A low eGFR means your kidneys aren’t filtering blood as efficiently as expected. eGFR stands for estimated glomerular filtration rate, and it’s measured in milliliters per minute. A normal result is 90 or above, so anything consistently below 60 is considered a sign of reduced kidney function and may indicate chronic kidney disease (CKD).
What eGFR Actually Measures
Your kidneys contain tiny filtering units that clean waste products from your blood. The eGFR estimates how much blood those filters process each minute. Labs calculate it using your creatinine level (a waste product from normal muscle activity), your age, and your sex. The higher the number, the better your kidneys are working.
Until recently, eGFR equations included a race-based adjustment that could mask kidney disease in Black patients. In 2021, the National Kidney Foundation and the American Society of Nephrology recommended dropping the race variable entirely and switching to an updated formula called the CKD-EPI 2021 equation. This change means earlier eligibility for dialysis and transplant referrals for Black and African American patients, and it’s now the standard in U.S. labs.
What the Numbers Mean: CKD Stages
Doctors use eGFR ranges to classify kidney function into five stages of chronic kidney disease:
- Stage 1 (eGFR 90 or above): Normal filtering, but other signs of kidney damage may be present, such as protein in the urine.
- Stage 2 (eGFR 60 to 89): Mild loss of function. Often discovered incidentally on routine bloodwork.
- Stage 3a (eGFR 45 to 59): Mild to moderate loss. This is where many people first learn something is off.
- Stage 3b (eGFR 30 to 44): Moderate to severe loss. Symptoms become more likely at this point.
- Stage 4 (eGFR 15 to 29): Severe loss. Planning for possible dialysis or transplant typically begins here.
- Stage 5 (eGFR below 15): Kidney failure. The kidneys can no longer sustain life without treatment.
A single low reading doesn’t automatically mean CKD. Doctors generally look for a pattern of low results over at least three months before making that diagnosis.
Why Your eGFR Might Be Low
Diabetes is the leading cause of kidney damage worldwide. Persistently high blood sugar injures the small blood vessels inside the kidneys, gradually reducing their ability to filter. High blood pressure is the second most common cause, because it forces the kidneys to work under constant excess pressure that wears out those same filtering units over time. Together, these two conditions account for the majority of CKD cases.
Other causes include autoimmune diseases like lupus, recurring kidney infections, genetic conditions like polycystic kidney disease, and long-term use of certain over-the-counter pain relievers (particularly NSAIDs taken frequently over years). Heart disease and obesity also contribute to declining kidney function.
Temporary Reasons for a Low Reading
Not every low eGFR result reflects actual kidney damage. Because the test relies on creatinine levels, anything that raises creatinine in your blood will make your eGFR look worse than it really is. Common culprits include dehydration, eating large amounts of cooked meat before the test, taking creatine supplements, recent high-intensity exercise, and having a very muscular build. Certain medications, including trimethoprim (an antibiotic), ritonavir, and fenofibrate, can also raise creatinine without harming the kidneys.
If your doctor suspects one of these factors skewed the result, they may order a repeat test or request a cystatin C measurement, which is a different blood marker that isn’t affected by muscle mass or diet.
Normal Decline With Age
Kidney function naturally decreases as you get older, starting around your mid-30s. The average adult loses roughly 1 mL/min per year. In practical terms, a healthy 35-year-old might have an eGFR around 110, while a healthy 75-year-old typically lands around 80 to 85. This means an eGFR of 65 in a 78-year-old tells a different story than the same number in a 40-year-old. Your doctor interprets the result in the context of your age, trends over time, and whether there are other signs of kidney damage.
Symptoms at Different Stages
One of the tricky things about kidney disease is that it’s silent in its early stages. Most people with an eGFR between 60 and 89 feel completely normal. That’s why it’s often caught through routine blood tests rather than symptoms.
Once eGFR drops below 60 (Stage 3), symptoms can begin to surface, though many people still feel fine. Possible signs include fatigue, swelling in the hands or feet, dry or itchy skin, lower back pain, muscle cramps, trouble sleeping, restless legs, and changes in urination, either going more or less often than usual. Some people notice their urine looks foamy or darker than normal. These symptoms tend to become more pronounced and harder to ignore as eGFR falls below 30.
What Happens After a Low Result
A low eGFR on its own doesn’t give the full picture. Your doctor will typically order a urine albumin-to-creatinine ratio (uACR) test, which checks for protein leaking into your urine. Healthy kidneys keep protein in the blood, so finding it in urine is a direct marker of kidney damage. A uACR above 30 mg/g confirms that albumin is present and supports a CKD diagnosis. Values above 300 mg/g indicate more significant damage.
The combination of eGFR and uACR together determines both the stage and severity of kidney disease, and it guides how aggressively your doctor will want to manage it. You can expect repeat blood and urine tests over the following months to track whether your numbers are stable, improving, or declining.
Slowing Further Decline
If your eGFR is low due to actual kidney disease rather than a temporary cause, the goal shifts to preserving the function you still have. Kidney damage generally can’t be reversed, but the rate of decline can often be slowed considerably.
Blood pressure and blood sugar control are the two biggest levers. Keeping both in a healthy range reduces the ongoing stress on your kidneys. For people with diabetes, a class of medications called SGLT2 inhibitors has shown clear benefits for protecting kidney function, even though they may cause a small initial dip in eGFR that improves long-term outcomes.
Diet plays a meaningful role as well. The Dietary Guidelines for Americans recommend limiting sodium to no more than 2,300 milligrams per day, and many people with CKD need to go lower than that. Reducing sodium helps control blood pressure and decreases the workload on the kidneys. Protein intake is a balancing act: too much protein forces the kidneys to work harder to filter waste, but too little leads to malnutrition. Plant-based protein sources and lean meats tend to be easier on the kidneys than red meat and processed options. A dietitian who specializes in kidney health can help you find the right balance so you’re nourished without putting extra strain on your kidneys.
Staying physically active, maintaining a healthy weight, avoiding NSAIDs when possible, and not smoking all contribute to slower progression. Small, consistent changes in these areas add up over years of kidney health.