Explainer · updated 2026-09-09
Creatinine, explained in plain English
Key facts
- Typical adult reference interval in women: 0.5-1.1 mg/dL (ABIM)
- Typical adult reference interval in men: 0.7-1.3 mg/dL (ABIM)
- The same intervals in umol/L (converted from the ABIM ranges): 44.2-97.2 in women, 61.9-114.9 in men umol/L (ABIM)
- What creatinine is: a waste product from muscle that the kidneys clear steadily; the estimate beside it is worked out from this figure and your age (NICE 2021)
- What even a small rise stands for: a large fall in filtration, so a reversible cause is sought (NICE 2021)
What it is
Creatinine is a waste product from muscle that the kidneys clear steadily. It is measured because it is easy, and because the estimated filtration rate printed beside it is worked out from this figure and your age. The result on your report is the creatinine in your blood.
What the number is telling you
Creatinine tells your doctor how steadily the kidneys are clearing this waste. It is a snapshot, and it means something only next to your age, how much muscle you carry and your previous results. One reading says little; time and trend matter.
What high or low can mean
High: Filtering has slowed. Even small rises stand for large falls in filtration, so a reversible cause is sought. Where your own level sits, and what is behind it, is for your doctor to say.
Low: A low figure usually reflects little muscle rather than good kidneys, which is why the estimate can mislead. Muscle is where creatinine comes from, so how much you carry moves this number without the kidneys changing: with heavy muscle the estimated filtration rate reads low, and with wasted muscle it reads high.
What a typical result looks like
Typical adult reference intervals from ABIM run from 0.5 to 1.1 mg/dL in women and 0.7 to 1.3 mg/dL in men, about 44.2 to 97.2 and 61.9 to 114.9 umol/L. The range on your own report is the one that counts.
Questions worth asking your doctor
- How much muscle I carry affects this number; how is my result being read with that in mind?
- What does the estimated filtration rate beside it add to the picture?
- If my level is high, what reversible causes are you checking for?
- How does this compare with my previous results?
If a result worries you, ask your doctor.
Sources
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