Normal eGFR in Your 40s
Typical eGFR in your 40s and what counts as normal.
Medically reviewed by Dr. Rishi Kumar Kafle, MBBS, MD, FASN. Last reviewed October 2026.
A typical eGFR for an adult in their 40s is around 99 mL/min/1.73m². eGFR declines gradually with age, by roughly 1 mL/min per year after about age 40, so a lower value can still be normal for your age.
What an eGFR Result Means in Your 40s
By midlife the gentle, expected decline in filtration is under way, and lifestyle and cardiovascular risk factors begin to affect the kidneys. An eGFR a little below the youthful peak is common and usually benign. Even so, this is the decade where blood-pressure control, blood-glucose management, and a check for protein in the urine bring the largest long-term benefit. Catching and treating these drivers now keeps a normal-for-age eGFR from sliding into chronic kidney disease later.
Why eGFR Falls With Age
eGFR falls with age because the kidneys themselves change structurally over time. From early adulthood the kidneys gradually lose functioning nephrons, blood flow to the kidneys decreases, and the glomeruli filter a little less each year. In someone in their 40s with no diabetes, high blood pressure, or protein in the urine, an eGFR modestly below the youthful norm usually reflects this normal ageing rather than disease. This is also why the CKD threshold of 60 is read in context: the same value can be reassuring in an older adult and a warning sign in a young one.
When a Value Is a Concern
An eGFR under 60 mL/min/1.73m² sustained for three months indicates chronic kidney disease, regardless of age, and what matters most is the trend. A steady value is reassuring; a figure that is falling faster than the roughly 1 mL/min a year expected with ageing, or that comes with albuminuria, deserves attention. For an adult in their 40s, pair the eGFR with a urine albumin test, a blood-pressure check, and a review of any medicines that need renal dose adjustment. See what a low eGFR means and the full normal eGFR by age table.
How to Read Your Own Result at 40s
Compare your eGFR with the typical figure for your 40s above. Then weigh three things more heavily than the single number: whether it is stable or falling, whether there is albumin in the urine, and whether you have diabetes or high blood pressure. Two people in their 40s with the same eGFR can have very different outlooks depending on those factors. Because the estimate comes from a single serum creatinine, a result near the boundary is worth repeating before drawing conclusions. For the underlying method and how it differs from creatinine clearance used in dosing, see the CKD-EPI 2021 equation and CrCl vs eGFR. If your medicines need adjusting as filtration changes, your clinician will usually base the dose on a Cockcroft-Gault creatinine clearance rather than the eGFR shown here.