Creatinine Clearance: Biomarker of Health & Longevity

Photo of nephrons by eLife Journal.

What lab tests can signal signs of longevity?
The Dunedin longitudinal study showed that research participants with higher creatinine clearance levels had better health overall.
Research shows that kidney function does slow down a little as we age.
However, not every older adult is destined for kidney dialysis.
This post is part of a series on biomarkers of health and longevity.
Monitoring kidney function is important.
[Note: This post does not offer medical advice; its purpose is only to increase awareness. If you have any concerns about your kidney health, please see a licensed medical professional.]
Sometime, people with diminishing kidney function show symptoms, which may include itching, loss of appetite, vomiting, weakness and flu-like symptoms.
Other people can have slowing kidney function without visible symptoms. One of several tests of the urine or blood can be vital to maintaining kidney function.
One such test is creatinine clearance.
What Is Creatinine and How Does the Body Dispose of It?
Creatinine is a waste product from normal breakdown of muscle tissue.  The kidneys filter creatinine out of the blood within the nephrons and dispose of creatinine through the urine.
Here is a 3 minute video that describes kidney function.  Listen for "creatinine" in the list of waste products:

This creatinine clearance test requires that urine be collected over a 24 hour period and submitted to a lab. Healthy levels fall somewhere in the neighborhood of 80 to 120. This number reflects the glomural filtration level (GFL).
What constitutes a healthy level depends on the amount of muscle a person has, their body size, their activity level and their medications.
According to the National Kidney Foundation, people in their 20s on the average have a GFL of 116; people 70 and over on the average have a GFL of 75. Dialysis is usually not required unless the GFL falls below 15.
Tips for Kidney Health
Although there can be a variety of causes of waning kidney function (diabetes being the most common), these are some suggestions for maintaining healthy kidneys:

• Healthy diet
• Regular exercise
• Proper blood sugar levels
• Proper blood pressure
• Adequate fluid intake
• Smoking cessation
• Limited over-the-counter drugs (such as acetaminophen), which can damage kidneys

Related:
18 Biomarkers of Health and Longevity
Age-related Risks for Dehydration National Diabetes Month
Nutrition for Our Age