ESR
The slow but sensitive inflammation screen — unique diagnostic weight at very high levels
One of medicine's oldest blood tests. Less specific than CRP, responds more slowly, stays elevated weeks after inflammation resolves — yet for multiple myeloma, giant cell arteritis, and TB, a very high ESR carries diagnostic weight that few other tests match.
ESR measures how quickly red blood cells settle in a vertical tube over one hour. Normally, RBCs carry negative surface charges (zeta potential) that keep them apart. In inflammation, fibrinogen and other large proteins neutralise this charge, causing RBCs to form stacks (rouleaux) that are denser and settle faster. A high ESR says something is wrong — it doesn't say where.
Reference Ranges
How clinicians interpret ESR (Erythrocyte Sedimentation Rate) results — from optimal to concerning.
⚠ Reference ranges vary by laboratory and assay. Always interpret your result in context of your laboratory's own reference intervals and your clinical presentation.
What raises ESR (Erythrocyte Sedimentation Rate)
Primary driver — fibrinogen coats RBCs promoting rouleaux. Any condition raising fibrinogen raises ESR.
Paraprotein (M-spike) is a powerful RBC aggregator — ESR > 100, often > 150 mm/hr, is the classic presentation.
ESR > 50 is an ACR diagnostic criterion for GCA. ESR > 100 is characteristic. Measure alongside CRP.
Fewer RBCs means less intercellular charge repulsion — anaemia falsely elevates ESR independent of inflammation.
Progressively rises through pregnancy due to increased fibrinogen — up to 70 mm/hr at term.
ESR rises with age. Women have consistently higher ESR than men of the same age — use age-adjusted formula.
What lowers ESR (Erythrocyte Sedimentation Rate)
Very high RBC creates more intercellular repulsion — ESR is paradoxically low in polycythaemia vera.
Sickled cells cannot form rouleaux — ESR characteristically low even during painful crises.
Suppressed fibrinogen and inflammatory proteins — ESR normalisation confirms treatment response.
Conditions this biomarker signals
When ESR (Erythrocyte Sedimentation Rate) is outside normal range, these are the most clinically significant possibilities.
ESR > 100 (often > 150) from paraprotein-mediated RBC aggregation. Requires serum protein electrophoresis to confirm.
ESR > 50 is a diagnostic criterion (ACR). Both CRP and ESR should be measured — CRP is more sensitive.
TB, endocarditis, osteomyelitis — persistent high ESR with slow-to-rise CRP is characteristic of subacute/chronic infection.
Component of DAS28-ESR composite score. Correlates with synovial inflammation and radiographic progression.
Which tests measure this biomarker
ESR (Erythrocyte Sedimentation Rate) may be included in or ordered alongside these panels.
Always order alongside CRP — together they give different temporal information about inflammation.
Why rouleaux formation explains everything about ESR
Red blood cells carry a negative surface charge (zeta potential) that keeps them apart. Fibrinogen and large proteins in inflamed plasma neutralise this charge, allowing RBCs to stack into columns (rouleaux) that settle faster. The Westergren method measures settlement distance in a 200mm tube at exactly 60 minutes. While modest ESR elevation is non-specific, an ESR > 100 mm/hr has a short and serious differential — the three most common causes are infection (TB, endocarditis), malignancy (myeloma, lymphoma), and connective tissue disease (GCA, SLE, RA).
One of medicine's oldest tests
First described by Biernacki in 1897, standardised by Westergren in 1921. Despite 125 years of newer tests, ESR persists on hospital panels because its non-specificity is actually a useful feature — it tells you something is wrong without narrowing too early.
ESR and CRP measure different timescales
CRP is produced fresh in the liver within hours and falls within days of resolution. ESR reflects cumulative plasma protein changes — peaks 24–48h after CRP and remains elevated for weeks. Together they give temporal information: CRP = what's happening now; ESR = what's been happening for weeks.
A very high ESR has a short differential
Systematic reviews show ESR > 100 mm/hr has only three common underlying causes: infection, malignancy, and connective tissue disease. Approximately 5% of cases have no identifiable cause ("idiopathic") but these still require surveillance. A "very high ESR" should never be dismissed.
Clinical use — when and why this is ordered
How clinicians use ESR (Erythrocyte Sedimentation Rate) in practice — the real-world scenarios where it changes decisions.
GCA monitoring
Measured at baseline and 4-weekly during steroid taper. Rising ESR during taper precedes clinical relapse — early warning before symptoms return.
Myeloma screening
ESR > 100 with fatigue, bone pain, and hypercalcaemia triggers SPEP, Bence Jones protein, and bone marrow biopsy.
TB screening (low-resource settings)
ESR > 40 is a WHO TB screening criterion where laboratory infrastructure is limited.
RA / SLE disease activity
ESR part of DAS28-ESR composite score in RA; monitored alongside complement and anti-dsDNA in SLE.