skip to main content

Rheumatoid arthritis treated with methotrexate in chronic renal impairment — SCE Rheumatology MCQ

Instant feedback + full explanation. One question, done properly.

ModerateChronic Kidney DiseaseRheumatoid arthritis treated with methotrexate in chronic renal impairmentSCE Rheumatology

A 66-year-old woman with seropositive rheumatoid arthritis has maintained low disease activity for 18 months on subcutaneous methotrexate 20 mg once weekly and folic acid. She has chronic kidney disease attributed to diabetic nephropathy. Over 6 months, her eGFR has fallen from 76 to 43 mL/min/1.73 m² and has remained between 41 and 44 mL/min/1.73 m² for the subsequent 4 months. Cockcroft–Gault creatinine clearance is 46 mL/min. There is no dehydration, intercurrent illness or exposure to NSAIDs or trimethoprim. Full blood count and liver biochemistry are normal, and she has no mucositis or gastrointestinal symptoms. Which is the most appropriate methotrexate management strategy?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Reduce subcutaneous methotrexate to 10 mg weekly with increased monitoring

Explanation lettering: E = shown as A · A = shown as E

The decisive measurement is Cockcroft–Gault creatinine clearance, because the product information specifies renal dose adjustment using creatinine-clearance thresholds. Methotrexate is substantially eliminated by the kidneys, and impaired clearance increases exposure and the risk of delayed marrow, mucosal and gastrointestinal toxicity even when current laboratory results are normal. A creatinine clearance of 46 mL/min lies within the 30–59 mL/min band, for which the subcutaneous methotrexate dose should be 50% of the standard dose. Her current 20 mg weekly regimen should therefore be reduced to 10 mg weekly. Renal impairment also warrants closer monitoring, with subsequent review of rheumatoid arthritis activity because additional or alternative DMARD treatment may be needed if control deteriorates. A fails to account for reduced renal elimination. B is directionally plausible but 15 mg is 75% of the existing dose rather than the specified 50%. C is inappropriate because stable creatinine clearance below 60 mL/min requires dose reduction, not suspension until an arbitrary recovery threshold; her impairment is chronic and may not reverse. D would be appropriate if methotrexate were toxic, ineffective or contraindicated, but there is no current toxicity and a creatinine clearance above 30 mL/min permits adjusted treatment. Methotrexate must not be used when creatinine clearance is below 30 mL/min.

Reference: Metoject PEN solution for injection in pre-filled pen — Summary of Product Characteristics (Text revised 18 September 2024) — https://www.medicines.org.uk/emc/product/11358/smpc