The only reliable way to know if your kidneys are healthy is through two simple blood and urine tests your doctor can order. Kidneys can lose up to 50% of their function before you notice any symptoms, which is why the disease is often called “silent.” But there are physical signs worth watching for, risk factors that raise your odds, and habits that protect kidney function over time.
The Two Tests That Actually Tell You
Kidney health comes down to two measurable things: how well your kidneys filter blood and whether they’re leaking protein into your urine. Both can be checked with routine lab work.
The first is your estimated glomerular filtration rate, or eGFR. This number comes from a standard blood test that measures creatinine, a waste product your muscles produce. A healthy eGFR is 60 or higher. Below 60 suggests kidney disease, and 15 or lower points to kidney failure. Your result will appear on basic metabolic panels, so you may already have this number from a recent physical.
The second is your urine albumin-to-creatinine ratio, or uACR. This checks whether your kidneys are letting a protein called albumin slip through their filters. A normal result is less than 30 mg/g. Between 30 and 299 mg/g means your kidneys are leaking small amounts of protein, which raises your risk of kidney failure, heart failure, and stroke. At 300 mg/g or higher, confirmed on a repeat test, kidney disease is likely already present.
If you’re over 60, have diabetes or high blood pressure, or have a family history of kidney problems, getting both tests annually is a straightforward way to catch trouble early. For everyone else, these numbers will show up during routine checkups if your doctor orders standard bloodwork.
Physical Signs Your Kidneys May Be Struggling
Most kidney problems produce no symptoms until they’ve progressed significantly. But there are a handful of changes worth paying attention to.
Foamy urine is one of the more noticeable early clues. When albumin leaks into urine, it acts like soap, reducing the surface tension of the liquid and creating persistent bubbles that don’t disappear after one flush. In one study of patients who visited a clinic specifically because of foamy urine, about 22% had significant protein loss. When researchers included smaller amounts of protein leakage, the proportion was even higher. Occasional foam from a strong urine stream is normal, but foam that consistently lingers is worth mentioning to your doctor.
Other signs the National Kidney Foundation highlights include needing to urinate more often at night, puffiness around the eyes (from protein loss), swollen feet and ankles (from salt retention), persistently dry and itchy skin, and pink or cola-colored urine. The color change happens when damaged kidney filters let blood cells leak into urine. None of these symptoms are unique to kidney disease, but when several show up together, they paint a clearer picture.
Risk Factors That Matter Most
Diabetes and high blood pressure are responsible for the majority of kidney disease cases, and they damage the kidneys through a specific, well-understood process.
Your kidneys contain roughly a million tiny filtering units, each built around a cluster of blood vessels called a glomerulus. High blood pressure forces too much pressure into these delicate vessels, physically stretching the cells that make up the filter walls. Under repeated cycles of stretch and relaxation, the cells change shape, produce scar tissue, and gradually lose their ability to filter properly. Even blood pressure that sits in the 130/80 to 140/90 range, which many people consider “borderline,” leads to measurable kidney decline. Research tracking diabetic patients in that blood pressure range found that 30% developed protein leakage over the following 12 to 15 years.
High blood sugar makes the damage worse. Excess glucose accelerates scar tissue production in those same stretched cells and generates harmful compounds that trigger further inflammation. Diabetes also impairs the kidneys’ ability to regulate blood flow through their own filters, meaning even normal systemic blood pressure can translate into elevated pressure inside the kidney itself. This is why people with diabetes can develop kidney damage even when their blood pressure readings look acceptable.
Beyond diabetes and high blood pressure, other notable risk factors include a family history of kidney disease, being over 60, obesity, smoking, and frequent use of certain medications.
Over-the-Counter Painkillers and Kidney Risk
Nonsteroidal anti-inflammatory drugs like ibuprofen and naproxen are some of the most commonly used medications in the world, and they carry a real, dose-dependent risk to your kidneys. These drugs work by blocking compounds called prostaglandins, which also happen to keep the blood vessels feeding your kidneys dilated. When those vessels constrict, blood flow to the kidneys drops, and with it, their ability to function.
Occasional use at recommended doses (up to 1,200 mg per day for ibuprofen, 660 mg per day for naproxen) is generally safe for people with healthy kidneys. The risk climbs with higher doses, longer durations, and dehydration. Complications from overuse range from elevated blood pressure and fluid retention to acute kidney injury and, in severe cases, permanent damage to kidney tissue. If you rely on these painkillers regularly for chronic pain, that’s a conversation worth having with your doctor, especially if you have any other risk factors.
Daily Habits That Protect Kidney Function
Sodium intake is one of the most actionable things you can control. Major health organizations recommend keeping sodium below 2,300 mg per day for healthy adults. The World Health Organization sets its target even lower, at 2,000 mg. For people who are middle-aged, older, Black, or already managing high blood pressure, a limit of 1,500 mg per day offers more protection. Most Americans consume well over 3,400 mg daily, primarily from processed and restaurant foods rather than the salt shaker.
Staying well hydrated helps your kidneys clear waste efficiently. Water is ideal. There’s no magic number for daily intake, but pale yellow urine generally signals adequate hydration. Dark, concentrated urine means your kidneys are working harder than they need to.
Blood pressure and blood sugar management are the two highest-impact interventions if you carry those risk factors. Keeping blood pressure below 130/80 and maintaining stable blood sugar levels dramatically slows the cellular damage inside kidney filters described earlier. Regular exercise, maintaining a healthy weight, and limiting alcohol all contribute to both of those goals simultaneously.
How Often to Check
If you have no risk factors and feel fine, kidney function will typically be screened during routine bloodwork at your annual physical. If you have diabetes, high blood pressure, heart disease, or a family history of kidney problems, annual eGFR and uACR testing gives you the earliest possible window to catch changes. Early-stage kidney disease is highly manageable. The damage that accumulates silently over a decade is much harder to reverse. Getting those two numbers is the simplest, most reliable answer to whether your kidneys are healthy.