{"content_id":"yjqcvrmv90","slug":"kidney-function-decline-aging-and-test-criteria","locale":"en","schema_type":"Article","category":"knowledge_base","category_name":"Knowledge Base","title":"Kidney Function Decline: Aging and Test Criteria","summary":"Aging affects kidney function, but the most common causes of chronic kidney disease in adults are diabetes and high blood pressure. This article explains the limits of research on nephron loss, how to interpret blood and urine tests, and management principles based on the patient's condition.","sponsorship_disclosure":null,"affiliate_disclosure":null,"commerce_disclosure":null,"author":{"name":"Injoys Editorial Team","url":"https://injoys.com/ko/about"},"key_points":["Age-related kidney changes and damage caused by disease must be assessed separately.","The age-group averages in the 2017 nephron study cannot be interpreted as an individual's rate of decline.","Kidney health is assessed using both estimated glomerular filtration rate and a urine albumin test.","If muscle mass is low, creatinine-based tests may overestimate kidney function.","The decision to start dialysis takes symptoms, test results, and other factors into account, not nephron count."],"content_markdown":"Aging is one factor that contributes to declining kidney function. However, the most common causes of chronic kidney disease in adults are diabetes and high blood pressure. A decline in function should not be considered normal simply because someone is older.\n\nThe diagnostic criteria are based on the KDIGO 2024 guideline, and the nephron figures are based on a study published in 2017.\n\n## Is aging the biggest cause of declining kidney function?\n\nIt is difficult to say that aging is the biggest cause of every decline in kidney function. Age-related changes must be distinguished from the causes of disease. NIDDK, the U.S. National Institute of Diabetes and Digestive and Kidney Diseases, identifies diabetes and high blood pressure as leading causes. This is based on [NIDDK’s guide to the causes of chronic kidney disease](https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/causes).\n\nPersistently high blood sugar can damage the kidneys’ filtering structures. High blood pressure can damage kidney blood vessels and filtering tissue. As kidney function worsens, blood pressure can also become harder to control.\n\nAn evaluation of the cause also checks for:\n\n- The possibility of glomerular disease or inherited kidney disease\n- Any previous acute kidney injury\n- Use of medications that could affect the kidneys\n- The possibility of a condition that blocks urine flow\n\n## What do nephrons do?\n\nNephrons are the basic units in the kidneys that filter blood and make urine. A nephron’s glomerulus is a small cluster of blood vessels that filters blood. Its tubule reabsorbs needed substances from what has been filtered. Through this process, waste and excess water leave the body in urine.\n\nThe kidneys regulate the balance of water and electrolytes. They also help regulate the body’s acidity. Kidney functions also include hormonal roles needed for blood pressure, red blood cell production, and bone health. The effects of declining function therefore extend beyond waste buildup. This is based on [NIDDK’s explanation of how the kidneys work](https://www.niddk.nih.gov/health-information/kidney-disease/kidneys-how-they-work).\n\n## Common misunderstandings about nephron loss figures\n\nAverage nephron counts by age cannot be used to calculate an individual’s kidney lifespan. A study published in 2017 compared healthy kidney donors. The researchers estimated nephron counts using CT scans and tissue examinations. The figures below are estimated averages for non-sclerotic glomeruli.\n\n| Age group in the study published in 2017 | Estimated average number of non-sclerotic glomeruli in one kidney |\n| --- | ---: |\n| 18~29 years | 990,661 |\n| 70~75 years | 520,410 |\n\nThe older comparison group in this study was 70~75 years old, not in their 60s. The results also did not come from following the same people from youth into old age. Therefore, they cannot establish the early 20s as the age when nephron loss begins for everyone. The source is [a study of aging and nephron numbers in healthy people](https://pubmed.ncbi.nlm.nih.gov/27401688/).\n\n| Common interpretation | What to distinguish when reading the study |\n| --- | --- |\n| People in their 60s necessarily have half as many nephrons as people in their 20s | Check the study’s age groups and differences between individuals |\n| Filtering function falls by the same percentage as nephron count | Nephron count and overall filtering function are different measures |\n| Average nephron loss can be used to calculate when dialysis will be needed | A comparison between groups cannot predict an individual’s course of disease |\n\n## Interpreting test results by circumstance\n\nBlood and urine test results must be considered together to assess kidney health. Estimated glomerular filtration rate, or eGFR, estimates how well the kidneys filter blood. The urine albumin-to-creatinine ratio, or UACR, assesses albumin leakage. Abnormal test results can appear early, even without symptoms. This is based on [NIDDK’s guide to kidney tests](https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/tests-diagnosis).\n\nThe KDIGO 2024 guideline calls for checking whether an abnormality persists for **at least 3 months**. Chronic kidney disease means an abnormality in kidney structure or function that affects health. The diagnostic criteria are in [Table 1 of the official KDIGO guideline](https://kdigo.org/wp-content/uploads/2024/03/KDIGO-2024-CKD-Guideline.pdf).\n\n| Test result or situation | Interpretation |\n| --- | --- |\n| eGFR less than 60 mL/min/1.73m² for at least 3 months | Meets a diagnostic criterion for chronic kidney disease |\n| UACR at least 30 mg/g for at least 3 months | Is a marker of kidney damage |\n| eGFR at least 60 mL/min/1.73m² | Other markers of damage, such as albuminuria, also need to be checked |\n| An abnormality found on the first test | Assess whether it persists and what caused it using previous results and repeat testing |\n\nThe 3 months are not a waiting period during which an abnormality should be left unaddressed. A sudden change should first be assessed for possible acute kidney injury. Even in older people, persistent abnormal test results should not be attributed to aging alone.\n\n## Does lower muscle mass change how test results are interpreted?\n\nWhen muscle mass is low, kidney function estimated from creatinine may appear higher than it really is. Creatinine is a waste product made by muscles. As muscle mass decreases with age, creatinine production may also decrease. Creatinine levels alone can therefore make kidney health difficult to assess.\n\nA cystatin C test may help in this situation. Cystatin C is another blood marker used to estimate kidney filtering function. However, factors such as thyroid disease and steroid use can also affect it. Consult a healthcare professional about test selection, using [National Kidney Foundation’s guide to cystatin C](https://www.kidney.org/kidney-topics/cystatin-c) as a reference.\n\nTell your healthcare professional if you have recently lost a substantial amount of weight or muscle. Bring previous test results as well. Explaining changes in your results alongside changes in how you feel can help with interpretation.\n\n## Managing your current condition\n\nA management plan should be based on the underlying condition and test results rather than age. If you have diabetes, check your blood sugar target. If you have high blood pressure, review how well it is controlled. The interval between routine tests varies with kidney health.\n\n| Current situation | What to discuss at an appointment |\n| --- | --- |\n| Diabetes | Blood sugar management and a kidney testing plan |\n| High blood pressure | Blood pressure target, medications, and kidney test results |\n| A family history of heart or kidney disease | Whether kidney tests are needed and how often |\n| A diagnosis of chronic kidney disease | Changes in eGFR and albuminuria, and response to treatment |\n| Weight loss or reduced food intake | Nutritional status and whether dietary restrictions are appropriate |\n\nPrepare for your appointment in this order:\n\n1. Gather previous blood and urine test results and the dates of the tests.\n2. Make a list of medications and dietary supplements you take.\n3. Organize your blood pressure records and note recent changes in how you feel.\n4. Check when your next tests should be and what dietary changes you need to make.\n\nNot smoking and getting physical activity suited to your condition are also part of management. Take prescribed medications as directed. If your test results have changed, tell your healthcare professional rather than stopping a medication on your own. This is based on [NIDDK’s guide to managing chronic kidney disease](https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/managing).\n\n## Mistakes to avoid with food and medications\n\nA kidney diet should be adjusted to your test results and nutritional status. The same dietary restrictions do not apply to everyone. Cutting protein too much can lead to poor nutrition. Protein needs may differ during dialysis.\n\n| Common choice | What to check |\n| --- | --- |\n| Drinking a lot of water to clean the kidneys | Whether fluid intake needs to be adjusted based on swelling and kidney function |\n| Restricting all vegetables and fruit | Blood potassium levels and whether restrictions are actually needed |\n| Replacing regular salt with low-sodium salt | Whether it contains potassium chloride |\n| Greatly reducing protein foods such as meat and beans | An appropriate intake based on nutritional status and whether you are on dialysis |\n| Frequently eating processed foods | Sodium content and phosphate additives |\n\nThe dietary advice is based on [NIDDK’s nutrition guide for adults with chronic kidney disease](https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/healthy-eating-adults-chronic-kidney-disease).\n\nNonsteroidal anti-inflammatory drugs such as ibuprofen can damage the kidneys. The risk may be greater if you are dehydrated. Ask a pharmacist to check the ingredients when choosing a pain reliever or cold medicine. This is based on [NIDDK’s medication safety guide](https://www.niddk.nih.gov/health-information/kidney-disease/keeping-kidneys-safe).\n\n## When is dialysis needed?\n\nDialysis is not started at the point when all nephrons are gone. Symptoms, abnormal test results, and filtering function are assessed together. Quality of life and treatment preferences are also considered. This principle appears in the [KDIGO 2024 guideline’s criteria for starting dialysis](https://kdigo.org/wp-content/uploads/2024/03/KDIGO-2024-CKD-Guideline.pdf).\n\nWhen kidney function falls substantially, waste and fluid can build up. The condition in which this causes symptoms is called uremia. Treatments that replace kidney function include hemodialysis, peritoneal dialysis, and kidney transplantation. Consult a healthcare professional about treatment options, using [NIDDK’s guide to kidney failure](https://www.niddk.nih.gov/health-information/kidney-disease/kidney-failure/what-is-kidney-failure) as a reference.\n\n## Is a sudden decline also due to aging?\n\nA sudden decline in kidney function should not be attributed to aging alone. Dehydration, infection, or a blockage in the urinary tract can cause acute kidney injury. Function may recover after the cause is treated. In some cases, damage may remain.\n\nSeek prompt medical care if any of these symptoms appear:\n\n- A marked decrease in urine output compared with usual\n- Persistent vomiting with suspected dehydration\n- Leg swelling or shortness of breath\n- Confusion or severe drowsiness\n\nAcute kidney injury may also occur without obvious symptoms. Symptoms alone cannot establish the condition of your kidneys. If an abnormality is suspected, testing is needed to check it. This is based on [NHS’s guide to acute kidney injury](https://www.nhs.uk/conditions/acute-kidney-injury/).","content_html":"\u003cp\u003eAging is one factor that contributes to declining kidney function. However, the most common causes of chronic kidney disease in adults are diabetes and high blood pressure. A decline in function should not be considered normal simply because someone is older.\u003c/p\u003e\n\u003cp\u003eThe diagnostic criteria are based on the KDIGO 2024 guideline, and the nephron figures are based on a study published in 2017.\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#is-aging-the-biggest-cause-of-declining-kidney-function\" class=\"anchor\" id=\"is-aging-the-biggest-cause-of-declining-kidney-function\"\u003e\u003c/a\u003eIs aging the biggest cause of declining kidney function?\u003c/h2\u003e\n\u003cp\u003eIt is difficult to say that aging is the biggest cause of every decline in kidney function. Age-related changes must be distinguished from the causes of disease. NIDDK, the U.S. National Institute of Diabetes and Digestive and Kidney Diseases, identifies diabetes and high blood pressure as leading causes. This is based on \u003ca href=\"https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/causes\"\u003eNIDDK’s guide to the causes of chronic kidney disease\u003c/a\u003e.\u003c/p\u003e\n\u003cp\u003ePersistently high blood sugar can damage the kidneys’ filtering structures. High blood pressure can damage kidney blood vessels and filtering tissue. As kidney function worsens, blood pressure can also become harder to control.\u003c/p\u003e\n\u003cp\u003eAn evaluation of the cause also checks for:\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003eThe possibility of glomerular disease or inherited kidney disease\u003c/li\u003e\n\u003cli\u003eAny previous acute kidney injury\u003c/li\u003e\n\u003cli\u003eUse of medications that could affect the kidneys\u003c/li\u003e\n\u003cli\u003eThe possibility of a condition that blocks urine flow\u003c/li\u003e\n\u003c/ul\u003e\n\u003ch2\u003e\n\u003ca href=\"#what-do-nephrons-do\" class=\"anchor\" id=\"what-do-nephrons-do\"\u003e\u003c/a\u003eWhat do nephrons do?\u003c/h2\u003e\n\u003cp\u003eNephrons are the basic units in the kidneys that filter blood and make urine. A nephron’s glomerulus is a small cluster of blood vessels that filters blood. Its tubule reabsorbs needed substances from what has been filtered. Through this process, waste and excess water leave the body in urine.\u003c/p\u003e\n\u003cp\u003eThe kidneys regulate the balance of water and electrolytes. They also help regulate the body’s acidity. Kidney functions also include hormonal roles needed for blood pressure, red blood cell production, and bone health. The effects of declining function therefore extend beyond waste buildup. This is based on \u003ca href=\"https://www.niddk.nih.gov/health-information/kidney-disease/kidneys-how-they-work\"\u003eNIDDK’s explanation of how the kidneys work\u003c/a\u003e.\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#common-misunderstandings-about-nephron-loss-figures\" class=\"anchor\" id=\"common-misunderstandings-about-nephron-loss-figures\"\u003e\u003c/a\u003eCommon misunderstandings about nephron loss figures\u003c/h2\u003e\n\u003cp\u003eAverage nephron counts by age cannot be used to calculate an individual’s kidney lifespan. A study published in 2017 compared healthy kidney donors. The researchers estimated nephron counts using CT scans and tissue examinations. The figures below are estimated averages for non-sclerotic glomeruli.\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eAge group in the study published in 2017\u003c/th\u003e\n\u003cth\u003eEstimated average number of non-sclerotic glomeruli in one kidney\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Age group in the study published in 2017\"\u003e18~29 years\u003c/td\u003e\n\u003ctd data-label=\"Estimated average number of non-sclerotic glomeruli in one kidney\"\u003e990,661\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Age group in the study published in 2017\"\u003e70~75 years\u003c/td\u003e\n\u003ctd data-label=\"Estimated average number of non-sclerotic glomeruli in one kidney\"\u003e520,410\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003eThe older comparison group in this study was 70~75 years old, not in their 60s. The results also did not come from following the same people from youth into old age. Therefore, they cannot establish the early 20s as the age when nephron loss begins for everyone. The source is \u003ca href=\"https://pubmed.ncbi.nlm.nih.gov/27401688/\"\u003ea study of aging and nephron numbers in healthy people\u003c/a\u003e.\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eCommon interpretation\u003c/th\u003e\n\u003cth\u003eWhat to distinguish when reading the study\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Common interpretation\"\u003ePeople in their 60s necessarily have half as many nephrons as people in their 20s\u003c/td\u003e\n\u003ctd data-label=\"What to distinguish when reading the study\"\u003eCheck the study’s age groups and differences between individuals\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Common interpretation\"\u003eFiltering function falls by the same percentage as nephron count\u003c/td\u003e\n\u003ctd data-label=\"What to distinguish when reading the study\"\u003eNephron count and overall filtering function are different measures\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Common interpretation\"\u003eAverage nephron loss can be used to calculate when dialysis will be needed\u003c/td\u003e\n\u003ctd data-label=\"What to distinguish when reading the study\"\u003eA comparison between groups cannot predict an individual’s course of disease\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003ch2\u003e\n\u003ca href=\"#interpreting-test-results-by-circumstance\" class=\"anchor\" id=\"interpreting-test-results-by-circumstance\"\u003e\u003c/a\u003eInterpreting test results by circumstance\u003c/h2\u003e\n\u003cp\u003eBlood and urine test results must be considered together to assess kidney health. Estimated glomerular filtration rate, or eGFR, estimates how well the kidneys filter blood. The urine albumin-to-creatinine ratio, or UACR, assesses albumin leakage. Abnormal test results can appear early, even without symptoms. This is based on \u003ca href=\"https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/tests-diagnosis\"\u003eNIDDK’s guide to kidney tests\u003c/a\u003e.\u003c/p\u003e\n\u003cp\u003eThe KDIGO 2024 guideline calls for checking whether an abnormality persists for \u003cstrong\u003eat least 3 months\u003c/strong\u003e. Chronic kidney disease means an abnormality in kidney structure or function that affects health. The diagnostic criteria are in \u003ca href=\"https://kdigo.org/wp-content/uploads/2024/03/KDIGO-2024-CKD-Guideline.pdf\"\u003eTable 1 of the official KDIGO guideline\u003c/a\u003e.\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eTest result or situation\u003c/th\u003e\n\u003cth\u003eInterpretation\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Test result or situation\"\u003eeGFR less than 60 mL/min/1.73m² for at least 3 months\u003c/td\u003e\n\u003ctd data-label=\"Interpretation\"\u003eMeets a diagnostic criterion for chronic kidney disease\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Test result or situation\"\u003eUACR at least 30 mg/g for at least 3 months\u003c/td\u003e\n\u003ctd data-label=\"Interpretation\"\u003eIs a marker of kidney damage\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Test result or situation\"\u003eeGFR at least 60 mL/min/1.73m²\u003c/td\u003e\n\u003ctd data-label=\"Interpretation\"\u003eOther markers of damage, such as albuminuria, also need to be checked\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Test result or situation\"\u003eAn abnormality found on the first test\u003c/td\u003e\n\u003ctd data-label=\"Interpretation\"\u003eAssess whether it persists and what caused it using previous results and repeat testing\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003eThe 3 months are not a waiting period during which an abnormality should be left unaddressed. A sudden change should first be assessed for possible acute kidney injury. Even in older people, persistent abnormal test results should not be attributed to aging alone.\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#does-lower-muscle-mass-change-how-test-results-are-interpreted\" class=\"anchor\" id=\"does-lower-muscle-mass-change-how-test-results-are-interpreted\"\u003e\u003c/a\u003eDoes lower muscle mass change how test results are interpreted?\u003c/h2\u003e\n\u003cp\u003eWhen muscle mass is low, kidney function estimated from creatinine may appear higher than it really is. Creatinine is a waste product made by muscles. As muscle mass decreases with age, creatinine production may also decrease. Creatinine levels alone can therefore make kidney health difficult to assess.\u003c/p\u003e\n\u003cp\u003eA cystatin C test may help in this situation. Cystatin C is another blood marker used to estimate kidney filtering function. However, factors such as thyroid disease and steroid use can also affect it. Consult a healthcare professional about test selection, using \u003ca href=\"https://www.kidney.org/kidney-topics/cystatin-c\"\u003eNational Kidney Foundation’s guide to cystatin C\u003c/a\u003e as a reference.\u003c/p\u003e\n\u003cp\u003eTell your healthcare professional if you have recently lost a substantial amount of weight or muscle. Bring previous test results as well. Explaining changes in your results alongside changes in how you feel can help with interpretation.\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#managing-your-current-condition\" class=\"anchor\" id=\"managing-your-current-condition\"\u003e\u003c/a\u003eManaging your current condition\u003c/h2\u003e\n\u003cp\u003eA management plan should be based on the underlying condition and test results rather than age. If you have diabetes, check your blood sugar target. If you have high blood pressure, review how well it is controlled. The interval between routine tests varies with kidney health.\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eCurrent situation\u003c/th\u003e\n\u003cth\u003eWhat to discuss at an appointment\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Current situation\"\u003eDiabetes\u003c/td\u003e\n\u003ctd data-label=\"What to discuss at an appointment\"\u003eBlood sugar management and a kidney testing plan\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Current situation\"\u003eHigh blood pressure\u003c/td\u003e\n\u003ctd data-label=\"What to discuss at an appointment\"\u003eBlood pressure target, medications, and kidney test results\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Current situation\"\u003eA family history of heart or kidney disease\u003c/td\u003e\n\u003ctd data-label=\"What to discuss at an appointment\"\u003eWhether kidney tests are needed and how often\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Current situation\"\u003eA diagnosis of chronic kidney disease\u003c/td\u003e\n\u003ctd data-label=\"What to discuss at an appointment\"\u003eChanges in eGFR and albuminuria, and response to treatment\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Current situation\"\u003eWeight loss or reduced food intake\u003c/td\u003e\n\u003ctd data-label=\"What to discuss at an appointment\"\u003eNutritional status and whether dietary restrictions are appropriate\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003ePrepare for your appointment in this order:\u003c/p\u003e\n\u003col\u003e\n\u003cli\u003eGather previous blood and urine test results and the dates of the tests.\u003c/li\u003e\n\u003cli\u003eMake a list of medications and dietary supplements you take.\u003c/li\u003e\n\u003cli\u003eOrganize your blood pressure records and note recent changes in how you feel.\u003c/li\u003e\n\u003cli\u003eCheck when your next tests should be and what dietary changes you need to make.\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eNot smoking and getting physical activity suited to your condition are also part of management. Take prescribed medications as directed. If your test results have changed, tell your healthcare professional rather than stopping a medication on your own. This is based on \u003ca href=\"https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/managing\"\u003eNIDDK’s guide to managing chronic kidney disease\u003c/a\u003e.\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#mistakes-to-avoid-with-food-and-medications\" class=\"anchor\" id=\"mistakes-to-avoid-with-food-and-medications\"\u003e\u003c/a\u003eMistakes to avoid with food and medications\u003c/h2\u003e\n\u003cp\u003eA kidney diet should be adjusted to your test results and nutritional status. The same dietary restrictions do not apply to everyone. Cutting protein too much can lead to poor nutrition. Protein needs may differ during dialysis.\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eCommon choice\u003c/th\u003e\n\u003cth\u003eWhat to check\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Common choice\"\u003eDrinking a lot of water to clean the kidneys\u003c/td\u003e\n\u003ctd data-label=\"What to check\"\u003eWhether fluid intake needs to be adjusted based on swelling and kidney function\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Common choice\"\u003eRestricting all vegetables and fruit\u003c/td\u003e\n\u003ctd data-label=\"What to check\"\u003eBlood potassium levels and whether restrictions are actually needed\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Common choice\"\u003eReplacing regular salt with low-sodium salt\u003c/td\u003e\n\u003ctd data-label=\"What to check\"\u003eWhether it contains potassium chloride\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Common choice\"\u003eGreatly reducing protein foods such as meat and beans\u003c/td\u003e\n\u003ctd data-label=\"What to check\"\u003eAn appropriate intake based on nutritional status and whether you are on dialysis\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Common choice\"\u003eFrequently eating processed foods\u003c/td\u003e\n\u003ctd data-label=\"What to check\"\u003eSodium content and phosphate additives\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003eThe dietary advice is based on \u003ca href=\"https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/healthy-eating-adults-chronic-kidney-disease\"\u003eNIDDK’s nutrition guide for adults with chronic kidney disease\u003c/a\u003e.\u003c/p\u003e\n\u003cp\u003eNonsteroidal anti-inflammatory drugs such as ibuprofen can damage the kidneys. The risk may be greater if you are dehydrated. Ask a pharmacist to check the ingredients when choosing a pain reliever or cold medicine. This is based on \u003ca href=\"https://www.niddk.nih.gov/health-information/kidney-disease/keeping-kidneys-safe\"\u003eNIDDK’s medication safety guide\u003c/a\u003e.\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#when-is-dialysis-needed\" class=\"anchor\" id=\"when-is-dialysis-needed\"\u003e\u003c/a\u003eWhen is dialysis needed?\u003c/h2\u003e\n\u003cp\u003eDialysis is not started at the point when all nephrons are gone. Symptoms, abnormal test results, and filtering function are assessed together. Quality of life and treatment preferences are also considered. This principle appears in the \u003ca href=\"https://kdigo.org/wp-content/uploads/2024/03/KDIGO-2024-CKD-Guideline.pdf\"\u003eKDIGO 2024 guideline’s criteria for starting dialysis\u003c/a\u003e.\u003c/p\u003e\n\u003cp\u003eWhen kidney function falls substantially, waste and fluid can build up. The condition in which this causes symptoms is called uremia. Treatments that replace kidney function include hemodialysis, peritoneal dialysis, and kidney transplantation. Consult a healthcare professional about treatment options, using \u003ca href=\"https://www.niddk.nih.gov/health-information/kidney-disease/kidney-failure/what-is-kidney-failure\"\u003eNIDDK’s guide to kidney failure\u003c/a\u003e as a reference.\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#is-a-sudden-decline-also-due-to-aging\" class=\"anchor\" id=\"is-a-sudden-decline-also-due-to-aging\"\u003e\u003c/a\u003eIs a sudden decline also due to aging?\u003c/h2\u003e\n\u003cp\u003eA sudden decline in kidney function should not be attributed to aging alone. Dehydration, infection, or a blockage in the urinary tract can cause acute kidney injury. Function may recover after the cause is treated. In some cases, damage may remain.\u003c/p\u003e\n\u003cp\u003eSeek prompt medical care if any of these symptoms appear:\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003eA marked decrease in urine output compared with usual\u003c/li\u003e\n\u003cli\u003ePersistent vomiting with suspected dehydration\u003c/li\u003e\n\u003cli\u003eLeg swelling or shortness of breath\u003c/li\u003e\n\u003cli\u003eConfusion or severe drowsiness\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eAcute kidney injury may also occur without obvious symptoms. Symptoms alone cannot establish the condition of your kidneys. If an abnormality is suspected, testing is needed to check it. This is based on \u003ca href=\"https://www.nhs.uk/conditions/acute-kidney-injury/\"\u003eNHS’s guide to acute kidney injury\u003c/a\u003e.\u003c/p\u003e\n","tags":["Kidney health","Chronic kidney disease","Dialysis","Health Screening","Kidney function","Healthy aging"],"faqs":[{"question":"Does getting older inevitably lead to chronic kidney disease?","answer":"Age alone is not enough to diagnose chronic kidney disease. Abnormalities in kidney structure or function, and how long they have been present, must be confirmed."},{"question":"What is the most common cause of reduced kidney function?","answer":"NIDDK identifies diabetes and high blood pressure as the most common causes of chronic kidney disease in adults. An individual's cause must be determined from their medical history and test results."},{"question":"Do people in their 60s have half as many nephrons as people in their 20s?","answer":"That figure cannot be applied to everyone in their 60s. The age groups compared in a 2017 study were 18 to 29 and 70 to 75. The study also did not measure a person's decline over their lifetime."},{"question":"Does nephron loss begin precisely in the early 20s?","answer":"The age-group comparison studies reviewed cannot, on their own, determine when nephron loss begins in an individual. Average differences between age groups must be distinguished from changes within an individual."},{"question":"Do I need kidney tests even if I have no symptoms?","answer":"Early kidney disease may have no symptoms. If you have diabetes, high blood pressure, heart disease, or a family history of kidney failure, discuss a testing plan with your healthcare provider."},{"question":"If my blood test results are normal, can I skip the urine test?","answer":"Albumin can be detected in urine even when filtration function is preserved. eGFR and urine albumin tests provide different information."},{"question":"Does a low creatinine level mean my kidneys are healthy?","answer":"Low muscle mass can also result in a low creatinine level. If you have recently lost muscle mass, that should be taken into account when interpreting your test results. A cystatin C test may be considered if needed."},{"question":"Should I drink a lot of water for my kidneys?","answer":"Drinking a lot of water is not appropriate for every kidney condition. If reduced kidney function makes it difficult to excrete fluid, you may need to adjust how much you drink."},{"question":"If my kidney function declines, should I cut back on both protein and fruit?","answer":"Rather than restricting foods across the board, adjust your diet based on test results and nutritional status. Cutting back too much on protein can lead to poor nutrition. Potassium restrictions are determined based on blood levels and other factors."},{"question":"Do all my nephrons have to be gone before I start dialysis?","answer":"The decision to start dialysis is not based on the number of nephrons. Symptoms, test results, filtration function, and treatment preferences are assessed together."},{"question":"Does kidney function always decline slowly?","answer":"Acute kidney injury caused by dehydration or infection can make kidney function worsen suddenly. If you develop symptoms such as reduced urine output or shortness of breath, seek medical care promptly."}],"sources":[{"url":"https://kdigo.org/wp-content/uploads/2024/03/KDIGO-2024-CKD-Guideline.pdf","title":"KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease","type":"source"},{"url":"https://pubmed.ncbi.nlm.nih.gov/27401688/","title":"The Substantial Loss of Nephrons in Healthy Human Kidneys with Aging, 2017","type":"data_point"},{"url":"https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/causes","title":"NIDDK: Causes of Chronic Kidney Disease in Adults","type":"source"},{"url":"https://www.niddk.nih.gov/health-information/kidney-disease/kidneys-how-they-work","title":"NIDDK: Your Kidneys \u000026 How They Work","type":"source"},{"url":"https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/tests-diagnosis","title":"NIDDK: Chronic Kidney Disease Tests \u000026 Diagnosis","type":"source"},{"url":"https://www.kidney.org/kidney-topics/cystatin-c","title":"National Kidney Foundation: Cystatin C","type":"source"},{"url":"https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/managing","title":"NIDDK: Managing Chronic Kidney Disease","type":"source"},{"url":"https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/healthy-eating-adults-chronic-kidney-disease","title":"NIDDK: Healthy Eating for Adults with Chronic Kidney Disease","type":"source"},{"url":"https://www.niddk.nih.gov/health-information/kidney-disease/keeping-kidneys-safe","title":"NIDDK: Keeping Kidneys Safe: Smart Choices about Medicines","type":"source"},{"url":"https://www.niddk.nih.gov/health-information/kidney-disease/kidney-failure/what-is-kidney-failure","title":"NIDDK: What is Kidney Failure?","type":"source"},{"url":"https://www.nhs.uk/conditions/acute-kidney-injury/","title":"NHS: Acute kidney injury, reviewed March 11, 2026","type":"source"}],"images":[{"id":1779,"url":"https://injoys.com/rails/active_storage/blobs/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Mjc0MDIsInB1ciI6ImJsb2JfaWQifX0=--225931bfcb79d2347716207e881ca76ace3bbeb4/ai-49dad1ea.webp","is_representative":true,"generation_method":"ai_photo","license":"ai_generated","mime_type":"image/webp","width":1536,"height":1024,"translations":{"ko":{"alt":"진료실에서 혈압 커프를 찬 노인이 의료진과 대화하고, 옆 쟁반에 혈액 검체와 소변 검체가 놓여 있다.","caption":"콩팥 상태는 추정 사구체여과율과 소변 알부민 검사로 함께 평가합니다.","description":null},"en":{"alt":"An older man wearing a blood pressure cuff speaks with a clinician; blood and urine samples sit on a nearby tray.","caption":"Kidney health is assessed using both estimated filtration rate and urine albumin tests.","description":null},"ja":{"alt":"診察室で血圧計のカフを巻いた高齢男性が医療者と話し、そばに血液と尿の検体が置かれている。","caption":"腎臓の状態は推算糸球体濾過量と尿中アルブミン検査を併せて評価します。","description":null},"es":{"alt":"Un hombre mayor con un manguito de presión arterial habla con una profesional de salud; hay muestras de sangre y orina cerca.","caption":"La salud renal se evalúa con la tasa de filtración estimada y una prueba de albúmina en orina.","description":null},"id":{"alt":"Pria lanjut usia memakai manset tekanan darah sambil berbicara dengan tenaga medis; sampel darah dan urine ada di dekatnya.","caption":"Kondisi ginjal dinilai dengan laju filtrasi perkiraan dan pemeriksaan albumin urine.","description":null},"pt":{"alt":"Um homem idoso com manguito de pressão no braço conversa com uma profissional de saúde; há amostras de sangue e urina ao lado.","caption":"A saúde dos rins é avaliada pela taxa de filtração estimada e pelo exame de albumina na urina.","description":null},"zh-hant":{"alt":"診間裡，一名手臂戴著血壓袖帶的年長男子與醫護人員交談，旁邊放著血液和尿液檢體。","caption":"腎臟狀態須結合估算腎絲球過濾率與尿液白蛋白檢查評估。","description":null},"de":{"alt":"Ein älterer Mann mit Blutdruckmanschette spricht mit einer medizinischen Fachkraft; Blut- und Urinproben stehen daneben.","caption":"Der Zustand der Nieren wird anhand der geschätzten Filtrationsrate und eines Urin-Albumintests beurteilt.","description":null}}},{"id":1780,"url":"https://injoys.com/rails/active_storage/blobs/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Mjc0MDgsInB1ciI6ImJsb2JfaWQifX0=--927a6f56dce26a371dbad630f8b348892106196e/ai-34af3d9a.webp","is_representative":false,"generation_method":"ai_semi","license":"ai_generated","mime_type":"image/webp","width":1536,"height":1024,"translations":{"ko":{"alt":"약국에서 약사가 계산대 위 약 상자를 가리키며 나이 든 여성에게 설명한다.","caption":"약 복용 여부는 콩팥 상태를 고려해 판단해야 합니다.","description":null},"en":{"alt":"A pharmacist points to a medicine box on the counter while speaking with an older woman.","caption":"Decisions about taking medicine should take kidney health into account.","description":null},"ja":{"alt":"薬局で薬剤師がカウンターの薬箱を指しながら、年配の女性に説明している。","caption":"薬を服用するかどうかは、腎臓の状態を考慮して判断する必要があります。","description":null},"es":{"alt":"Un farmacéutico señala una caja de medicamento sobre el mostrador mientras habla con una mujer mayor.","caption":"La decisión de tomar un medicamento debe tener en cuenta el estado de los riñones.","description":null},"id":{"alt":"Apoteker menunjuk kotak obat di meja sambil berbicara dengan seorang perempuan lansia.","caption":"Keputusan untuk minum obat perlu mempertimbangkan kondisi ginjal.","description":null},"pt":{"alt":"Um farmacêutico aponta para uma caixa de medicamento no balcão enquanto conversa com uma mulher idosa.","caption":"A decisão de tomar um medicamento deve considerar a condição dos rins.","description":null},"zh-hant":{"alt":"藥師指著櫃檯上的藥盒，向一位年長女性說明。","caption":"是否服藥應考量腎臟的狀況。","description":null},"de":{"alt":"Ein Apotheker zeigt auf eine Medikamentenschachtel auf dem Tresen und spricht mit einer älteren Frau.","caption":"Bei der Entscheidung über die Einnahme von Medikamenten sollte der Zustand der Nieren berücksichtigt werden.","description":null}}}],"published_at":"2026-10-12T10:16:19+09:00","updated_at":"2026-10-12T10:16:19+09:00","license":"cc_by","translation_status":"reviewed","available_locales":["ko","en","ja","es"],"data_locales":["ko","en","ja","es","id","pt","zh-hant","de"],"url":"https://injoys.com/en/articles/kidney-function-decline-aging-and-test-criteria"}