Chronic kidney disease is a strong predictor of heart attack, stroke and heart failure, and one that is easy to overlook. As kidney function falls, cardiovascular risk climbs in step. For most people with reduced kidney function, the heart is the larger threat: they are far more likely to die than to ever need dialysis.
The link is now built into how heart risk is calculated. Kidney function is one of the inputs to the PREVENT equations used in US guidelines, and doctors increasingly manage the heart, the kidneys and metabolism as one connected system.
Key takeaways
- Cardiovascular risk rises in a graded way once kidney filtration drops below a certain level.
- Two tests describe kidney health: eGFR from a blood sample and albumin from a urine sample.
- Urine albumin often adds more to heart risk prediction than eGFR does.
- The PREVENT calculator counts kidney function among its core inputs.
- Heart and kidney disease share causes, so they are checked and managed together.
Two numbers describe kidney health
The first is the estimated glomerular filtration rate, or eGFR. It is calculated from creatinine in a blood sample and estimates how much blood the kidneys filter each minute. A lower number means less filtering capacity.
The second is urine albumin, usually reported as the albumin-to-creatinine ratio. Healthy kidneys keep albumin, a blood protein, out of the urine. Finding it there is a sign that the filters are leaking, and it can appear while eGFR is still normal.
The two tests measure different things, and both carry information about the heart.
How much kidney function matters
A study of 1,120,295 adults in a large California health system tracked eGFR against later outcomes. After adjustment for other factors, the risk of cardiovascular events rose steadily as eGFR fell below 60.1
| eGFR | Risk of cardiovascular events compared with an eGFR of 60 or higher |
|---|---|
| 45 to 59 | 1.4 times as high |
| 30 to 44 | 2.0 times as high |
| 15 to 29 | 2.8 times as high |
| Below 15 | 3.4 times as high |
The risk of death and of hospitalization followed the same graded pattern. The researchers described the association as independent of other known risk factors.
A second study shows where the danger lies. It followed almost 28,000 people with reduced kidney function for five years. Among those in stage 3, 1.3% went on to dialysis or a transplant, while 24.3% died. The authors concluded that death was far more common than dialysis at every stage they examined.2
Albumin in the urine: an early signal
The Chronic Kidney Disease Prognosis Consortium pooled data on 637,315 people without known cardiovascular disease from 24 cohorts. Adding eGFR and urine albumin to the traditional risk factors improved the prediction of cardiovascular outcomes, and the improvement was greater with albumin than with eGFR.3
The gain was most evident for cardiovascular death and heart failure, and in people with diabetes or high blood pressure. For people who already had chronic kidney disease, the two kidney measures together outperformed most single traditional risk factors.3
In plain terms, a simple urine test says something about your heart that a cholesterol panel does not.
Kidney function in the PREVENT calculator
The American Heart Association's PREVENT equations were developed with kidney researchers for this reason. They add eGFR to the traditional inputs of age, blood pressure, cholesterol, diabetes and smoking, and the urine albumin-to-creatinine ratio can be entered as an optional extra.4
PREVENT also predicts heart failure alongside heart attack and stroke. That matters here, because heart failure is one of the outcomes most closely tied to kidney disease.
Our guide to the PREVENT risk calculator explains the inputs and the risk bands. If your eGFR has never been entered into a risk estimate, your number may not reflect your kidneys at all.
Why the two are managed together
The heart and kidneys share causes. High blood pressure and diabetes damage both, and each organ's decline makes the other's worse. Our guide to diabetes and heart disease risk covers the diabetes side.
In 2023 the American Heart Association formalized this view in a presidential advisory on cardiovascular-kidney-metabolic health. It describes the interplay among metabolic risk factors, chronic kidney disease and the cardiovascular system, and it calls for care that is less fragmented between specialties.5
The advisory also notes a growing number of treatments that improve metabolic risk factors, kidney function or both and that protect the heart as well. Which of these applies to you is a decision for your own clinicians.
US cholesterol guidance has reflected the link for some time. The 2018 cholesterol guideline listed chronic kidney disease among the risk-enhancing factors that favor treatment when calculated risk is intermediate.6
What gets checked
- eGFR. Creatinine is part of many routine blood panels, so you may already have a result.
- Urine albumin-to-creatinine ratio. This is ordered less often and is worth asking about, especially if you have diabetes or high blood pressure.
- Blood pressure. It is both a cause and a consequence of kidney damage.
- Blood sugar and A1c. Diabetes is a common cause of kidney disease.
- A lipid panel. Kidney disease does not replace the usual cholesterol assessment.
A single abnormal kidney result is usually repeated before any conclusion is drawn, because kidney results can vary from one test to the next.
Your next step
Look at your most recent bloodwork for an eGFR value, and ask your clinician whether a urine albumin test has been done. Our guide to a heart disease risk assessment explains how results like these are combined.
You can also answer the three quick questions in the screener on the Cardio Res-Q program page. Kidney disease is among the risk factors listed on that page. If you want to know which kidney tests are part of an assessment, ask our team.
Are You a Candidate for Cardio Res-Q?
Three quick questions about the risk factors we screen for. Your answers stay between you and the clinic.
Frequently asked questions
At what eGFR does heart risk start to rise?
In the large California study, cardiovascular risk was measurably higher once eGFR fell below 60 and kept rising at lower levels. A single reading is not a diagnosis. Your clinician will look at the trend and at urine albumin before drawing conclusions.
My eGFR is normal. Do I still need a urine test?
It can be worth asking, particularly if you have diabetes or high blood pressure. Albumin can show up in the urine before eGFR drops, and in pooled studies it added more to heart risk prediction than eGFR did. Whether you need the test is a question for your clinician.
Does kidney disease cause heart disease, or the other way around?
Both directions are recognized. Reduced kidney function is linked to higher cardiovascular risk independent of other factors, and a struggling heart can in turn affect the kidneys. The two also share causes, chiefly high blood pressure and diabetes.
If I have kidney disease, should I see a cardiologist?
Not automatically. Many people have their heart risk managed by a primary care doctor or kidney specialist. What matters is that someone is tracking blood pressure, cholesterol and blood sugar with your kidney results in view. Ask your clinician who that is.
Related reading
This article is for general education and is not medical advice. Decisions about testing and medication should be made with your clinician. If you have chest pain or other symptoms of a heart attack, call 911.
