AST Monitoring Frequency for Patients on Methotrexate

Initial Monitoring Period

The American College of Rheumatology recommends that AST (with or without ALT), creatinine, and complete blood count (CBC) should be checked every 1-1.5 months during the initial period of methotrexate therapy or when increasing the dose 1, 2
The European League Against Rheumatism suggests that this more frequent initial monitoring is critical as the incidence of abnormal liver enzymes is higher in the first months of methotrexate therapy 2
After a stable dose is established, the monitoring frequency can be decreased to every 1-3 months, as recommended by the American College of Rheumatology 1, 2
For patients with dose increases, more frequent monitoring is suggested for 4-6 weeks after the change, as pancytopenia may occur during this period, according to the American Academy of Dermatology 3

The American Academy of Dermatology recommends that for patients with no risk factors for hepatotoxicity, monitor liver function tests monthly for the first 6 months and then every 1-3 months thereafter 3
Clinical assessment for side effects and risk factors should be performed at each visit, as suggested by the European League Against Rheumatism 2
Two observational studies showed an optimal interval for identifying abnormal liver enzymes of 30-60 days, according to the American College of Rheumatology 2

For elevations less than 2-fold upper limit of normal (ULN): repeat in 2-4 weeks, as recommended by the American Academy of Dermatology 3
For elevations ≥2-fold but <3-fold ULN: closely monitor, repeat in 2-4 weeks, and decrease dose as needed, according to the American Academy of Dermatology 3
For confirmed increase in AST greater than 3 times ULN: methotrexate should be stopped but may be reinstituted at a lower dose following normalization, as suggested by the American College of Rheumatology 1, 2

Patients with risk factors for hepatotoxicity may require more frequent monitoring, according to the American Academy of Dermatology 3
Risk factors include: history of alcohol consumption 3, obesity (BMI > 30) 4, diabetes mellitus 4, hyperlipidemia 3, family history of liver disease 3, advanced age 3, and renal impairment 4

The mean AST and percentage of elevated AST correlate with histological grades of liver disease in rheumatoid arthritis, as reported by the European League Against Rheumatism 2
Cumulative incidence of abnormal ALT/AST was reported as 48.9% above ULN and 16.8% above two ULN after a mean of 3.3 years on methotrexate, according to the American College of Rheumatology 2
Methotrexate-induced serious fibrosis and cirrhosis are rare, especially in rheumatoid arthritis patients, as suggested by the European League Against Rheumatism 2

During hospitalization for acute illness or infection, methotrexate should be temporarily discontinued and liver function tests monitored closely, as recommended by the American College of Rheumatology 6
When resuming methotrexate after prolonged discontinuation, consider more frequent monitoring initially, according to the European League Against Rheumatism 6
For patients undergoing elective orthopedic surgery, methotrexate can be safely continued with standard monitoring, as suggested by the American College of Rheumatology 6