Biomarker · Kidney
Creatinine
Creatinine is a waste product filtered by the kidneys and the basis of eGFR. Learn what a creatinine test shows and why muscle mass affects it.
Written by LON6EVITY Editorial Team · Last updated
Overview
Creatinine is produced by normal muscle metabolism and removed from the blood by the kidneys. Blood creatinine rises when kidney filtration falls.
Why it matters
Creatinine is used to estimate kidney function (eGFR) and to monitor people with conditions such as diabetes or high blood pressure that can affect the kidneys.
Factors affecting the result
Muscle mass has a large effect: muscular people can have higher creatinine with normal kidneys, and people with low muscle mass can have low creatinine. Intense exercise, dehydration, high meat intake and certain medications also influence results.
How the test is performed
A blood sample, often part of a metabolic panel.
Reference ranges
Reference ranges and targets differ between laboratories, units and guidelines, and depend on age, sex, method and your overall clinical picture. A single result is not a diagnosis — interpret it with a qualified clinician.
Factors that can affect the result
- Muscle mass
- Hydration
- Recent intense exercise
- Cooked meat intake
- Medications
Questions people commonly ask
- Why is creatinine converted to eGFR?
- eGFR adjusts creatinine for age and sex to better estimate how well the kidneys filter.
Related biomarkers
Related tests
Related topics
Understand your biomarkers in context
What does this mean for your own health data? Log your results, follow trends over time and bring an organised summary to your next doctor's appointment.
Sources
- Creatinine Test. MedlinePlus, U.S. National Library of Medicine.
- Estimated Glomerular Filtration Rate (eGFR). National Kidney Foundation.