skip to main content

BSR 2025 MCV Investigation Trigger — SCE Rheumatology MCQ

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

EasyRheumatoid ArthritisBSR 2025 MCV Investigation TriggerSCE Rheumatology

A 55-year-old woman with rheumatoid arthritis has taken methotrexate 20 mg weekly with folic acid for two years. She is clinically well with no symptoms of anaemia, infection or bleeding. Routine monitoring bloods show MCV 106 fL, haemoglobin 131 g/L, white cell count 6.8 x 10⁹/L, neutrophils 4.1 x 10⁹/L, platelets 265 x 10⁹/L, and normal liver and renal function. According to current UK csDMARD monitoring guidance, what is the most appropriate action?

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

Reveal the answer and explanation

Correct answer: D — Check vitamin B12, folate and thyroid function, and continue to monitor the MCV

Explanation lettering: E = shown as A · A = shown as B · D = shown as C · C = shown as D · B = shown as E

C is correct. UK csDMARD monitoring guidance (NHS SPS, aligned to the BSR csDMARD guideline; mirrored in NHS shared-care protocols) sets an MCV above 105 fL as the trigger to look for alternative, treatable causes of macrocytosis: check vitamin B12, folate and thyroid function, treat any abnormality, and continue MCV surveillance, discussing with the specialist team if results are normal. Methotrexate commonly causes mild macrocytosis, but at 106 fL a coexisting cause such as B12 deficiency or hypothyroidism must be excluded rather than assumed absent (D). Immediate cessation with urgent haematology referral (A) is reserved for significant cytopenias or warning symptoms such as severe sore throat or abnormal bruising, absent here with entirely normal counts. Checking folate alone with empirical folic acid escalation (B) would miss B12 deficiency and thyroid disease. No UK threshold of 120 fL exists (E).

Reference: NHS Specialist Pharmacy Service. Methotrexate monitoring (aligned to BSR 2025 csDMARD guideline): MCV >105 fL — check B12, folate and TSH; treat if abnormal, discuss with specialist team if normal. https://sps.nhs.uk/monitorings/methotrexate-monitoring/