The 2 Simple Tests That Can Spot Kidney Disease Before Symptoms Start
Kidney health probably isn't the first thing that comes to mind when you think about longevity. We talk a lot about maintaining muscle, protecting our heart, keeping blood sugar in check, and supporting brain health as we age. Our kidneys don’t always come up in conversation.
But these two small organs are doing a lot behind the scenes. They filter waste from the blood, balance fluids and electrolytes, help regulate blood pressure, and play a role in everything from red blood cell production to bone health.
What makes kidney health tricky is that changes in function can happen without you feeling any different. Chronic kidney disease can progress under the radar for years, with few or no obvious symptoms in its earlier stages.
A new landmark series1 published in The Lancet is drawing attention to just how common that problem has become, and why checking in on your kidneys may be an overlooked part of protecting your health for the long haul.
Kidney disease affects more than 800 million adults
The new series brought together researchers from around the world to look at the current state of chronic kidney disease (CKD), including how common it is, why we're missing so many cases, and what could help us catch it earlier.
CKD simply means the kidneys have been damaged or aren't filtering blood as well as they should over a sustained period of time. An estimated 788 to 844 million adults worldwide are living with it, and it's projected to become the fifth-leading cause of death globally by 2040.
Yet researchers estimate that 30 to 50% of CKD cases in high-income countries go undiagnosed. In some parts of the world, that number may be even higher.
A big part of the problem is that early kidney disease often doesn't come with obvious warning signs. Mild to moderate CKD can be completely asymptomatic, so someone may feel perfectly healthy while their kidney function is gradually declining.
Two simple tests can tell you a lot
This is where the research becomes especially actionable. You don't necessarily need advanced imaging or an expensive longevity panel to get a better idea of how your kidneys are doing.
There are two numbers worth knowing.
The first is your estimated glomerular filtration rate (eGFR). This is generally calculated from a blood test measuring creatinine and gives your doctor an estimate of how effectively your kidneys are filtering your blood. If you've had routine bloodwork recently, there's a decent chance you've already had this measured.
The second is a urine albumin-to-creatinine ratio (uACR). This checks for albumin, a protein that normally stays in the blood but can begin leaking into the urine when the kidneys are damaged.
And this second test is particularly worth asking about because you may not automatically get it with routine bloodwork. Someone can have a relatively normal eGFR and still have elevated albumin in their urine, so looking at both gives a more complete picture.
Some people have even more reason to get checked
Not everyone has the same risk of developing CKD. The researchers specifically point to diabetes, high blood pressure, obesity, cardiovascular disease, a family history of kidney disease, and older age as reasons to be more proactive about screening.
That's also where kidney health starts to look a lot like the rest of longevity medicine. The kidneys don't operate separately from your cardiovascular and metabolic health. High blood pressure can damage the tiny blood vessels in the kidneys over time, while persistently elevated blood sugar can damage their filtering system.
So protecting your kidneys doesn't require an entirely separate routine. Many of the basics you're hopefully already prioritizing matter here, too: stay active, don't smoke, keep blood pressure and blood sugar well managed, eat a nutrient-dense diet, and work with your doctor to manage cardiovascular or metabolic conditions early.
The takeaway
CKD is easy to miss, but fortunately, it can also be relatively simple to screen for. Knowing your eGFR and urine albumin levels can give you a much clearer picture of how your kidneys are functioning, often before symptoms ever show up.