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Difficulty: MediumMonitoring and Treatment Evaluation

A 41-year-old woman is evaluated in the rheumatology clinic for a follow-up visit. Two weeks ago, she was diagnosed with highly active, seropositive rheumatoid arthritis after presenting with persistent symmetric polyarthritis of her wrists, metacarpophalangeal, and proximal interphalangeal joints. She has no other medical conditions and takes no medications other than ibuprofen as needed. Physical examination shows active synovitis in both hands. Recent laboratory studies from her initial diagnostic workup demonstrate a normal complete blood count, normal comprehensive metabolic panel, positive rheumatoid factor, and positive anti-cyclic citrullinated peptide antibodies. After a discussion of treatment goals, the physician and patient agree to initiate systemic therapy with once-weekly oral methotrexate and daily folic acid supplementation. Which of the following additional tests must be obtained to establish safety baselines and rule out absolute contraindications prior to initiating this specific pharmacotherapy? (Select 2)

  1. Urine human chorionic gonadotropin levelAnswer
  2. Hepatitis B and C serologic panelAnswer
  3. C
    Thiopurine methyltransferase (TPMT) phenotype testing
  4. D
    Transthoracic echocardiography
  5. E
    Prothrombin time and international normalized ratio

Answer

The necessary baseline tests prior to initiating methotrexate in this patient include a urine human chorionic gonadotropin level and a Hepatitis B and C serologic panel.
Methotrexate is an immunosuppressive folate antimetabolite with a specific toxicity profile requiring rigorous baseline evaluation. It is highly teratogenic (an abortifacient) and is absolutely contraindicated in pregnancy; therefore, a human chorionic gonadotropin (hCG) level must be obtained in all women of childbearing potential before initiation. Furthermore, methotrexate carries a high risk of cumulative hepatotoxicity and can cause severe or fatal reactivation of chronic viral hepatitis. Because of this immunosuppressive risk, baseline screening with a Hepatitis B and C serologic panel is universally mandatory according to current rheumatology guidelines.

Step-by-Step Solution

1
Analyze the clinical scenario and proposed pharmacotherapy.
The patient is a 41-year-old female of childbearing potential who will be started on methotrexate for newly diagnosed rheumatoid arthritis.
Identifying patient demographics and the specific drug helps determine the required baseline safety monitoring protocols.
2
Evaluate the specific toxicity profile of the chosen medication.
Methotrexate is a folate antimetabolite known for severe teratogenicity, hepatotoxicity, pulmonary toxicity, and myelosuppression.
Understanding the adverse effect profile dictates which organ systems and contraindications require baseline laboratory evaluation.
3
Select the appropriate screening tests from the provided choices based on the established safety requirements.
A pregnancy test (hCG) is required due to teratogenicity, and a hepatitis panel is required to prevent reactivation of latent liver disease. TPMT, echocardiography, and PT/INR are not indicated for methotrexate.
Ensuring patient safety requires matching the baseline diagnostic workup directly to the known risks of the immunosuppressive agent.

Key Concept

Baseline safety monitoring for methotrexate therapy requires evaluating for pregnancy (in women of childbearing potential), chronic viral hepatitis, baseline cytopenias, and renal impairment.
Estimated Time:1m 30s
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Topics

Monitoring and Treatment Evaluation

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