C-Reactive Protein · high result
High CRP: what it means, what the level points to and when it is urgent
Short answer
A high C-reactive protein means the body is mounting an inflammatory response right now. CRP rises within 6–12 hours of infection, injury, surgery or an inflammatory flare and falls within days once the cause resolves. The size of the rise is the clue: 10–40 mg/L fits viral illness, mild inflammation, obesity or late pregnancy; 40–200 fits bacterial infection or an active inflammatory disease; above 200 fits severe bacterial infection, sepsis, major trauma or burns. CRP never names the cause — the history, examination and other tests do.
Medically reviewed by Youmna DiStefano, MD · Last reviewed November 2026
When does this result need same-day care?
- A very high CRP (above about 100 mg/L) with fever, rigors, confusion, a fast heart rate or low blood pressure — possible sepsis; emergency care
- New severe headache with scalp tenderness, jaw pain or visual loss and a raised CRP in someone over 50 — same-day assessment for giant cell arteritis (vision is at stake)
- A hot, swollen joint with fever — possible septic arthritis; same-day care
What is the normal range for C-Reactive Protein?
- age 18+: 0 – 10 mg/L
Often reflects infection, injury, or active inflammatory disease.
Full reference table, citations and testing options: C-Reactive Protein biomarker page.
What are the common causes of high C-Reactive Protein?
- Bacterial infections — pneumonia, urinary and kidney infection, cellulitis, abscess, endocarditis, sepsis; typically 40–200+ mg/L
- Viral infections — usually under 40 mg/L; influenza and COVID can go higher
- Active inflammatory disease — rheumatoid arthritis, polymyalgia rheumatica and giant cell arteritis, inflammatory bowel disease, vasculitis, gout flares (lupus often spares CRP)
- Tissue injury — surgery (peaks at 48–72 hours), trauma, burns, heart attack, pancreatitis, deep-vein thrombosis
- Cancer — lymphoma, kidney, lung and other solid tumors, especially with weight loss or night sweats
- Chronic low-grade causes of a mildly raised CRP (3–10 mg/L): obesity, smoking, periodontal disease, obstructive sleep apnea, poorly controlled diabetes, chronic kidney disease
- Late pregnancy, oral contraceptives and hormone therapy (modest rises), and intense exercise in the previous day
- Rare — familial Mediterranean fever and other autoinflammatory syndromes, with recurrent fevers
What symptoms go with high C-Reactive Protein?
- Those of the cause — fever, chills, cough, urinary symptoms, a red hot joint, abdominal pain, a swollen limb
- Morning stiffness lasting more than an hour, joint swelling, shoulder and hip girdle pain (inflammatory arthritis, polymyalgia)
- New headache, scalp tenderness, jaw pain on chewing or visual change in someone over 50 (giant cell arteritis — urgent)
- Unexplained weight loss, night sweats or fatigue with a persistently raised CRP
What do clinicians usually check next?
- Match the number to the picture: a high CRP with an obvious infection or recent surgery needs no work-up of its own, just a repeat after recovery
- A complete blood count with differential, and an ESR — CRP rises and falls faster than ESR, so the pair dates the inflammation
- Cultures and imaging as the symptoms direct when infection is suspected; urinalysis for a urinary source
- Rheumatoid factor, anti-CCP, ANA and a joint examination when joints are involved; fecal calprotectin for gut symptoms
- Repeat in 2–4 weeks: a CRP that returns to normal closes the question; one that stays above about 10 mg/L without an explanation is pursued with a careful history, examination and age-appropriate cancer screening
- For cardiovascular risk, order the high-sensitivity CRP instead — standard CRP cannot resolve the 1–3 mg/L range that matters there
Follow-up tests available at TestWell: Body Inflammation Test (ESR) ($18.99), Autoimmune Antibody Screen (ANA) ($32.99), Rheumatoid Factor Test (RF) ($19.99), Rheumatoid Arthritis Antibody Test (Anti-CCP) ($32.99), Fecal Calprotectin Test (Stool) ($139.99), Sed Rate Test (ESR) ($24.99).
How do you recheck C-Reactive Protein?
Prices are cash-pay; every order adds one $6 lab processing fee. Physician authorization is included; no insurance or referral needed.
| Test or panel | Type | Price | Fasting | Results |
|---|---|---|---|---|
| C-Reactive Protein Test (CRP) | Test | $26.99 | No | 2–4 business days |
Common questions
What does a high CRP mean?
That there is active inflammation somewhere — infection, injury, surgery, an inflammatory disease flare or, less often, cancer. CRP rises within hours and falls within days of the cause resolving, so it dates and sizes the inflammation but does not name it. The level helps: under 40 mg/L fits viral illness or mild inflammation, 40–200 bacterial infection or active inflammatory disease, above 200 severe infection or major tissue injury.
What level of CRP is dangerous?
There is no single dangerous number — a CRP of 150 after hip surgery is expected, while 30 in a well person is unexplained. Values above about 100 mg/L usually mean bacterial infection or major tissue injury, and with fever, confusion or low blood pressure they are a sepsis warning. A persistently raised CRP above 10 with no explanation is investigated rather than watched.
How long does CRP stay high?
It peaks about 48 hours after the trigger and has a half-life of about 19 hours, so it falls by roughly half every day once the cause is treated — back to normal within one to two weeks after an uncomplicated infection or operation. A CRP that stays up means the process is ongoing.
What is the difference between CRP and hs-CRP?
The same protein measured on two scales. Standard CRP reports in whole mg/L from about 3–10 upward and is used for infection and inflammatory disease. High-sensitivity CRP resolves 0.1–10 mg/L and is used to grade long-term cardiovascular risk (below 1 low, 1–3 average, above 3 high). A standard CRP cannot answer the cardiovascular question, and an hs-CRP above 10 is read as acute inflammation and repeated.
Educational content, not a diagnosis. Lab results are one input; a clinician interprets them with your history and exam.