From the Guidelines
Monitoring methotrexate requires regular laboratory testing, including full blood counts, liver function tests, and urea and electrolytes, which should be repeated every 7-14 days for the first month, and then every 2-3 months once the therapy has been stabilized. This is based on the guidelines from the British Association of Dermatologists, which recommend regular monitoring to prevent toxicity while ensuring therapeutic efficacy 1. The monitoring should include:
- Full blood counts (FBC) to check for myelosuppression
- Liver function tests (LFTs) to check for hepatotoxicity
- Urea and electrolytes (U&E) to check for nephrotoxicity
- Peptide of procollagen III (PIIINP) to check for liver fibrosis, which should be monitored at least every 3 months in patients with psoriasis
- Folic acid supplementation is also recommended to reduce side effects, with a strength of recommendation of A 1. Additionally, patients should be monitored for symptoms of toxicity, including mouth sores, rash, persistent cough, shortness of breath, nausea, vomiting, and unusual fatigue. It is also important to consider the patient's renal function, and reduction in methotrexate dosage should be considered in those with suboptimal renal function < 20 mL min^-1 1. The routine use of liver biopsy for monitoring methotrexate hepatotoxicity is not recommended, unless there are abnormal liver function tests or other risk factors for liver disease 1. Overall, the monitoring of methotrexate should be individualized based on the patient's risk factors, disease severity, and response to therapy.
From the FDA Drug Label
Patients undergoing methotrexate therapy should be closely monitored so that toxic effects are detected promptly. Baseline assessment should include a complete blood count with differential and platelet counts, hepatic enzymes, renal function tests and a chest X-ray During therapy of rheumatoid arthritis and psoriasis, monitoring of these parameters is recommended: hematology at least monthly, renal function and liver function every 1 to 2 months.
Monitoring of methotrexate should include:
- Baseline assessment: complete blood count, hepatic enzymes, renal function tests, and chest X-ray
- Regular monitoring:
- Hematology: at least monthly
- Renal function: every 1 to 2 months
- Liver function: every 1 to 2 months This monitoring is necessary to detect toxic effects promptly and to adjust the dose or discontinue the drug if necessary 2.
From the Research
Monitoring Methotrexate
- Methotrexate (MTX) is a commonly used drug for treating various conditions, including rheumatoid arthritis, and its monitoring is crucial to reduce toxicity and side effects 3.
- The drug is eliminated via the kidneys, and higher doses can produce toxicity, such as bone marrow suppression, pulmonary toxicity, nephrotoxicity, hematologic toxicity, and an increased risk of infections 3.
- Monitoring of MTX therapy includes:
- Liver blood tests (alanine aminotransferase [ALT], aspartate aminotransferase [AST], alkaline phosphatase, albumin, bilirubin) every 4-8 weeks 4.
- Complete blood cell count and serum creatinine tests prior to starting treatment with MTX 4.
- Hepatitis B and C serologic studies prior to starting treatment with MTX 4.
- Routine surveillance liver biopsies are not recommended for RA patients receiving traditional doses of MTX, but a biopsy should be performed if a patient develops persistent abnormalities on liver blood tests 4.
- In patients with renal deficiency, a lower initial dose is considered with an estimated glomerular filtration rate (eGFR) between 30 and 59 mL/minute, and these patients need to be monitored closely 3.
- MTX is contraindicated in patients with RA if the eGFR is <30 mL/minute 3.
- Folic acid is recommended as prophylaxis against specific side effects, such as myelosuppression, gastric toxicity, and neurotoxic effects 3, 5, 6.
- Laboratory monitoring in the context of MTX treatment is carried out less frequently than recommended in the literature, and potential MTX-associated serious complications are rare from a practice perspective 6.
- Guidelines for blood test monitoring of MTX toxicity in juvenile idiopathic arthritis suggest that routine blood tests every 4 to 8 weeks may be unnecessarily frequent 7.