Chronic Cannabis Abuse, Delta-9-tetrahydrocannabinol and Thyroid Function

Objective: The aim of this study was to obtain rather rare information about the influence of chronic cannabis abuse on thyroid function. Methods: Thyroid function tests (TSH, total T-3, free T-4) of 39 chronic cannabis-dependent subjects (ICD-10) were determined at admission (for in-patient detoxification). In a subgroup, serum levels of thyroid hormones were correlated with the serum levels of delta-9-tetrahydrocannabinol (THC, N = 24) and its major metabolites, THC-OH (N = 16) and THC-COOH (N = 24). Results: All of the tested patients were found to have TSH, total T-3 and free T-4 levels within the population reference range. The levels of thyroid hormones did not correlate significantly with levels of THC, THC-OH or THC-COOH in serum. Conclusion: These results argue against a relevant influence of chronic cannabis intake on thyroid function in humans.