Table 2. Median (range) maximal concentrations in 14 frequent and 10 occasional cannabis smokers following a single smoked 6.8% THC cigarette.
ParameterAnalyteFrequent smokersOccasional smokersTest statistic, UEffect size, rExact significance, 2-tailed (p)
Predose maximal concentration, μg/LTHCCOOHa14.2 (3.0–47.6)00−0.868<0.001
THC-glucuronidea,b10.0 (2.4–47.5)0 (0–8.2)6.0−0.779<0.001
THCCOOH-glucuronidea496 (272–1660)0 (0–34.8)0−0.843<0.001
Total THCCOOHa,c343 (189–1112)0 (0–23.0)0−0.843<0.001
Predose maximal concentration (creatinine normalized), μg/gTHCCOOHa7.6 (1.6–30.8)00−0.869<0.001
THC-glucuronidea,b8.1 (1.4–29.7)0 (0–6.5)6.0−0.779<0.001
THCCOOH-glucuronidea296 (119–949)0 (0–34)0−0.843<0.001
Total THCCOOHa206 (80.1–640)0 (0–22.3)0−0.843<0.001
Postdose maximal concentration, μg/LTHCCOOHa9.2 (3.5–36.6)1.5 (0–4.8)6−0.766<0.001
THC-glucuronidea,b15.0 (6.3–45.2)8.9 (1.3–21.5)30.5−0.437<0.05
THCCOOH-glucuronidea338 (147–2080)74.2 (8.7–214)4−0.789<0.001
Total THCCOOHa233 (100–1413)50.1 (5.8–146)4−0.789<0.001
Postdose maximal concentration (creatinine normalized), μg/gTHCCOOHa5.4 (2.7–22.1)1.7 (0–5.9)9−0.731<0.001
THC-glucuronidea,b17.3 (7.2–121)15.2 (3.0–35.1)32−0.418<0.05
THCCOOH-glucuronidea254 (145–1174)67.3 (20.8–305)15−0.657<0.01
Total THCCOOHa183 (98.5–798)45.3 (13.8–202)23−0.562<0.01
  • a Significant differences between occasional and frequent smokers.

  • b Participant H excluded from calculation because urine first void after smoking was not collected.

  • c Total THCCOOH (molar sum of THCCOOH and THCCOOH-glucuronide, equivalent to total THCCOOH following hydrolysis).