What are the early warning signs of kidney disease and how do doctors test for it?
Because the kidneys are highly adaptable, they can keep doing their job even when they are partially damaged. This means Chronic Kidney Disease (CKD) usually has zero noticeable symptoms in its earliest stages.
By the time physical symptoms appear, the kidneys are often working significantly below their full capacity.
Early to Moderate Warning Signs
As kidney function declines, waste products and fluid start building up in the body. Look out for these common red flags:
Swelling in Ankles, Feet, or Hands: Damaged kidneys struggle to remove extra fluid, leading to sodium retention and fluid buildup (called edema). You might also notice puffiness around your eyes, especially in the morning.
Changes in Urination: You may need to urinate much more frequently—especially at night (called nocturia). The urine might also appear foamy or bubbly, which indicates that protein is leaking into it.
Severe Fatigue and "Brain Fog": A severe drop in kidney function leads to a buildup of toxins in the blood. This can make you feel unusually tired, weak, or unable to concentrate.
Shortness of Breath: Fluid can build up in the lungs, or anemia (a low red blood cell count, common in kidney disease) can leave you feeling winded.
Dry, Itchy Skin: When the kidneys can no longer keep the right balance of minerals and nutrients in your blood, it can cause severe bone and mineral disease, often showing up as incredibly itchy, dry skin.
How Doctors Test for Kidney Disease
You cannot rely on physical symptoms alone to find kidney issues early. Doctors use two quick, routine tests to check how well your kidneys are functioning. They are typically ordered together as part of a Kidney Function Test (KFT) or metabolic panel.
1. The Blood Test: eGFR (Estimated Glomerular Filtration Rate)
This test checks how well your kidneys filter waste. The lab measures the amount of creatinine (a normal waste product from muscle breakdown) in your blood and plugs it into a formula along with your age and sex to calculate your eGFR.
What the numbers mean: An eGFR score of 90 or above is generally considered normal. A score below 60 sustained for three months or more indicates chronic kidney disease.
2. The Urine Test: uACR (Urine Albumin-to-Creatinine Ratio)
Healthy kidneys filter out waste but keep large things like proteins inside the body. If the kidney filters are damaged, a protein called albumin slips through into the urine.
What the numbers mean: A uACR score below 30 mg/g is normal. Anything higher means protein is leaking, which is often the very first indicator of kidney stress—long before the eGFR blood score begins to drop.
Who should get tested regularly? If you have diabetes or high blood pressure, you are at the highest risk. Doctors recommend getting both the blood eGFR and urine uACR tests done at least once a year to catch any changes early.
