Naltrexone and Thyroid Function
Naltrexone does not appear to cause clinically significant thyroid dysfunction in patients with or without pre-existing thyroid disorders, and no specific thyroid monitoring is required when prescribing naltrexone for its approved indications of opioid or alcohol dependence.
Evidence for Lack of Thyroid Effects
The available evidence demonstrates minimal to no clinically relevant impact of naltrexone on thyroid function:
In former opioid addicts treated with naltrexone 50 mg daily for up to 14.5 months, all subjects remained euthyroid with normal TSH, total T4, and total T3 levels 1. While there was a positive correlation between duration of naltrexone use and T3 levels (r = +0.72, p < 0.001), all values remained within normal reference ranges 1.
A large quasi-experimental study of 898 patients with hypothyroidism found no association between starting low-dose naltrexone and subsequent changes in thyroid hormone requirements 2. If anything, there was a slight tendency toward increasing levothyroxine consumption with increasing LDN exposure, suggesting naltrexone does not improve thyroid function in hypothyroid patients 2.
A comprehensive review of psychotropic drug effects on thyroid function found that naltrexone has minor to no interference with thyroid functions 3. The review concluded that no specific thyroid monitoring recommendations are needed for patients receiving naltrexone 3.
Clinical Implications
For patients with pre-existing thyroid disorders:
- Naltrexone can be safely prescribed without concern for worsening thyroid function 1, 3.
- Continue standard thyroid hormone replacement therapy without adjustment based on naltrexone initiation 2.
- Routine thyroid function monitoring beyond standard care for the underlying thyroid condition is not necessary 3.
For patients without thyroid disorders:
- No baseline or follow-up thyroid function testing is required when initiating naltrexone 3.
- The primary monitoring concern with naltrexone is hepatotoxicity, requiring liver function tests at baseline and every 3-6 months 4, 5.
Important Caveats
The hepatotoxicity concern is more clinically relevant than thyroid effects:
- Naltrexone can cause hepatotoxicity at supratherapeutic doses, necessitating liver function monitoring 4, 5.
- Naltrexone should be avoided in patients with severe alcoholic liver disease or acute hepatitis 6.
- Given the potential for hepatotoxicity, naltrexone has not been extensively tested in patients with advanced liver disease 6.
Standard naltrexone prescribing considerations remain paramount: