How ageing affects your kidneys

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As you age, your kidneys don’t always work as efficiently as they once did. 

The good news is that there are practical steps you can take to help keep them working well for as long as possible.

The natural ageing process

Your kidneys contain millions of tiny filtering units called nephrons that filter waste and excess fluid from your blood. “As you age, you gradually lose nephrons, and the remaining ones may not function as efficiently,” says Dr Sagen Naidoo, a physician at Mediclinic Louis Leipoldt.

“Blood flow to the kidneys also decreases over time, reducing their ability to filter waste products effectively. In addition, they become less responsive to hormones that regulate blood pressure and fluid balance.”

Key age-related changes

Dr Naidoo identifies several signs that your kidneys aren’t functioning optimally:

• Increased nighttime urination: “Ageing kidneys become less efficient at concentrating urine, so you may need to get up more frequently during the night to use the bathroom.” This can disrupt sleep patterns and increase dehydration risk.
• Slower medication processing: When kidney function slows, medicines stay in your system longer. “Slower elimination can lead to drug accumulation, especially with medications that you take multiple times daily. What starts as a safe dose can gradually build up to toxic levels over days or weeks.” Your dose may need to be adjusted. Some medicines – especially blood thinners and heart drugs – can build up in your body if your kidneys aren’t functioning well.
• Electrolyte imbalances: Older kidneys struggle more to maintain proper sodium and potassium levels, which affects heart function and blood pressure.
• Reduced thirst sensation: Older people often aren’t aware of feeling thirsty. “Ageing kidneys also can’t conserve water as effectively as before, creating a perfect storm for dehydration.”

Risk factors for kidney deterioration

Diabetes remains the leading cause of kidney disease. “High blood sugar levels damage the tiny blood vessels in your kidneys' filtering units, causing them to leak protein and gradually lose function,” says Dr Naidoo. This condition, called diabetic nephropathy, often develops silently over years without obvious symptoms.

“High blood pressure also forces your kidneys to work harder, potentially damaging the delicate filtering system,” he explains.

Prevention strategies

A few simple lifestyle changes can help protect your kidney health as you get older.

• Drink enough water. Your urine should be pale yellow or clear. If you have heart or kidney problems, ask your doctor how much fluid is right for you.
• Manage your blood pressure and blood sugar levels. “Regular monitoring and medication compliance, when prescribed, can prevent or slow kidney damage,” says Dr Gartrell. A heart-healthy diet low in sodium and processed foods supports both cardiovascular and kidney health.”
• Regular exercise like walking, swimming, or gardening improves circulation and helps maintain healthy blood pressure and weight.
• As you get older, regular health check-ups become more important. “Annual blood and urine tests can detect early signs of kidney problems before symptoms appear,” says Dr Naidoo. “Key indicators include elevated creatinine levels, protein in urine, or changes in estimated glomerular filtration rate (eGFR).”
• Watch for warning signs such as persistent swelling in legs or ankles, changes in urination patterns, ongoing tiredness, or difficulty controlling blood pressure. See your doctor if you notice any of these symptoms.

Protecting your kidneys as you age

While ageing can affect your kidney function, kidney disease isn’t inevitable. Regular check-ups, including blood and urine tests, can pick up problems early, when they’re easier to treat. “By staying proactive about your kidney health, maintaining a healthy lifestyle, and working closely with healthcare professionals, you can help preserve kidney function and maintain your quality of life as you age,” says Dr Naidoo.