High-sensitivity C-reactive protein (hs-CRP)

ND-recommended test reviewed: high-sensitivity C-reactive protein (hs-CRP).
Indications reviewed: cardiovascular risk stratification; standard risk calculation: ____ (not in the intermediate range).
Not ordered. Rationale discussed: hs-CRP adds only a small improvement to risk prediction and is not recommended for general population screening. Ref: USPSTF 2018 nontraditional risk factors statement.
Patient informed test available privately via ND. Patient given info page: https://labs.ajaxharwoodclinic.com/hs-crp/patient
Revisit if: cardiovascular risk calculation falls into the intermediate range and the statin decision is otherwise uncertain.

Indicated when

• —Adults at intermediate 10-year cardiovascular risk (7.5% to 19.9%) where the statin decision is otherwise uncertain; hs-CRP at or above 2.0 mg/L is treated as a risk-enhancing factor favouring statin therapy under the AHA/ACC risk framework [2]

Not indicated when

• —Routine or population-based screening of average-risk adults to detect cardiovascular risk; the USPSTF found current evidence insufficient to assess the balance of benefit and harm of adding hs-CRP to standard risk assessment for this purpose [1]
• —Investigating fatigue, general inflammation, or 'wellness' concerns without a specific cardiovascular risk-stratification question

Why not

For population-level cardiovascular screening, the USPSTF concluded the evidence is insufficient to know whether adding hs-CRP changes outcomes [1]. A large individual-participant meta-analysis found that adding CRP to conventional cardiovascular risk factors improved a standard measure of risk prediction (the C-index) by only 0.0039, a small increment [3]. hs-CRP is also non-specific: it rises with infection, injury, and many inflammatory conditions unrelated to cardiovascular risk, so a result outside the intended risk-stratification context is hard to interpret.

Better first step

Calculate standard cardiovascular risk first (age, sex, blood pressure, lipids, smoking, diabetes status); hs-CRP is only useful as an add-on when that calculation places the patient at intermediate risk and the result would change a shared decision about starting a statin [2].

Typical ND rationale

An ND may order hs-CRP reasoning that it is a sensitive marker of low-grade inflammation, which is linked to cardiovascular disease risk, and that catching it early could prompt earlier lifestyle or treatment changes.

Ontario coverage & CONO orderability

OHIP status

unverified

The 2026 Schedule of Benefits for Laboratory Services lists L665 'C-Reactive protein' (fee $3.72) by name, but the Schedule text found in this session does not distinguish a separate, high-sensitivity assay code from standard CRP. It is therefore not established whether L665 covers the specific high-sensitivity assay used for cardiovascular risk stratification, or only standard CRP testing for infection or inflammation. ND-ordered testing is patient-paid regardless of assay type (Reg. 552 s.22).

CONO orderable

Yes — CONO list #48

CONO list item 48, blood: 'C-Reactive Protein – High Sensitivity,' distinct from item 47 (standard CRP) and item 57 (ESR), which are related but not equivalent inflammatory markers.

Linked conditions

• dyslipidemia ↗

Counselling script

“hs-CRP isn't a general screening test, since it only slightly improves how well we predict cardiovascular risk for most people, so I'm not going to add it to your bloodwork today. It tends to matter when someone's standard risk calculation comes out in an uncertain middle range, where a high result can help decide whether to start a statin.”

Revisit if

• —Cardiovascular risk calculation newly falls into the intermediate range (7.5 to 19.9 percent 10-year ASCVD risk)
• —New family history of premature cardiovascular disease

References

1. [1]US Preventive Services Task Force (2018). Risk Assessment for Cardiovascular Disease With Nontraditional Risk Factors: US Preventive Services Task Force Recommendation Statement. linkInsufficient evidence to assess benefit or harm of adding hs-CRP, ABI, or CAC to standard cardiovascular risk assessment in asymptomatic adults
2. [2]American Heart Association / American College of Cardiology (multi-society) (2018). 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol. linkhs-CRP is listed among risk-enhancing factors supporting a statin-therapy discussion in adults at intermediate risk
3. [3]Emerging Risk Factors Collaboration (2012). C-reactive protein, fibrinogen, and cardiovascular disease prediction. linkolder guidelineAdding CRP to conventional risk factors produced only a small improvement in risk discrimination (C-index +0.0039)
4. [4]Ontario Ministry of Health (2026). Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026) - L665 C-Reactive protein. linkCRP (L665) 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). linkCommunity lab tests are insured only when ordered under the Schedule by an authorized prescriber
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