Determination of 97.5th and 99th percentile upper reference limits for heart-type fatty acid-binding protein (H-FABP) in a US population.

Background: Heart-type fatty acid binding protein (H-FABP), a low molecular weight protein found primarily in myocardial tissue, has been identified as a potential biomarker in the detection of acute coronary syndrome and acute kidney injury. To further investigate clinical utility, we sought to establish an upper reference limit (URL) of H-FABP within a healthy U.S.
Methods: Serum samples of healthy donors were acquired from the AACC Universal Sample Bank. We analyzed 355 samples for H-FABP concentration using the Randox Laboratories immunoturbidimetric assay on the Roche Cobas 8000 series analyzer.
Results: The final sample population consisted of individuals aged 18-74 y, with 170 males and 185 females. The distribution of the population exhibited a strong positive skew, affecting outlier analysis and URL determination. The 97.5th-percentile URL was found to be 7.4 ng/ml (95% CI: 6.3-9.2), while the 99th-percentile URL was 12.1 ng/ml (8.6-14.9).
Conclusion: As the URL for H-FABP is highly affected by population distribution and outlier removal, final determination for an assay cutoff should be made in the context of clinical utility, either as a standalone assay or in conjunction with other biomarkers, and the desired clinical sensitivity and specificity.
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