How often should liver function tests (LFTs) be checked in a patient on isotretinoin?

Liver Function Test Monitoring for Patients on Isotretinoin

Liver function tests (LFTs) should be checked at baseline, after 2 months of therapy, and then every 3 months thereafter for patients on isotretinoin. 1, 2

Monitoring Schedule

Initial Phase:

• Baseline LFTs before starting treatment
• Follow-up LFTs after 2 months of therapy

Maintenance Phase:

• Every 3 months for the duration of therapy

Laboratory Parameters to Monitor

The following should be included in LFT monitoring:

• Alanine aminotransferase (ALT)
• Aspartate aminotransferase (AST)
• Gamma-glutamyl transferase (GGT)
• Alkaline phosphatase
• Bilirubin

Evidence-Based Rationale

The most recent evidence from the American Academy of Dermatology indicates that routine monitoring after establishing baseline values and checking at 2 months is sufficient for most patients 1. This represents a shift from older recommendations that suggested more frequent monitoring.

The FDA drug label for isotretinoin recommends that "pretreatment and follow-up liver function tests should be performed at weekly or biweekly intervals until the response to isotretinoin has been established" 2. However, more recent studies have shown that significant hepatotoxicity is rare in otherwise healthy patients.

A 2016 study by the Journal of the American Academy of Dermatology found that elevated liver transaminases were detected infrequently (1.9%) and not significantly increased compared to baseline rates (1.6%) 3. When abnormalities were detected, they occurred at a mean of 61.9 days (approximately 2 months) into treatment for alanine transaminitis.

Special Considerations

When to Increase Monitoring Frequency

• If abnormal results are obtained, increase to weekly monitoring 4
• Adjust isotretinoin dose according to LFT results
• Consider discontinuation if transaminases are elevated to three times their upper normal limit 4

High-Risk Patients

More frequent monitoring may be warranted for patients with:

• Pre-existing liver disease
• History of alcohol consumption
• Use of other hepatotoxic medications
• Abnormal baseline LFTs

Management of Abnormal Results

• For mild elevations (less than 3× upper limit of normal): Continue monitoring more frequently
• For moderate elevations (3× upper limit of normal): Consider dose reduction and weekly monitoring
• For severe elevations (bilirubin > 50 μmol/L or ALT > 200 IU/L): Discontinue isotretinoin and refer to gastroenterology 4

Common Pitfalls to Avoid

1. Overmonitoring: Routine CBC monitoring is unnecessary and adds cost without clinical benefit 1, 3
2. Undermonitoring: Failing to check lipid panels and LFTs can miss significant abnormalities in up to 25% of patients 1
3. Ignoring clinical symptoms: Laboratory monitoring should be supplemented with assessment for symptoms of hepatotoxicity (jaundice, right upper quadrant pain, fatigue)

Recent evidence suggests that laboratory monitoring may be less necessary than previously thought in healthy young patients 5, but the current standard of care still recommends the monitoring schedule outlined above to ensure patient safety while on isotretinoin therapy.