Which of the following is a contraindication to methotrexate therapy?

• A. Hypertension
• B. Bone marrow suppression
• C. Hyperlipidemia
• D. Hyperthyroidism

Answer: (B)

Methotrexate acts as a folate antagonist that blocks DNA synthesis, hitting rapidly dividing cells hardest. The bone marrow is full of such cells, so MTX can cause or worsen cytopenias. If bone marrow is already suppressed, adding MTX can lead to severe anemia, leukopenia, and thrombocytopenia, raising the risk of serious infections and bleeding. That’s why bone marrow suppression is a contraindication to starting methotrexate.

The other conditions listed do not by themselves prevent MTX therapy. Hypertension, hyperlipidemia, and hyperthyroidism aren’t direct contraindications, though MTX requires monitoring for potential toxicity in patients with organ dysfunction or other risk factors.