Kidney Disease and Cannabinoid Testing: Why Lower Urinary Excretion Can Accompany Higher Exposure
Patients with advanced chronic kidney disease can show greater cannabinoid exposure while excreting less of certain metabolites in urine. A clinical pharmacokinetic study demonstrates why urine results should not be treated as a direct gauge of circulating exposure.
What was compared?
Sønderskov and colleagues compared people with advanced kidney disease and controls after a single dose of a THC/CBD medicine. The study was nonrandomized and unblinded. Plasma concentrations, 24-hour urinary excretion, and reported side effects were assessed.
The measurements distinguished parent cannabinoids from hydroxylated, carboxylated, and glucuronidated metabolites. Those chemicals differ in activity and handling; grouping them into a single “THC level” obscures the question being tested.
Two directions of change
Total exposure to THC, CBD, and metabolites was higher in the kidney-disease groups, with substantial variability. Urinary excretion of THC-COOH and its glucuronide was lower. Dizziness was more pronounced in patients with kidney disease.
Not every association survived adjustment in the same way. The relationship between renal measures and THC exposure was no longer significant after adjustment for age, body mass index, and sex, whereas several other analyte relationships remained significant.
Limits of a single-dose comparison
The study measured total rather than free concentrations and followed a limited period after one dose. It did not establish accumulation during long-term treatment, symptom efficacy, or a validated individualized dose calculation. Groups were not fully matched on age and body composition.
For evidence interpretation, obtain renal history, the formulation and dose, specimen type, and sampling schedule. Lower urinary metabolite output cannot automatically mean less absorbed drug. Equally, a higher plasma exposure does not independently establish driving impairment or explain every reported symptom.
Related reading: why urine and blood results are not interchangeable.
Primary research
Marie Bach Sønderskov; Dinah Sherzad Khatir; Krista Dybtved Kjærgaard; Jørgen Bo Hasselstrøm; Lambert Kristiansen Sørensen; Eva Aggerholm Sædder; Charlotte Uggerhøj Andersen. Pharmacokinetics and Side Effects of Δ9-Tetrahydrocannabinol and Cannabidiol in Patients with Different Stages of CKD. Kidney International Reports (2024). DOI: 10.1016/j.ekir.2024.12.030.
