Related Experiment Video
Updated: Sep 29, 2025

Diagonal Method to Measure Synergy Among Any Number of Drugs
Published on: June 21, 2018
Awareness of drug laboratory test interactions is important for prevention of unnecessary additional diagnostics: An
Jasmijn A van Balveren1, Lale Erdem-Eraslan2, Wilhelmine P H G Verboeket-van de Venne3
1Laboratory for Clinical Chemistry and Haematology, Jeroen Bosch Hospital, Henri Dunantstraat 1, 5223 GZ 's-Hertogenbosch, The Netherlands; Department of Health Technology and Services Research, Technical Medical Centre, University of Twente, Hallenweg 5, 7522 NH Enschede, The Netherlands.
Background:
Elevated levels of Chromogranin A (CgA) may be indicative of a neuroendocrine tumour (NET), but increased levels are also observed after intake of proton pump inhibitors (PPIs). The incidence of diagnostic confusion because of this drug-laboratory test interaction (DLTI) was examined.
Methods:
Medical records of 238 patients with elevated CgA concentrations were obtained from three hospitals. The following data were extracted: PPI prescription at the time of CgA measurement, medical decision making based on elevated CgA concentrations, final diagnosis, comorbidity and other prescribed drugs.
Results:
From 238 patients with elevated CgA concentrations, 132 used PPIs. Of these patients, 57 patients did not have a NET. In 9 of these 57 patients (16%), diagnostic work up revealed no medical cause of an elevated CgA concentration. Somatostatin receptor imaging was ordered in 4 out of 9 cases, with no abnormalities observed. In 6 out of 9 cases, CgA measurement was repeated after PPI discontinuation resulting in normalisation of CgA concentrations.
Conclusion:
In this retrospective patient record study we observed that part of the elevated CgA concentrations in patients could be caused by the usage of PPIs causing unnecessary diagnostic work-up for the exclusion of a NET. These observations illustrate the need for better DLTI awareness.
More Related Videos
Related Concept Videos
Combined Effects of Drugs: Synergism
Such synergistic combinations...
Factors Affecting Protein-Drug Binding: Drug Interactions
Displacement interactions can have varying outcomes, ranging from toxicity to virtually...
Drug Concentrations: Measurements
Plasma...
Agonism and Antagonism: Quantification
To quantify these effects, researchers use a dose-response curve, which provides valuable information about the potency and efficacy of a drug. Potency refers to...
Pharmacovigilance
This process, termed pharmacovigilance, aims to detect, evaluate, and minimize harmful effects related to medication use. The data collection for pharmacovigilance depends on spontaneous reporting systems, where healthcare professionals or patients voluntarily report suspected ADRs.
In some cases, there...
Acute Kidney Injury IV: Diagnostic Studies and Prevention

