How Does Kidney Function Decline with Age and How Can It Be Preserved?

The short answer

Glomerular filtration rate (GFR) — the primary measure of kidney function — declines by approximately 0.75–1% per year after age 40 as a normal aging process. This means that a 70-year-old has approximately 30% lower kidney function than at age 40. Chronic kidney disease (CKD, GFR <60 mL/min/1.73m²) affects 38% of adults over 65 and is associated with significantly higher cardiovascular mortality. The rate of decline is substantially modifiable.

What the evidence actually shows

Lindeman et al. (1985) established the normal rate of GFR decline with age in a longitudinal study. Coresh et al. (2007) in JAMA, using NHANES data, found that CKD affects approximately 13% of the US adult population and 38% of those over 65. The primary drivers of accelerated kidney function decline are hypertension (which damages glomerular capillaries), diabetes (which causes diabetic nephropathy), and NSAIDs (which reduce renal blood flow). MedlinePlus notes that kidney disease often has no symptoms until it is advanced, making regular monitoring important for at-risk individuals.

"Chronic kidney disease affects approximately 38% of adults over 65 and is associated with significantly higher cardiovascular mortality."

— Coresh et al., JAMA 2007

What the major health authorities say

MedlinePlus and the NIH identify CKD as a major public health concern and recommend regular kidney function testing (eGFR and urine albumin-to-creatinine ratio) for at-risk individuals (those with diabetes, hypertension, or family history of kidney disease). The NIA recommends blood pressure control, diabetes management, and avoiding nephrotoxic medications as the primary strategies for preserving kidney function with age.

Practical implications

The most impactful strategies for preserving kidney function are: controlling blood pressure to below 130/80 mmHg; managing diabetes with tight glycaemic control; avoiding NSAIDs (ibuprofen, naproxen) for regular pain management — paracetamol/acetaminophen is safer for the kidneys; staying well hydrated; and avoiding unnecessary contrast dye procedures. ACE inhibitors and ARBs have specific kidney-protective effects in patients with diabetic nephropathy or proteinuria. Regular eGFR testing (annually for those with risk factors) allows early detection of decline.

Where reasonable people still disagree

• Whether high protein intake (>1.5g/kg/day) accelerates kidney function decline in healthy older adults without pre-existing CKD.
• The optimal blood pressure target for patients with CKD — whether aggressive lowering to <120/80 mmHg provides additional kidney protection beyond <130/80 mmHg.
• Whether SGLT-2 inhibitors (empagliflozin, dapagliflozin) should be used for kidney protection in all patients with CKD, or only those with diabetes.