Scalp hair testing can report cannabinoid concentrations, but a separate question is whether those concentrations distinguish people with a particular clinical condition. Albert and colleagues compared hair samples from emergency department patients with cannabis hyperemesis syndrome with samples from two control groups.
The team obtained satisfactory hair samples from 46 people with positive urine tests, including 16 cases. Median hair THC was 220 picograms per milligram in the cases, 150 in recreational users without vomiting and 270 in emergency department controls. The ranges between the first and third quartiles overlapped. Hair CBD was often below the quantifiable range.
The authors observed a difference in the THC-to-CBN ratio between cases and recreational controls, but that group comparison did not validate a cutoff for classifying individual patients. The study illustrates why the concentration on a hair report and the clinical history need to be evaluated separately before drawing conclusions about vomiting episodes.