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.

Nevertheless, 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 and dispose of creatinine through the urine.  More specifically, the nephrons within the kidney do the filtering. See the beautiful photo above for a digital image of just two of the approximately million nephrons of the kidney.

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. Normal creatinine clearance is 88-mL/min for healthy women and 97-137 mL/min for healthy men.

A related kidney test is glomural filtration rate (GFR), which is measured more conveniently by one blood draw. Healthy levels fall somewhere in the neighborhood of 80 to 120.

What constitutes a healthy rate depends on the person's muscle mass, their body size, their activity level, and their medications.

According to the National Kidney Foundation, people in their 20s on the average have a GFR of 116; people 70 and over on the average have a GFR of 75.

Click to to Enlarge This Chart.
Image from a document by Fox & Spach.

Dialysis is usually not required unless the GFR 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
Blood Urea Nitrogen: Biomarker of Health and Longevity
Age-related Risks for Dehydration

National Diabetes Month
Nutrition for Our Age