Rifampicin Causes False-Positive Immunoassay Results for Urine Opiates
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Marta de Paula
Abstract
The treatment of tuberculosis usually includes the antibiotic rifampicin, especially in patients with concomitant human immunodeficiency virus infection. Some of these patients are in withdrawal therapy for drug abuse. When opiate screening is carried out in patients receiving rifampicin, false positive results are detected with the kinetic interaction of microparticles in solution method. We evaluated this interference in a Cobas-Integra analyzer and found a 12% cross-reactivity of rifampicin for antibiotic concentrations ranging from 0.19 to 6.08 μmol/l (156 to 5000 μg/l). This effect is not explained by the colour of the rifampicin solutions. Calculations assuming first order kinetics of elimination show that more than 18 hours after a single oral dose of 600 mg of rifampicin, a false positive result for opiates could be obtained. This indicates that the risk of a false positive result must always be considered when urine samples from these patients are analyzed.
Copyright © 1998 by Walter de Gruyter GmbH & Co. KG
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Articles in the same Issue
- The Biochemistry of Gene Therapy for AIDS
- Reticulocytes and Reticulated Platelets: Simultaneous Measurement in Whole Blood by Flow Cytometry
- Salivary Cortisol - an Alternative to Serum Cortisol Determinations in Dynamic Function Tests
- A Time-Resolved Fluorescence Immunoassay for the Measurement of Testosterone in Saliva: Monitoring of Testosterone Replacement Therapy with Testosterone Buciclate
- External Quality Assessment of Molecular Biology-Based Methods Used in Laboratories of Clinical Chemistry and Human Genetics
- Preoperative Values of Molecular Coagulation Markers Identify Patients at Low Risk for Intraoperative Haemostatic Disorders and Excessive Blood Loss
- Rifampicin Causes False-Positive Immunoassay Results for Urine Opiates
- Neuron-Specific Enolase: Reference Values in Cord Blood
- Additional Essential Criteria for Quality Systems of Medical Laboratories
- Low Concentration Monoclonal and Oligoclonal Bands in Serum and Urine Using the Sebia Hydragel Protein Electrophoresis System
