84 - Oral Communication
Diagnostic laboratory: Today & tomorrow
Feb. 26, 2021, 1:45 p.m. - 3:15 p.m., Sydney
A Comparison of Functional Methods with Absolute Quantification of Heparin Levels in Clinical Samples by Heparin Red Assay
E. Bontekoe1, F. Siddiqui1, D. Hoppensteadt1, A. Kouta1, J. Fareed1, R. Kraemer2, Presenter: E. Bontekoe1 (1Maywood, 2Heidelberg)
Background and Objective
Activated partial thromboplastin time (aPTT) method is widely used as a routine blood test and is commonly used for the monitoring of heparin levels in clinical patient samples. However, many endogenous factors contribute to observed prolongation of this test. Heparin Red assay utilizes fluorescence for the direct and sensitive detection of the absolute level of heparin in plasma. The purpose of this study is to compare functional activities (anticoagulant and anti-Xa levels) in clinical patient samples to the absolute levels of heparin to determine endogenous activity upon the therapeutic administration of this agent.
Plasma samples from patients treated with therapeutic dosage of heparin (n=100) were collected from Loyola University Medical Center. Citrated blood samples were analyzed using aPTT clotting method, anti-Xa chromogenic assay and Heparin Red (Redprobes UG, Deutschland) assay relative to a commercially used heparin (Medefil) calibration curves. Normal controls were comprised of commercially available 25 male and 25 female citrated plasma samples (George King Biomedical, Overland Park, Kansas City). Results were compiled as mean ± SEM and analyzed for significance and correlation.
Marked increases were noted in aPTT (81.11±7.37, normal 30.16±0.80 sec.; p<0.001), anti-Xa (43.90±2.83, normal 0±0 % Inhibition; p<0.001), and Heparin Red recovered concentration (2.90±0.16, normal 0.07±0.03 ug/ml; p<0.001) in clinical samples compared to normal controls. Although a large scatter in data in all of the assays was noted and shown in Figure 1, significant correlations were observed between Heparin Red and other functional parameters studied.
These studies demonstrate that Heparin Red method is a reliable assay for the absolute quantification of circulating heparin level in plasma. Unlike the functional methods, which are also influenced by many endogenous factors, such as AT levels and variations in the clotting proteins, Heparin Red detects absolute amounts of circulating heparin in plasma which are not influenced by endogenous factors and other anticoagulant drugs.