Calcium Score Test: What Your Coronary Calcium Score Means
A coronary artery calcium scan measures calcified plaque in the heart's arteries. Learn what a score of 0, 1 to 99, 100 to 399, or 400 and above means, and how it fits with ApoB and Lp(a).
- Published
- October 5, 2026
- Read time
- 12 min read
- Medically reviewed by
-
Rhonda Collins, FNP-C
A calcium score test, also called a coronary artery calcium (CAC) scan or heart scan, is a short, non-contrast CT scan that measures calcified plaque in the arteries that supply your heart. The result is a number, the Agatston score. A score of 0 means no calcified plaque was found. Any score above 0 means plaque is present, and higher scores mean more of it. Current US cholesterol guidelines use the score to decide whether some adults at borderline or intermediate risk should start cholesterol-lowering treatment.
What is a coronary artery calcium scan?
A coronary artery calcium scan is a cardiac CT scan that looks for calcium deposits in the walls of the coronary arteries. Those deposits are part of atherosclerotic plaque, so the amount of calcium works as a measure of how much hardened plaque has built up. The scan uses no dye and no IV, and the exam takes less than 20 minutes. RadiologyInfo describes the procedure [1].
The scan has two important limits. It only sees plaque that has calcified. Softer, non-calcified plaque does not show up, and the scan does not show whether an artery is narrowed. RadiologyInfo states both limits [1].
What does your calcium score mean?
Your coronary calcium score reflects the total calcified plaque across your coronary arteries. The categories below are the ones most reports and reviews use. A 2023 review of CAC scoring in asymptomatic adults summarizes these bands [2].
| Calcium score (Agatston) | What it indicates |
|---|---|
| 0 | No calcified plaque detected; low near-term risk |
| 1 to 99 | Mild calcified plaque |
| 100 to 399 | Moderate calcified plaque |
| 400 and above | Extensive calcified plaque; high risk of future events |
The Society of Cardiovascular Computed Tomography’s CAC-DRS reporting system draws the upper bands slightly differently, at 100 to 299 and 300 and above, so your report may use either set. The SCCT CAC-DRS consensus document sets out this system [3].
Higher scores track with higher risk. In the Multi-Ethnic Study of Atherosclerosis (MESA), about 6,700 adults without known heart disease were followed for a median of 3.8 years. Compared with people who had no coronary calcium, those with scores of 101 to 300 had about 7.7 times the adjusted risk of a coronary event, and those above 300 had about 9.7 times the risk. The score predicted risk in all four racial and ethnic groups studied. Detrano and colleagues reported these results in the New England Journal of Medicine [4].
What is a normal calcium score for your age?
Calcium builds with age and is higher in men, so reports also give a percentile that compares your score with people of the same age and sex. The 2026 US dyslipidemia guideline treats a score at or above the 75th percentile like a score of 100 or more when it recommends cholesterol-lowering therapy. The University of Illinois drug information group summarizes the guideline’s CAC recommendations [5]. For median scores and percentiles at each age from 40 to 80, see the calcium score by age chart.
What does a calcium score of 0 tell you?
A calcium score of 0 means no calcified plaque was detected. It is one of the strongest signs of low near-term cardiovascular risk. A 2023 review describes a score of 0 as the strongest negative risk factor for cardiovascular disease. The 2023 CAC review makes this point [2].
A zero score does not mean zero risk. It cannot rule out soft plaque that has not calcified yet. RadiologyInfo notes this limitation [1]. It also has a shelf life. In MESA participants who started at 0, about half had measurable calcium 10 years later, and people with diabetes developed it sooner. Dzaye and colleagues modeled this “warranty period” [6]. Smoking also matters. In a MESA analysis of smokers, 6.7% of those with a zero score still had a cardiovascular event over about 11 years of follow-up. That figure comes from the MESA smokers analysis [7].
Who should get a calcium score test?
A calcium score test is most useful when the result would change a decision, usually whether to start cholesterol-lowering medicine. The 2026 ACC/AHA Guideline on the Management of Dyslipidemia, which replaced the 2018 cholesterol guideline, recommends selective CAC scanning for men 40 and older and women 45 and older whose 10-year risk of heart attack or stroke is borderline (3% to under 5%) or intermediate (5% to under 10%) on the AHA PREVENT calculator. The recommendation appears in the guideline record [8] and the American College of Cardiology’s summary [9].
For those adults, the guideline ties the score to treatment:
- Score of 0: if you prefer to avoid lipid-lowering therapy and have no higher-risk conditions, it is reasonable to defer treatment and repeat the scan in 3 to 7 years.
- Score above 0: starting lipid-lowering therapy is recommended, particularly when the score is 100 or more or at or above the 75th percentile for your age and sex.
- Any calcium: supports an LDL cholesterol goal under 100 mg/dL, with lower goals as the score rises.
These points come from the University of Illinois guideline summary [5] and the ACC summary [9].
Who should not use a calcium score as a screening test?
- Anyone with symptoms. Chest pain, pressure, or unexplained shortness of breath needs urgent medical care, not a screening scan.
- People with known heart disease, such as a prior heart attack, stent, or bypass. The score would not change the fact that treatment is already indicated.
- People at low estimated risk, where the guideline does not recommend routine scanning.
- People who are pregnant. CT is generally not recommended during pregnancy unless medically necessary. RadiologyInfo explains why [1].
How much radiation does a calcium score scan use?
A cardiac CT for calcium scoring delivers an effective dose of about 1.7 mSv, roughly the natural background radiation you would receive over 6 months. RadiologyInfo lists this dose [10]. The exact dose depends on the scanner and protocol. A 2023 review reports about 1.0 to 1.9 mSv for multidetector CT, depending on sex. That range comes from the 2023 CAC review [2].
The scan also captures part of the lungs and upper abdomen, so it can find things unrelated to the heart. Small lung nodules are the most common incidental finding, especially in older adults and people who smoke. Some of these findings lead to follow-up imaging. Bos and Leening describe the range of incidental findings on calcium scans [11].
How does a calcium score fit with ApoB and Lp(a)?
A calcium score and blood lipid markers answer different questions. The calcium score shows how much calcified plaque has already built up. Apolipoprotein B (ApoB) counts the cholesterol-carrying particles that drive plaque now. Lipoprotein(a), or Lp(a) is a largely inherited particle that adds risk on top of LDL cholesterol. Read together, they show both the damage so far and the forces still acting on your arteries.
The 2026 dyslipidemia guideline recommends measuring Lp(a) at least once in adulthood. It treats levels around 50 mg/dL (about 125 nmol/L) as meaningful risk, and ApoB measurement as reasonable for guiding how intensively to treat. The ACC’s top 10 points cover the Lp(a) thresholds [12], and its guideline summary covers ApoB [9].
Research that combines the two supports reading them side by side. In a 2022 study of MESA and Dallas Heart Study participants, a high Lp(a) and a positive calcium score each raised risk independently. People with both a high Lp(a) and a score of 100 or more had about 4.7 times the risk of those with neither. People with a high Lp(a) but a score of 0 had risk that was not clearly different from the reference group over about 13 years. Mehta and colleagues published these findings in JACC [13].
How the combinations generally read:
| Calcium score | ApoB or Lp(a) | What the combination suggests |
|---|---|---|
| 0 | Normal | Lowest near-term risk in this set; the guideline’s rescan window is 3 to 7 years |
| 0 | High | No calcified plaque yet, but the blood markers show ongoing risk; a zero score does not cancel a high Lp(a) or ApoB |
| Above 0 | Normal | Plaque is present even though lipid markers look fine; the guideline recommends lipid-lowering therapy at this point |
| Above 0 | High | Plaque is present and the drivers are still elevated; in the MESA data, high Lp(a) with a score of 100 or more was highest |
To compare what these blood tests cost, see the ApoB test cost guide, the Lp(a) test cost guide, and the lipid panel cost guide. For more on why ApoB matters, read Mito’s ApoB heart-health guide.
Can you lower your calcium score?
Treatment after a positive scan aims to lower your risk of a heart attack or stroke, not the number itself, and the score can even rise on treatment. In a pooled analysis of 8 trials that tracked coronary plaque with intravascular ultrasound, high-intensity statins shrank overall plaque volume while plaque calcium still increased. The researchers concluded that statins promote plaque calcification, which may help stabilize plaque. Puri and colleagues reported this analysis in JACC [14].
So a higher score on a statin does not by itself mean treatment is failing. Progress is better judged by the markers treatment acts on, such as LDL cholesterol and ApoB, along with blood pressure, blood sugar, and smoking status.
How often should you repeat a calcium score test?
For a score of 0, the 2026 guideline suggests a repeat scan in 3 to 7 years for adults who deferred treatment. This interval comes from the University of Illinois guideline summary [5]. The MESA warranty-period analysis supports a similar 3 to 7 year window. The interval runs shorter for people with diabetes. Both points come from the Dzaye analysis [6].
For a score above 0, repeat scanning is less useful, because statins can raise the score even while plaque stabilizes. If your score is positive, talk with your doctor about whether a repeat scan would change your treatment before booking one.
How to prepare for a calcium score scan
Preparation is simple, but instructions vary by imaging center. For calcium score scans booked through Mito, the partner facility’s published pre-test instructions are:
- No alcohol or caffeine for 4 hours before the scan.
- No strenuous exercise for at least 24 hours before the scan.
- Wear clothes you can easily remove. You will change into a gown.
- No metal or hard plastic, such as zippers, buttons, jewelry, watches, hair clips, or underwire bras.
These come from the provider’s published test protocols [15]. Other centers may ask you to avoid food, caffeine, and smoking for 4 hours. RadiologyInfo lists typical instructions [1].
During the scan, you lie on a table that moves through the CT scanner. There is no injection, the scan is painless, and you can return to normal activities right away. RadiologyInfo describes the exam [1].
Getting a calcium score scan through Mito
Mito offers a Coronary Artery Calcium (CAC) Scan at a partner facility near you. Before you order, a short eligibility check confirms that you:
- are 40 to 75 years old;
- have at least one listed risk factor: a family history of cardiovascular disease, high cholesterol or high blood pressure, diabetes, a BMI above 25, a sedentary lifestyle, or smoking;
- have no symptoms of heart disease and no diagnosed heart disease; and
- are not pregnant.
When you book, you also add your primary care doctor’s name and phone number. For what a scan costs with and without insurance, see the calcium score test cost guide, and to compare Mito with other providers, see the CAC scan price comparison. If you are under 40, ApoB and Lp(a) blood tests are a way to learn about your cardiovascular risk before a scan is appropriate.
Frequently asked questions
Do you have to fast before a calcium score test?
Usually not, but instructions vary by center. Mito’s partner facility asks you to skip alcohol and caffeine for 4 hours and strenuous exercise for 24 hours, while some other centers ask you to avoid food as well.
How long does a calcium score test take?
The exam takes less than 20 minutes, and you can go back to normal activities right away.
Is a high calcium score a death sentence?
No. A high score means more plaque and a higher risk of future events, which is exactly why it guides treatment. Current guidelines use it to decide how intensively to lower LDL cholesterol.
What is a good calcium score?
A score of 0 is the best result, meaning no calcified plaque was detected. For a score above 0, the percentile for your age, sex, and race or ethnicity tells you how it compares with your peers.
Does a calcium score test use contrast dye?
No. A calcium score scan is a non-contrast CT, so there is no IV or dye.
Is a calcium score the same as a coronary CT angiogram?
No. A calcium score scan measures calcified plaque without dye. A coronary CT angiogram (CCTA) uses an IV contrast injection to show whether plaque has narrowed the arteries, and it is commonly used to evaluate chest pain. RadiologyInfo describes coronary CTA [16].
Photo by Holly Mandarich on Unsplash.
References
- RadiologyInfo: Cardiac CT for Calcium Scoring
- Review of coronary artery calcium scoring in asymptomatic adults (2023), PMC10635695
- SCCT CAC-DRS consensus document (PubMed 29793848)
- Detrano and colleagues, New England Journal of Medicine: MESA coronary calcium and coronary events (PubMed 18367736)
- University of Illinois Drug Information Group: Key updates from the 2026 ACC/AHA dyslipidemia guideline
- Dzaye and colleagues: MESA calcium score “warranty period” analysis (PubMed 33129734)
- MESA analysis of coronary calcium and cardiovascular events in smokers (PubMed 29454784)
- 2026 ACC/AHA Guideline on the Management of Dyslipidemia (PubMed 41824590)
- American College of Cardiology: ACC/AHA release new clinical guideline for managing dyslipidemia
- RadiologyInfo: Radiation Dose in X-Ray and CT Exams
- Bos and Leening: Incidental findings on coronary calcium scans, PMC5986828
- American College of Cardiology: Top 10 points from the 2026 dyslipidemia guideline (ACCEL Lite, April 2026)
- Mehta and colleagues, JACC: Lipoprotein(a) and coronary artery calcium in MESA and the Dallas Heart Study (PubMed 35210030)
- Puri and colleagues, JACC: Statins and coronary plaque calcification, pooled intravascular ultrasound analysis (PubMed 25835438)
- Fitnescity: Test protocols
- RadiologyInfo: Coronary CT Angiography
Tests discussed in this guide
Apolipoprotein B (Apo B) Blood Test
Estimate the number of atherogenic lipoprotein particles that can enter the artery wall, not just the cholesterol they carry.
Lipoprotein(a) (Lp(a)) Blood Test
Reveal an inherited cardiovascular risk factor that a standard lipid panel can miss.
The standard cholesterol workup for cardiovascular risk, and the baseline for tracking diet, exercise, or statin response.
