Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)

Pick Ordered or Not ordered to see the note.

Indicated when

• —Suspected inflammatory, infectious or rheumatologic disease: CRP is the preferred single marker of systemic inflammation [1]
• —ESR, added to CRP, only when the patient is age 50 or over with new shoulder or hip-girdle stiffness or constitutional symptoms (to assess for polymyalgia rheumatica, giant cell arteritis or myeloma), or suspected inflammatory arthritis or connective-tissue disease (AHC clinical direction, see evidence_notes)
• —CRP as part of the baseline rule-out panel for widespread pain meeting the clinical pattern for fibromyalgia, alongside CBC, creatine kinase and TSH; ESR only if one of the situations above applies [2, 1]

Not indicated when

• —Using ESR to screen asymptomatic patients, or as a general test to look for inflammation in a patient with an undiagnosed condition [1]
• —Adding ESR to the fibromyalgia rule-out panel when none of the ESR situations above applies
• —Ordering ESR and CRP together as a routine general inflammatory screen with no specific indication

Why not

ESR is a non-specific marker influenced by anemia, pregnancy and smoking, responds more slowly than CRP to a changing inflammatory process, and is vulnerable to technical error; Choosing Wisely Canada's Medical Biochemistry recommendation #2 advises against ESR to screen asymptomatic patients or as a general test for inflammation in undiagnosed conditions, and its backgrounder states that only CRP should be used as a measure of systemic inflammation [1].

Better first step

Order CRP alone where inflammation is a genuine concern, including in the fibromyalgia rule-out panel, and add ESR only when the patient is age 50 or over with new shoulder or hip-girdle stiffness or constitutional symptoms (to assess for polymyalgia rheumatica, giant cell arteritis or myeloma), or suspected inflammatory arthritis or connective-tissue disease [1].

Typical ND rationale

An ND may order ESR and CRP together as a general check for inflammation in a patient with widespread pain, fatigue, or vague symptoms, reasoning that the two markers together give a fuller picture of whether something inflammatory is going on.

Ontario coverage & CONO orderability

OHIP status

insured

Both components are listed by name in the 2026 Schedule of Benefits for Laboratory Services: sedimentation rate (L451) and C-reactive protein (L665). Both are insured when a physician who has clinically assessed the patient orders them. The same tests ordered by an ND are patient-paid regardless (Reg. 552 s.22).

CONO orderable

Yes — CONO list #47, #57

CONO list item 47, blood: 'C-Reactive Protein (CRP).' CONO list item 57, blood: 'Erythrocyte Sedimentation Rate (ESR) (Sedimentation Rate).' Distinct from item 48, 'C-Reactive Protein - High Sensitivity' (see High-sensitivity C-reactive protein (hs-CRP), a separate record restricted to cardiovascular risk stratification).

Linked conditions

• "Should I be tested?" for fibromyalgia ↗

Counselling script

“If there's a specific reason to look for inflammation, such as joint swelling or as part of a fibromyalgia work-up, I'll order CRP, and ESR alongside it where a guideline calls for both, so I'll do that today. CRP is the more reliable of the two for general use, so I don't use ESR as a stand-alone screening test in someone with no symptoms. If new symptoms suggesting inflammation come up later, we can check this then.”

Revisit if

• —Joint swelling, fever, or other features suggesting inflammatory or rheumatologic disease develop
• —Widespread pain being worked up for fibromyalgia
• —Symptoms persist or worsen despite a normal result

References

1. [1]Canadian Association of Medical Biochemists / Choosing Wisely Canada (2026). Choosing Wisely Canada: Medical Biochemistry, Ten Tests and Treatments to Question (Canadian Association of Medical Biochemists), recommendation #2: erythrocyte sedimentation rate (ESR). linkDon't order an ESR to screen asymptomatic patients or as a general test to look for inflammation in patients with undiagnosed conditions; only CRP should be used as a measure of systemic inflammation
2. [2]Canadian Pain Society / Canadian Rheumatology Association (Fitzcharles MA et al.) (2012). 2012 Canadian Guidelines for the diagnosis and management of fibromyalgia syndrome: executive summary. linkolder guidelineRecommendation 4: FM diagnosed as a clinical construct, with testing limited to CBC, ESR, CRP, creatine kinase and TSH; any additional testing should depend on the clinical evaluation (level 5, grade D)
3. [3]ACTTION-APS Pain Taxonomy (AAPT) / American Academy of Pain Medicine, American Pain Society (Arnold LM et al.) (2019). AAPT Diagnostic Criteria for Fibromyalgia. linkScreening laboratory tests sometimes obtained in fibromyalgia include ESR and/or CRP, CBC, a comprehensive metabolic panel, and thyroid function test
4. [4]Ontario Ministry of Health (2026). Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026) - L451 Sedimentation rate. linkSedimentation rate (L451) is listed by name in the 2026 OHIP Schedule of Benefits for Laboratory Services
5. [5]Ontario Ministry of Health (2026). Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026) - L665 C-Reactive protein. linkC-Reactive protein (L665) is listed by name in the 2026 OHIP Schedule of Benefits for Laboratory Services
6. [6]Government of Ontario (e-Laws) (2026). Health Insurance Act, R.R.O. 1990, Reg. 552: General, s. 22 (insured laboratory services). linkA lab test is insured only when ordered by a physician, midwife, or NP who has clinically assessed the patient
7. [7]Ontario Ministry of Health (2026). Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026). linkTests ordered by anyone other than an authorized provider, including NDs, are not insured services