Mifepristone and Liver Function Tests
Baseline liver function tests (LFTs) should be obtained before initiating mifepristone, and the drug should not be used in patients with severe hepatic impairment; however, no specific routine monitoring schedule for LFTs is mandated in guidelines or FDA labeling for patients with normal baseline function.
Baseline Testing Requirements
Before starting mifepristone therapy, you must:
- Obtain baseline LFTs (AST, ALT, bilirubin) to identify pre-existing hepatic impairment
- Exclude severe hepatic impairment, which is an absolute contraindication 1
- Verify negative pregnancy test in females of reproductive potential 1
Dosing Adjustments Based on Hepatic Function
The FDA label provides clear guidance on hepatic impairment 1:
- Mild-to-moderate hepatic impairment: Maximum dose 600 mg once daily (half the standard maximum)
- Severe hepatic impairment: Do not use mifepristone
- Normal hepatic function: Standard dosing up to 1200 mg daily
Follow-Up Monitoring Considerations
Neither the 2021 Lancet Diabetes & Endocrinology guideline 2 nor the 2015 Endocrine Society guideline 3 specify routine LFT monitoring intervals for mifepristone. The guidelines emphasize that:
- Clinical parameters (glucose control, blood pressure, weight) guide dosing, not biochemical markers 3
- Thyroid function requires close monitoring 2
- Drug-drug interactions need careful review 2
Important Clinical Context
While routine scheduled LFT monitoring is not mandated, drug-induced liver injury (DILI) from mifepristone is documented but rare 4, 5. The reported cases show:
- Mixed hepatocellular/cholestatic pattern of injury 4
- Onset typically 1-3 months after initiation 4, 5
- Complete resolution after drug discontinuation 4, 5
- Symptoms include jaundice, pruritus, fatigue, and nausea 4
Interestingly, one case series demonstrated that mifepristone actually improved fatty liver disease and normalized liver enzymes in patients with hypercortisolism-related hepatic steatosis 6, suggesting the drug may have hepatoprotective effects in the context of excess cortisol.
Practical Monitoring Approach
Given the rare but documented hepatotoxicity risk, a reasonable clinical approach includes:
- Baseline LFTs (mandatory)
- Clinical vigilance for symptoms of liver injury (jaundice, pruritus, right upper quadrant pain, dark urine)
- Consider LFT monitoring at 1-3 months after initiation, when DILI risk appears highest based on case reports
- Immediate LFT assessment if any symptoms of hepatotoxicity develop
- No evidence supports routine ongoing monitoring beyond the initial period in asymptomatic patients with normal baseline function
Critical Pitfalls to Avoid
- Do not withhold mifepristone solely due to mildly elevated baseline LFTs in patients with Cushing's syndrome, as hypercortisolism itself causes metabolic liver disease that may improve with treatment 6
- Do not rely on cortisol levels to monitor treatment efficacy or adrenal insufficiency—mifepristone blocks the receptor, so cortisol levels remain elevated 2, 3
- Remember the maximum 600 mg daily dose in mild-to-moderate hepatic impairment 1