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Metamizole (dipyrone) as an interferent in biochemical assays
David Ceacero-Marín1, Lídia Martínez-Zamorano1, Adrían Gisbert-Alonso1
1Biochemistry Core of the Clinical Laboratory, Bellvitge University Hospital, Barcelona, Spain.
Abstract:
BackgroundMetamizole (MMZ), commonly used as an analgesic/antipyretic in countries like Spain, faces restrictions elsewhere due to side effects. Despite this, its frequent use underscores the critical importance of studying its impact on the accuracy of laboratory tests, particularly when blood samples are obtained shortly after intravenous administration.MethodsTo investigate the in vitro interfering effect of MMZ, 20 serum biochemical assays were selected. The concentrations of biochemical assays were measured in a serum pool spiked with increasing MMZ concentrations. For each assay, the percentage of interference was calculated and compared with our laboratory's quality requirements for bias.ResultsIn vitro interference was observed in some biochemical assays: cholesterol (CHOL), creatinine (CREA), high-density lipoprotein cholesterol (HDL), lactate (LAC), lactate dehydrogenase (LDH), triglycerides (TG) and uric acid (UA), leading to falsely reduced results. All of them, except for the LDH assay, exhibited clinically significant interference with CREA being the first to be affected at a metamizole concentration of 0.31 g/L. No interference was observed in the remaining assays.ConclusionsFalsely decreased and clinically significant CHOL, CREA, HDL, LAC, TG and UA results were observed in serum samples due to in vitro interference caused by MMZ contamination. Serum concentrations in patients receiving intravenous MMZ treatment may be falsely decreased due to interference by MMZ. Knowledge of such interferences in clinical laboratories is crucial for the correct diagnosis and treatment of patients.
Insights
Metamizole (MMZ) can interfere with lab tests, causing falsely low results for cholesterol, creatinine, HDL, lactate, triglycerides, and uric acid. This interference is clinically significant and impacts patient diagnosis and treatment.
Area of Science:
- Clinical Chemistry
- Laboratory Medicine
- Pharmacology
Background:
- Metamizole (MMZ) is a widely used analgesic and antipyretic, despite regulatory restrictions in some regions due to adverse effects.
- Its frequent clinical application necessitates an understanding of its potential impact on laboratory test accuracy, especially with intravenous administration.
Purpose of the Study:
- To evaluate the in vitro interfering effects of Metamizole (MMZ) on common serum biochemical assays.
- To determine the clinical significance of observed interferences based on laboratory quality requirements.
Main Methods:
- Twenty serum biochemical assays were selected for the study.
- Serum pools were spiked with varying concentrations of MMZ to assess in vitro interference.
- Interference levels were quantified and compared against established laboratory bias criteria.
Main Results:
- In vitro interference was detected in cholesterol (CHOL), creatinine (CREA), high-density lipoprotein cholesterol (HDL), lactate (LAC), triglycerides (TG), and uric acid (UA) assays, leading to falsely reduced values.
- Clinically significant interference was observed for all affected assays except lactate dehydrogenase (LDH).
- Creatinine (CREA) showed significant interference at a MMZ concentration as low as 0.31 g/L.
Conclusions:
- Metamizole (MMZ) contamination in serum samples can cause falsely decreased and clinically significant results for several key biochemical markers.
- These interferences may lead to inaccurate patient serum concentrations, potentially affecting diagnosis and treatment decisions.
- Awareness of MMZ-induced laboratory test interference is critical for accurate patient management in clinical settings.
