# Tachycardia and Positive Amphetamine Screen are Associated With True Positive–Methamphetamine Exposures in Pediatric Patients

## TL;DR

This study finds that tachycardia and a positive amphetamine test are strong indicators of true methamphetamine exposure in children.

## Contribution

Identifies clinical factors that help distinguish true methamphetamine cases from false positives in pediatric patients.

## Key findings

- Tachycardia was present in 60% of patients and strongly associated with confirmed methamphetamine exposure.
- Amphetamine copositivity on UDS was seen in 50% of patients and 96% of these were confirmed methamphetamine positive.
- False-positive methamphetamine results on rapid UDSs were common in this pediatric cohort.

## Abstract

Methamphetamine exposure is a high-risk condition in pediatric patients. Standard screening often begins with a rapid urine drug screen (UDS) immunoassay, which can yield false-positive results. Confirmatory testing with gas chromatography and mass spectrometry is more accurate, but is not always readily available. This study aimed to identify clinical factors associated with true methamphetamine positivity.

We conducted a retrospective cohort study at a single children’s hospital, reviewing cases from January 1, 2018, to December 31, 2023. Patients with a positive screening test for methamphetamine, with results from confirmatory testing, were included. Demographic characteristics, laboratory values, urine findings, and clinical presentations were analyzed.

Of 205 patients with a positive UDS, 52 (25%) underwent confirmatory testing. Most were male (n = 28, 54%), and 33 patients (63%) were 0 to 5 years old. Confirmatory testing was positive for methamphetamine in 32 cases (62%). Tachycardia was present in 31 (60%) patients, and 26 (81%) of these were confirmed methamphetamine positive (P < .001). Amphetamine copositivity on the UDS was seen in 26 (50%) patients, 25 (96%) of whom were confirmed methamphetamine positive (P < .001). Hypokalemia, elevated creatine kinase level, elevated lactate level, and hyperthermia trended toward association, but did not reach statistical significance.

In this cohort, false–positive methamphetamine results on rapid UDSs were common. Tachycardia and concurrent amphetamine positivity were strongly associated with confirmed methamphetamine exposure. Clinicians should be aware of the limitations of immunoassay-based screening and consider confirmatory testing when available.