Evaluation of the Activated Partial Thrombo-plastin Time (APTT) Sensitivity to Heparin Using Five Commercial Reagents: Implications for Therapeutic Monitoring
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Franco Manzato
Abstract
Heparin is an effective drug for prevention and treatment of thromboembolic conditions. Although several biological assays have been proposed for monitoring unfractionated heparin therapy, the measurement of the activated partial thromboplastin time (APTT) is the most widely employed test, and the overall risk of thromboembolic episodes was markedly reduced by maintaining APTT ratios above 1.5. However, the adjustment of the heparin therapy on the basis of APTT presents several questions which are still unresolved. Major discrepancies were found in APTTs performed using different reagents in both ex vivo and in vitro heparinized samples and occasionally with different lots of the same reagents; poor correlation was observed between APTT values and plasma heparin concentrations. In order to gain further insights into this phenomenon, we analysed the sensitivity to heparin of five commercial reagents for APTT measurement in 19 ex vivo heparinized samples. Differences were observed; correlation coefficients ranged from 0.820 to 0.985 and slopes of linear regressions from 0.26 to 1.14. Moreover, unsatisfactory correlations were obtained when APTT ratios were compared with heparin plasma concentrations in the same patients' samples. In the heparin therapeutic range of 0.35–0.70 U/ml, reagent-dependent differences were observed in the corresponding APTT values. These results point out a critical role of the assay methodology in monitoring heparin therapy by APTT. We suggest that reference materials and methods should be urgently identified, a universally agreed scale for reporting results should be established and reference ranges for the unfractionated heparin therapy should be reconsidered taking on account the reagent employed.
Copyright © 1999 by Walter de Gruyter GmbH & Co. KG
Artikel in diesem Heft
- Author Index
- Contents
- Subject Index
- Polymorphisms of Coagulation Factor Genes a Review
- Urinalysis-Challenges by New Medical Needs and Advanced Technologies
- The Automation of Sediment Urinalysis Using a New Urine Flow Cytometer (UF-100™)
- Urinary Microscopy as Seen by Nephrologists
- Measurement of Urine Relative Density Using Refractometer and Reagent Strips
- Dry Chemistry Urinalysis of Pathological Proteinuria
- Physiopathology of Proteinuria and Laboratory Diagnostic Strategy Based on Single Protein Analysis
- Microalbuminuria in Diabetes
- European Multicentre Evaluation of the Super Aution SA-4220 Urinalysis Analyser
- Optimized Detection of DNA Point Mutations by Double Gradient Denaturing Gradient Gel
- Is the Association of Serum Lipase with β2-Microglobulin or C-Reactive Protein Useful for Establishing the Diagnosis and Prognosis of Patients with Acute Pancreatitis?
- Analytical and Clinical Performance of an Automated Immunoassay System (Immulite®) for Estradiol in Serum
- Evaluation of the Activated Partial Thrombo-plastin Time (APTT) Sensitivity to Heparin Using Five Commercial Reagents: Implications for Therapeutic Monitoring
- An Alternative Analysis for Crossover Studies that Accounts for Between-Group Disparities in Drug Response
Artikel in diesem Heft
- Author Index
- Contents
- Subject Index
- Polymorphisms of Coagulation Factor Genes a Review
- Urinalysis-Challenges by New Medical Needs and Advanced Technologies
- The Automation of Sediment Urinalysis Using a New Urine Flow Cytometer (UF-100™)
- Urinary Microscopy as Seen by Nephrologists
- Measurement of Urine Relative Density Using Refractometer and Reagent Strips
- Dry Chemistry Urinalysis of Pathological Proteinuria
- Physiopathology of Proteinuria and Laboratory Diagnostic Strategy Based on Single Protein Analysis
- Microalbuminuria in Diabetes
- European Multicentre Evaluation of the Super Aution SA-4220 Urinalysis Analyser
- Optimized Detection of DNA Point Mutations by Double Gradient Denaturing Gradient Gel
- Is the Association of Serum Lipase with β2-Microglobulin or C-Reactive Protein Useful for Establishing the Diagnosis and Prognosis of Patients with Acute Pancreatitis?
- Analytical and Clinical Performance of an Automated Immunoassay System (Immulite®) for Estradiol in Serum
- Evaluation of the Activated Partial Thrombo-plastin Time (APTT) Sensitivity to Heparin Using Five Commercial Reagents: Implications for Therapeutic Monitoring
- An Alternative Analysis for Crossover Studies that Accounts for Between-Group Disparities in Drug Response
