Erythrocyte sedum ate rate

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Here is a thorough overview of the Erythrocyte Sedimentation Rate (ESR):

Erythrocyte Sedimentation Rate (ESR)

Definition

The ESR measures the distance (in mm) that red blood cells (RBCs) fall in a column of anticoagulated blood over 1 hour. It is one of the oldest laboratory tests still in clinical use and serves as a nonspecific marker of systemic inflammation.

Textbook of Family Medicine 9e, p. 230
Medical Physiology (Boron & Boulpaep)

Mechanism

When the body is stressed by infection, injury, or disease, the liver mounts an acute-phase response and releases proteins - especially fibrinogen - into the bloodstream. Fibrinogen (and other asymmetric plasma proteins) reduces the negative surface charge of RBCs (called the zeta potential), causing them to clump together in stacks called rouleaux. Rouleaux have a lower surface-area-to-volume ratio and sediment faster than individual cells.

Plasma proteins that accelerate ESR (in decreasing order of effect):

Fibrinogen
Beta (β-) globulins
Alpha (α-) globulins
Gamma (γ-) globulins

Albumin and lecithin retard sedimentation.

Three Stages of Sedimentation

Stage	Duration	What Happens
1	First 10 min	Rouleaux formation; little settling
2	Next ~40 min	Constant rate of settling
3	Final 10 min	Packing at tube bottom; rate slows

Henry's Clinical Diagnosis and Management by Laboratory Methods

Normal Reference Values

Population	Normal ESR
Neonates (0 to <1 month)	≤2 mm/hr
Children (1 month - 12 years)	≤20 mm/hr
Males >12 years	≤15 mm/hr
Females >12 years	≤20 mm/hr

Age-adjusted formula for adults:

Men: Age (years) ÷ 2
Women: (Age + 10) ÷ 2
Harriet Lane Handbook, 23rd ed.

Measurement Method: Westergren (Standard)

The Westergren method is the international reference standard (ICSH recommended). It uses:

A straight tube 30 cm long, 2.55 mm internal diameter, graduated 0-200 mm
Sodium citrate (0.105 mol/L) as anticoagulant-diluent
Blood diluted 4:1 (blood:citrate); the tube is read after exactly 1 hour

The patient's hematocrit should not exceed 35% for optimal reproducibility.

Factors That Alter ESR

Increase ESR	Decrease ESR	No Effect
Anemia	Polycythemia	Body temperature
Macrocytosis	Microcytosis	Recent meal
Female gender	Spherocytosis	Aspirin
Advanced age	Extreme leukocytosis	NSAIDs
2nd/3rd trimester pregnancy	Sickle cell disease	1st trimester pregnancy
Hypoalbuminemia	Excessive anticoagulant
Tilted ESR tube	Short ESR tube
High room temperature	Low room temperature / clotted sample

Textbook of Family Medicine 9e

Clinical Uses

Polymyalgia rheumatica (PMR) - ESR is typically markedly elevated; used for diagnosis and monitoring response to steroids
Temporal (giant cell) arteritis - 90% of biopsy-confirmed cases have ESR >30 mm/hr (mean ~90 mm/hr); ~4% have normal ESR
Monitoring chronic inflammatory diseases - e.g., rheumatoid arthritis, lupus (SLE)
Infection screening - elevated in bacterial infections, TB, endocarditis
Malignancy - markedly elevated ESR (>100 mm/hr) raises suspicion for myeloma, lymphoma
NOT recommended as a screening test in asymptomatic individuals - contributes to detection of serious illness in fewer than 6 per 10,000 asymptomatic patients

ESR vs. CRP - Key Comparison

Feature	ESR	CRP
Response speed	Slow (days)	Rapid (peaks 2-3 days)
Affected by age/sex	Yes (higher in women, elderly)	No
Affected by RBC morphology	Yes	No
Sensitivity in SLE flares	Good	Poor
Reflects single protein	No (multiple proteins)	Yes (single acute phase protein)
Stored sample usable	No (requires fresh blood)	Yes

Firestein & Kelley's Textbook of Rheumatology

Key Clinical Pearl

An extreme elevation (>100 mm/hr) almost always indicates serious underlying disease - most commonly multiple myeloma, malignancy, severe infection, or connective tissue disease. If no cause is apparent after history and examination, repeating the test in several months is preferred over an extensive hunt for occult disease.

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