skip to main content

uPCR in Lupus Nephritis — SCE Rheumatology MCQ

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

ModerateSLE & Antiphospholipid SyndromeuPCR in Lupus NephritisSCE Rheumatology

A 50-year-old woman with systemic lupus erythematosus and lupus nephritis has a spot urine protein-to-creatinine ratio (uPCR) of 80 mg/mmol. Which option correctly states its approximate 24-hour protein equivalent and the proteinuria threshold in the 2019 EULAR/ACR SLE classification criteria?

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

Reveal the answer and explanation

Correct answer: E — Approximately 0.8 g/24 hours; threshold >0.5 g/24 hours or equivalent uPCR

Option E is correct. A spot uPCR provides an approximate estimate of daily protein excretion: UK equivalence tables relate 50 mg/mmol to about 0.5 g/day and 100 mg/mmol to about 1 g/day, so 80 mg/mmol is approximately 0.8 g/24 hours. This is an estimate rather than an exact conversion because daily creatinine excretion varies. In the 2019 EULAR/ACR SLE classification criteria, proteinuria greater than 0.5 g/24 hours, or an equivalent spot uPCR, contributes 4 points in the renal domain. Values of 0.08 or 8 g/day represent tenfold conversion errors, while 1 g/day is not the classification threshold. Spot uPCR is valid for lupus nephritis monitoring; 24-hour urine collection is not mandatory.

Reference: Aringer M et al. 2019 European League Against Rheumatism/American College of Rheumatology Classification Criteria for Systemic Lupus Erythematosus, renal-domain definitions, 2019. https://pubmed.ncbi.nlm.nih.gov/31385462/