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Updated: Aug 6, 2026
11:06
Human Liver Microphysiological System for Assessing Drug-Induced Liver Toxicity In Vitro
Published on: January 31, 2022
Risk of significant liver enzyme elevation after switching antithyroid drugs
Rena Pollack1,2, Joshua Stokar1,2
1Department of Endocrinology and Metabolism, Hadassah Medical Center, Jerusalem, Israel.
European Journal of Endocrinology
|July 21, 2026
Summary
Switching antithyroid drugs (ATDs) like methimazole/carbimazole (MMI) or propylthiouracil (PTU) due to liver issues is common. Liver enzyme elevations occur frequently after switching, but rates are similar between MMI-to-PTU and PTU-to-MMI groups.
Area of Science:
- Endocrinology
- Hepatology
- Pharmacology
Background:
- Antithyroid drugs (ATDs) can cause clinically significant liver enzyme elevation.
- This adverse effect often requires treatment discontinuation and switching to an alternative ATD.
- Understanding the risks associated with switching ATDs is crucial for patient management.
Purpose of the Study:
- To investigate the incidence and patterns of liver enzyme elevation after switching between methimazole/carbimazole (MMI) and propylthiouracil (PTU).
- To compare the rates of significant liver injury between patients switching from MMI to PTU and those switching from PTU to MMI.
Main Methods:
- Retrospective cohort study using the TriNetX database.
- Included patients with hyperthyroidism who initiated MMI or PTU and developed significant liver enzyme elevation.
- Assessed outcomes for 120 days after switching to the alternate ATD.
Main Results:
- The cohort included 276 patients switching from MMI to PTU and 82 from PTU to MMI.
- Significant liver enzyme elevation occurred in 40% of MMI-to-PTU switchers and 30% of PTU-to-MMI switchers.
- Hepatocellular and cholestatic patterns of liver injury were observed at comparable rates across both switch groups.
Conclusions:
- Significant liver injury after switching ATDs is frequent but not inevitable.
- Liver injury rates are similar regardless of the direction of the switch (MMI to PTU or PTU to MMI).
- Close biochemical monitoring and individualized treatment decisions are essential for patients on ATDs.
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