| Marker | Gabriel optimal | Typical lab range | Functional range |
|---|---|---|---|
| Creatinine Men | 0.8 to 1.1 mg/dL | 0.6 to 1.27 | 0.8 to 1.1 |
| Creatinine Women | 0.6 to 0.9 mg/dL | 0.57 to 1 | 0.8 to 1.1 |
What creatinine measures
Your muscles make creatinine at a fairly steady rate as they work. It travels in the blood to the kidneys, which filter it into urine. If the kidneys filter less, creatinine builds up in the blood.
Because the amount you make depends on your muscle mass, what is normal differs by sex, age and body size. That is why labs turn creatinine into an eGFR, which also accounts for age and sex. Gabriel uses separate creatinine ranges for men and women. See the creatinine lab guide.
What a high creatinine can mean
Kidney causes:
- Kidney disease or injury, including infection, poor blood flow to the kidneys or a blockage in the urinary tract.
- Conditions that strain the kidneys, such as diabetes and heart failure.
Causes that raise creatinine without kidney damage:
- High muscle mass. Very muscular people make more creatinine.
- Creatine supplements. Creatine turns into creatinine in the body, so it can raise blood levels and make eGFR look lower.
- A large amount of cooked meat, usually in the day before the test.
- Intense exercise shortly before the draw.
- Dehydration.
- Some medicines, such as trimethoprim, cimetidine, fenofibrate and some HIV medicines.
What a low creatinine can mean
Low creatinine is uncommon and usually not a kidney problem. It often reflects low muscle mass from aging, long illness or a nerve or muscle disorder. It can also come with malnutrition, a vegetarian or vegan diet, pregnancy or severe liver disease.
A low creatinine can make eGFR look higher than your true kidney function, so it is not a sign of extra-healthy kidneys.
What to do with an abnormal result
- Read it with eGFR, BUN and a urine albumin test (UACR). Together they show whether the kidneys are really filtering less.
- Tell your clinician about creatine, protein powders, recent workouts and medicines. Don't stop any prescribed medicine on your own.
- Retest under steady conditions. Drink normally, skip hard exercise and large meat meals for about 24 hours, and pause creatine only if your clinician agrees.
- Ask about cystatin C if you are very muscular, very lean, older, or take creatine. An eGFR using both creatinine and cystatin C is more accurate.
Get prompt care if a high creatinine comes with much less urine than usual, swelling in your legs or face, shortness of breath, confusion, or nausea and vomiting, or if creatinine rises quickly between tests.
Common questions
What is a normal creatinine level?
Ranges vary by lab and sex. Typical lab ranges are about 0.6 to 1.27 mg/dL for men and 0.57 to 1.0 mg/dL for women. Gabriel's optimal range is 0.8 to 1.1 mg/dL for men and 0.6 to 0.9 mg/dL for women.
Does creatine raise creatinine?
Yes. Creatine supplements can raise blood creatinine and make eGFR look lower without kidney damage. Tell your clinician you take it before your labs are read.
Can dehydration raise creatinine?
Yes. Dehydration can raise creatinine for a short time. A recheck when you are drinking normally usually shows your true baseline.
Does working out raise creatinine?
Intense exercise can raise it for a while, and more muscle raises your baseline. Skip hard workouts before a kidney recheck.
Is low creatinine bad?
Usually not on its own. It most often reflects low muscle mass. It can be worth discussing if you are losing weight or muscle without trying.
Sources
- Creatinine Test MedlinePlus, U.S. National Library of Medicine
- Creatinine National Kidney Foundation
- Estimated Glomerular Filtration Rate (eGFR) National Kidney Foundation
- Is It Time for a Requiem for Creatine Supplementation-Induced Kidney Failure? A Narrative Review (Longobardi et al., 2023) Nutrients (via PubMed Central)
This guide is general information, not medical advice. It does not replace a visit with a licensed clinician. Gabriel membership is not health insurance.