Evaluation of immunochromatography-
based urine drug screening and blood drug

concentrations in suspected acute poisoning:
insights into negative urine drug screening
results

Evaluation of immunochromatography-
based urine drug screening and blood drug

concentrations in suspected acute poisoning:
insights into negative urine drug screening
results

Antipsychotic agents, Benzodiazepines, Drug evaluation, Chromatography

Abstract
Background Immunochromatography-based urine drug screening (UDS) can have false-positive or false-negative
results; thus, interpretation of results requires careful evaluation. A UDS-negative result simply indicates that target
drugs were not detected in urine and does not rule out acute poisoning. This study aimed to determine the presence
of drugs in the blood and blood drug concentrations in suspected cases of acute poisoning with UDS-negative
results.
Methods In this single-center, retrospective, observational study, we included 501 patients who attended Tokai
University Hospital Advanced Emergency Medical Center, Japan, between January 1, 2014 and December 31, 2023
and were diagnosed with acute poisoning with negative UDS results. The primary outcome included the detection
rate of UDS items and non-UDS items in blood samples. The secondary outcome included the classification of blood
drug concentrations (below therapeutic range, within therapeutic range, above therapeutic range). Blood drug
concentrations were measured using a gas chromatography–mass spectrometer and liquid chromatography–tandem
mass spectrometer.
Results Blood drug concentrations were detected in 498 (99.4%) of the 501 participants. Despite negative UDS
results in urine, UDS items were detected in blood samples of 239 patients (58.8%). Non-UDS items were detected in
430 participants (86.3%). Benzodiazepines were the most commonly detected UDS items, with many cases exhibiting
blood drug concentrations above the therapeutic range. In non-UDS items, non-benzodiazepine hypnotics,
antipsychotics, and over-the-counter (OTC) medications were often detected.
Conclusion This study demonstrates that negative UDS results do not rule out the presence of drugs in acute
poisoning cases. Moreover, a comprehensive evaluation, including physical and laboratory findings, is essential for
accurate diagnosis and treatment.

Rie Yamamoto1*, Yukari Maki1

, Yuri Iketani1

, Tomoatsu Tsuji1

, Takeshi Saito1

and Seiji Morita1

https://doi.org/10.1186/s12245-026-01119-y

2026

peri irawan

pdf

english

text