skip to main content

DMF – Grade 3 Lymphopenia Stop Rule — SCE Neurology MCQ

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

ModerateMultiple Sclerosis & CNS InflammationDMF – Grade 3 Lymphopenia Stop RuleSCE Neurology

A 45-year-old woman with known MS has a stable EDSS of 3.0. She is on dimethyl fumarate. Her absolute lymphocyte count has been persistently below 0.5 × 10⁹/L for 6 months (grade 3 lymphopenia). What is the recommended action?

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

Reveal the answer and explanation

Correct answer: E — Stop DMF — persistent grade 3 lymphopenia (absolute lymphocyte count <0.5 × 10⁹/L for >6 months) on DMF increases the risk of PML and is an indication to discontinue

DMF commonly causes lymphopenia (~5–8% develop grade 3 lymphopenia — ALC <0.5). Persistent grade 3 lymphopenia (>6 months) is associated with increased PML risk. The SmPC and NICE TA320 recommend: (1) monitor ALC every 3 months, (2) if ALC <0.5 persists for >6 months, stop DMF. After discontinuation, lymphocyte counts typically recover over 4–6 weeks. Switch to an alternative DMT that does not cause lymphopenia or that has a different immune mechanism. A: Continuing increases PML risk. C: Dose reduction is not the standard recommendation. D: Antibiotics do not address the PML risk. E: Steroids are not a substitute DMT.

Reference: NICE TA320 DMF; DMF SmPC; ABN MS Guidelines