Creatinine, the kidney filter check Serum Creatinine
A waste product your muscles make all day, which your kidneys clear out.
Also printed asCreatinine · Creat · S.Creatinine
What it measures
A waste product your muscles make at a steady rate and your kidneys clear steadily.
The number every kidney estimate is built from - but it also rises with muscle mass, meat intake and dehydration.
Why it matters for how long you stay well
Kidneys lose filtering quietly over decades and rarely announce it, so a number that creeps up across reports is worth catching while there is still plenty of room to act.
How it shows up in daily life
A heavy gym week, a lot of meat, or a hot day with too little water will nudge this up without anything being wrong.
High and low readings
When it reads high
Kidneys may be filtering less, or you were dehydrated, very muscular, or had a protein-heavy day.
When it reads low
Low muscle mass; rarely a problem.
What moves it
Daily life
- how much muscle you carry
- meat and protein powder in the days before the test
- how much water you drink
- hard exercise before the draw
Medicines known to shift it
- NSAIDs (can raise it)
- blood-pressure medicines (can raise it)
- diuretics (can raise it)
Listed so a result can be read in context. It is not advice to start, stop or change any medicine; that decision belongs with your physician.
Read it with
Markers that move this one, or that this one moves. One number read alone can mislead.
- eGFR, your kidney filtering rateKnown mechanism
As this rises, eGFR is calculated from it
Your filtering rate was never measured. It is your creatinine put through a formula with your age and sex, which is why muscle changes it on paper.
- Urea–creatinine balanceKnown mechanism
As this rises, Urea–creatinine balance falls as it rises
Creatinine sits at the bottom of that fraction. So a large muscle mass, which raises creatinine, narrows the balance without anything happening to your kidneys.
Common questions
What does Serum Creatinine measure?
A waste product your muscles make at a steady rate and your kidneys clear steadily. The number every kidney estimate is built from - but it also rises with muscle mass, meat intake and dehydration.
What does a high Creatinine result usually mean?
Kidneys may be filtering less, or you were dehydrated, very muscular, or had a protein-heavy day.
What does a low Creatinine result usually mean?
Low muscle mass; rarely a problem.
What is the usual reference range for Creatinine?
A broad adult reference band is 0.7–1.3 mg/dL. For women the band is 0.6–1.1 mg/dL. Labs differ, so read your result against the band printed on your own report.
Educational only, not a diagnosis. A single number means little without your history and the rest of your panel, so discuss your own results with your physician.
Typical adult reference band
- Men
- 0.7–1.3 mg/dL
- Women
- 0.6–1.1 mg/dL
Labs differ. The band printed on your own report is the one that applies to your result.
Reported in mg/dL
Ageing relevance
5/5
A direct input to a validated biological-age algorithm.
One of the nine blood inputs to the PhenoAge biological-age clock (Levine et al., Aging, 2018).
Worth knowing
It comes from muscle, so a heavily built person runs a higher level with perfectly healthy kidneys.
Have a report with this marker on it? Read it in context.
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