RheumatologyTier 2Topic

Laboratory tests - erythrocyte sedimentation rate

Role

ESR is a non-specific marker of systemic inflammation in rheumatology, used alongside CRP to assess disease activity in inflammatory arthritis and vasculitis, and with a specific, well-defined diagnostic role in giant cell arteritis and polymyalgia rheumatica
Widely used given its low cost and long track record, though CRP has generally overtaken it as the preferred acute-phase marker for tracking rapid change given its faster kinetics

Principle

ESR indirectly reflects plasma protein (particularly fibrinogen) changes that promote red cell rouleaux formation and faster sedimentation - rises and falls more slowly than CRP, and is confounded by non-inflammatory factors (age, anaemia, pregnancy, obesity all independently raise ESR)

Uses

Markedly elevated ESR (often >50-100mm/hr) is a supportive diagnostic feature of giant cell arteritis and polymyalgia rheumatica, incorporated into diagnostic/classification approaches for both conditions
Used alongside CRP for disease activity monitoring in RA (incorporated into composite disease activity scores such as DAS28) and other inflammatory arthritides, and for monitoring vasculitis activity

Interpretation

Trend over time (not a single value) generally guides treatment decisions in chronic inflammatory rheumatic disease, given ESR's non-specificity and the confounding factors that affect any single measurement
A discordantly normal ESR/CRP despite apparent clinical disease activity, or vice versa, should prompt reconsideration of the clinical picture rather than over-relying on the numeric result alone

Associations

Giant cell arteritis/polymyalgia rheumatica (diagnostic use), rheumatoid arthritis disease activity scoring (DAS28), vasculitis activity monitoring

Kinetics

ESR's slower kinetics compared with CRP mean it lags behind rapid clinical change - CRP is generally preferred when tracking acute response to treatment, while ESR retains particular diagnostic value in the specific context of suspected GCA/PMR

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