What is a normal hs-CRP level?

The categories come from the 2003 CDC/AHA statement. They were set as approximate thirds of the adult population, pooled from more than 15 populations and 40,000 people [1].

The 2018 AHA/ACC cholesterol guideline adds a single cut point: 2.0 mg/L (0.2 mg/dL) or more counts as a risk-enhancing factor [4].

People often search for an hs-CRP score because some reports print a risk label next to the value. That label is the CDC/AHA category, not a calculated score [1]; the result itself is simply the concentration.

Two cautions when reading the number:

• Check the unit. 2 mg/dL is 20 mg/L, a very different result from 2 mg/L. Multiply mg/dL by 10 to get mg/L.
• Check how you felt. A value taken during or soon after an illness does not belong in the heart-risk categories [1].

Healthy young adult blood donors had a median of 0.8 mg/L [5]. In another donor group, the median was 0.64 mg/L, with the middle 95% between 0.08 and 3.11 mg/L [2].

General adult populations run higher because they include people with more body fat, smoking and chronic disease. The CDC/AHA cut points at 1 and 3 mg/L were chosen as approximate population thirds, and in most populations more than 95% of people are under 10 mg/L [1]. In the Dallas Heart Study, 31% of white men and 58% of Black women were over 3 mg/L [3].

In 2,749 adults aged 30 to 65, women had higher CRP than men (median 3.3 versus 1.8 mg/L) and Black participants higher than white participants (3.0 versus 2.3 mg/L). After adjusting for risk factors, estrogen use, statins and BMI, women were still more likely to be over 3 mg/L [3]. Estrogen and progestogen therapy itself raises hs-CRP [1].

The same uniform cut points still apply to everyone. The study's authors called for research on whether thresholds should be adjusted by sex or race [3].

For age, a study of healthy donors found only a weak association [2]. CRP tends to be higher in older groups mainly because body fat, smoking history and chronic disease accumulate [6] [7].

Risk rises steadily with CRP, without a clear threshold: each threefold higher CRP carried about 37% more coronary risk after adjustment [8]. That makes "optimal" a matter of where on a slope you sit, rather than a cut point.

In heart patients, trials found the best outcomes when hs-CRP fell below 2 mg/L together with LDL cholesterol below 70 mg/dL [9]. For people without heart disease, under 1 mg/L is the lowest category [1].

A very low result is not a problem in itself. No source we reviewed links low hs-CRP to harm.

In 27,939 women, CRP and LDL cholesterol were almost uncorrelated (r = 0.08), and each predicted events independently [10]. Over 30 years, hs-CRP, LDL cholesterol and lipoprotein(a) each added separate information, and risk was clearest with all three [11].

That is why the CDC/AHA statement framed hs-CRP as an adjunct to the major risk factors, not an alternative to them [1]. A normal result is reassuring about inflammation; it says nothing about ApoB, LDL cholesterol, lipoprotein(a), blood pressure or glucose.