Association between thyroidea function and opioid agonist therapy: a prospective cohort study from Norway

Opioid agonist therapy (OAT) is an essential treatment for opioid dependency. However, OAT may lead to endocrinopathy, which may impair the tolerability of treatment. Although the risk of disturbed regulation of the adrenal and gonadal axes has been extensively studied, less is known about how long-term opioid use and corresponding risk factors influence the thyroid axis. The objective of this study was to investigate associations between biomarkers of thyroid function and OAT medication as well as sociodemographic and clinical factors and concurrent use of illicit substances among patients receiving OAT.

We used prospective data from 320 people receiving OAT in Bergen, Norway, from 2016 through 2023. All had 2 health assessments, including serum measurements of TSH. Descriptive statistics and a linear mixed model with coefficient and 95% CIs were performed to investigate the association between serum TSH (measured in mIU/L) and OAT medication as well as age, sex, substance use patterns, injecting use, housing status, and educational attainment at first assessment and over time.

Median serum TSH at first assessment in the study population was 1.8 mIU/L (interquartile range: 1.2). No association between OAT medications, sociodemographic, or clinical factors and serum TSH was found at first assessment and over time.

The median serum TSH was within the recommended range among people receiving OAT. No association between OAT treatment and thyroid insufficiency was found. This indicates that screening for thyroid function beyond symptomatic assessment is probably not needed among patients receiving OAT.