great advantages in generating micro-scale cardiac tissues, which has established its impressive potential as a novel foundation for cardiovascular regeneration. Whether 3D bioprinted hearts can replace traditional heart transplantation as a novel strategy for treating cardiovascular diseases in the future is a frontier issue. In this review article, we emphasize the current knowledge and future perspectives regarding available bioinks, bioprinting strategies and the latest outcome progress in cardiac 3D bioprinting to move this promising medical approach towards potential clinical implementation.

Discrepancy between Cardiac Troponin Assays Due to Endogenous Antibodies

BACKGROUND

Despite well-described analytical effects of autoantibodies against cardiac troponin (cTn) I on experimental assays, no study has systematically examined their impact on cTn assays in clinical use. We determined the effects of endogenous antibodies on 5 different cTnI assays and a cTnT assay.

METHODS

cTn was measured by 6 methods: Siemens hs-cTnI Centaur, Siemens hs-cTnI Vista, Abbott hs-cTnI Architect, Beckman hs-cTnI Access, Beckman cTnI Access, and Roche hs-cTnT Elecsys. Measurements were repeated on 5 assays (all except Siemens hs-cTnI Vista) following immunoglobulin depletion by incubation with protein A. Low recovery of cTnI (<40%) following immunoglobulin depletion was considered positive for macro-cTnI. Protein A findings were validated by gel filtration chromatography and polyethylene glycol precipitation.

RESULTS

In a sample of 223 specimens selected from a community laboratory that uses the Siemens hs-cTnI Centaur assay and from which cTn was requested, 76% of samples demonstrated increased cTnI (median, 88 ng/L; interquartile range, 62-204 ng/L). Macro-cTnI was observed in 123 (55%) of the 223 specimens. Comparisons of cTnI assays markedly improved once patients with macro-cTnI were removed. Passing-Bablok regression analysis between hs-cTnI assays demonstrated different slopes for patients with and without macro-cTnI. In patients with macro-cTnI, 89 (72%) showed no effect on the recovery of cTnT, whereas 34 (28%) had reduced recovery of cTnT. The proportion of results above the manufacturers' 99th percentile varied with the cTn assay and macro-cTnI status.

CONCLUSION

We suggest that the observed discrepancy between hs-cTnI assays may be attributed in part to the presence of macro-cTnI.

False-positive troponin I elevation in a newborn with neonatal encephalopathy

Serum biomarkers of myocardial damage are commonly used in babies after perinatal asphyxia. We present a case report of a persistently troponin I elevation without evidence of clinical or instrumental signs of myocardial ischaemia in a baby with perinatal asphyxia. When the blood was mixed with polyethylene glycol we found that the troponin I levels were falsely elevated due to interfering antibodies. This case shows that analytical errors may still occur despite modern immunoassay systems and underlines the need for further investigations to identify false-positive values in case of disagreement between clinical conditions and laboratory values.