Urinalysis Critical Vasculitis — SCE Rheumatology MCQ

Correct answer: D — They indicate glomerular inflammation, making renal vasculitis or another glomerulonephritis likely and requiring urgent renal assessment.

Dysmorphic erythrocytes and red cell casts localise haematuria to the glomerulus. In a patient with suspected small-vessel vasculitis, this active urinary sediment strongly suggests glomerulonephritis and therefore potentially organ-threatening renal vasculitis requiring urgent renal investigation and specialist assessment. Red cell casts are highly specific for glomerular bleeding, although they should not be described as absolutely pathognomonic for vasculitis. A lower urinary tract infection more typically produces pyuria and bacteriuria rather than dysmorphic cells or red cell casts. Nephrotic syndrome requires quantified heavy proteinuria and associated clinical or biochemical features. Nonglomerular bleeding produces predominantly isomorphic erythrocytes. Serum creatinine is important but does not replace urinalysis, which can reveal glomerular injury requiring prompt action.

Reference: National Institute for Health and Care Excellence. Acute kidney injury: prevention, detection and management, NG148, recommendations 1.4.2–1.4.3 and 1.5.15. Updated 2024. https://www.nice.org.uk/guidance/ng148/chapter/Recommendations