Is creatine bad for kidneys? In healthy people taking recommended doses, controlled research has not shown kidney damage, according to the International Society of Sports Nutrition. Creatine can still raise blood creatinine, the waste product used to estimate kidney function, so a routine blood test may suggest lower kidney function than you really have.
That gap between the number and the kidney is easy to misread. This guide explains the creatine and creatinine link, what international, UK, US and Australian guidance says, when cystatin C helps and what to tell the clinician who orders your tests. People with known kidney disease need individual advice.
Is creatine bad for kidneys in healthy men?
Creatine has not been shown to harm the kidneys of healthy people at recommended doses. The International Society of Sports Nutrition (ISSN) position stand reports that researchers have found no compelling evidence that creatine supplementation negatively affects kidney function in healthy or clinical populations. A later ISSN review of common questions reached the same conclusion for healthy individuals.
Some of the stronger evidence uses measured rather than estimated kidney function. A 2023 narrative review describes its authors' trials, some using 51Cr-EDTA clearance, a gold-standard filtration test. They found no harmful effect of creatine monohydrate on kidney function in groups that included resistance-trained men eating 1.2 to 3.1 g of protein per kg of body weight a day.
The evidence is not a blanket guarantee. The KDIGO 2024 kidney guideline notes that creatine supplements used for bodybuilding have been associated with allergic interstitial nephritis, an inflammatory reaction in kidney tissue. The 2023 review says more studies are needed in people with pre-existing kidney disease. For the basics of the supplement itself, see creatine monohydrate for men.
Creatine vs creatinine: what is the difference?
Creatine is a compound stored mainly in muscle, made by the body and also eaten in meat or taken as a supplement. Creatinine is its breakdown product. The ISSN review explains that creatine and phosphocreatine in muscle break down without enzymes into creatinine, which passes into the blood and is filtered by the kidneys.
The 2023 review puts that conversion at about 2% of the body's total creatine pool per day. Taking creatine enlarges the pool, so in some people more creatinine reaches the blood.
Laboratories use blood creatinine to calculate eGFR, the estimated glomerular filtration rate. eGFR estimates the amount of fluid the kidneys filter each minute, adjusted to a standard body size and reported in mL/min/1.73 m². When creatinine rises for reasons unrelated to the kidneys, eGFR falls even if filtration has not changed.
Does creatine increase creatinine levels?
Creatine can increase blood creatinine, but not in everyone. The ISSN review cites an earlier analysis of creatine studies: 12 showed no rise in serum creatinine, 8 showed a rise that stayed within the normal range, and 2 showed a rise above normal limits.
Muscle mass and diet move creatinine too. NICE says creatinine-based eGFR may be less reliable in adults with higher muscle mass or who use protein supplements, and that increased muscle mass leads to underestimation of kidney function.
Meat matters on the day. KDIGO describes a study in which a cooked meat or fish meal raised serum creatinine by about 0.23 mg/dL, equivalent to an eGFR drop of about 20 mL/min/1.73 m² in that population. The ISSN review estimates that meat contains about 0.7 g of creatine per 6 oz serving.
What kidney test guidance says about lifters
Kidney test guidance in each region aims at a reliable creatinine result, but the details differ, especially on meat before the test.
| Region | Source | What it says |
|---|---|---|
| International | KDIGO 2024 | Creatine supplements, high-protein diets and bodybuilding can distort creatinine; use creatinine plus cystatin C when it matters for decisions |
| UK | NICE NG203 | Interpret creatinine eGFR with caution in bodybuilders; no meat for 12 hours before testing |
| US | NIDDK | Creatinine plus cystatin C is preferred and more accurate than creatinine alone |
| Australia | Healthdirect | Avoid cooked meat for 4 to 6 hours before an eGFR test |
KDIGO adds that waiting at least 12 hours after meat or fish best avoids the meal effect, while acknowledging this can be hard to arrange. Healthdirect gives the shorter Australian window. Follow the instructions on your own request form, and see fasting before a blood test for the wider rules.
Units also differ between reports. The US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) gives reporting rules for creatinine in both mg/dL and µmol/L, so check which unit your result uses before comparing it with anything online.
When does a cystatin C test help?
Cystatin C is a protein made by the body and filtered by the kidneys, which KDIGO describes as an alternative filtration marker. KDIGO notes that creatinine is directly linked to muscle mass while cystatin C is affected by different factors, so cystatin C can check a creatinine result that muscle or supplements may have skewed.
KDIGO recommends using an eGFR calculated from both creatinine and cystatin C when creatinine-based eGFR is less accurate and kidney function affects clinical decisions. For bodybuilders, KDIGO says a cystatin C eGFR may be appropriate if increased muscle mass is the only abnormality.
UK guidance differs. NICE NG203 removed its earlier recommendations to use cystatin C in diagnosing chronic kidney disease because the evidence on diagnostic accuracy was insufficient. Ask your clinician which assessment fits your circumstances and local pathway.
Cystatin C has its own blind spots. KDIGO lists steroid use, thyroid disease and cancer as influences on cystatin C. NIDDK also notes that cystatin C is not yet routinely measured in clinical practice, so you may need to ask for it.
Should you stop creatine before a blood test?
None of the guidance cited here sets a standard creatine-free period before a kidney blood test. The most useful step is to tell the person ordering the test that you take creatine, train hard and eat a high-protein diet, so the result is read in context.
If an eGFR comes back low, NICE advises confirming an eGFR below 60 in an adult not previously tested by repeating the test within two weeks. KDIGO advises clinicians assessing a change in eGFR over time to consider a recent meat meal, a change in muscle mass or extreme activity. Whether to pause creatine before a repeat test is a decision to make with your clinician. For your daily intake, see protein intake for men who lift.
Practical checks before a kidney blood test
1. List creatine on your medication and supplement form.
Include the product, the daily amount on the label and how long you have taken it. A clinician cannot adjust for a supplement nobody mentioned.
2. Read the preparation instructions for meat.
NICE says no meat for 12 hours; healthdirect says avoid cooked meat for 4 to 6 hours. Follow your own laboratory's instructions and note what you ate.
3. Record recent hard training.
KDIGO names extreme activity and changes in muscle mass among factors to consider. Write down heavy sessions in the days before the draw.
4. Check the unit and the equation on the report.
Note whether creatinine is in mg/dL or µmol/L and which eGFR equation the laboratory used. NIDDK advises comparing eGFR values calculated with the same equation.
5. Ask about cystatin C before accepting a label.
If a borderline eGFR would lead to a diagnosis or a change in medicines, ask whether a cystatin C test would make the estimate more accurate.
When to see a doctor about kidney results
The NHS lists symptoms of acute kidney injury: peeing a lot less than usual, feeling very thirsty, nausea or vomiting, swollen feet or legs, feeling tired, dizzy, confused or sleepy, and breathlessness, especially when lying down. The NHS advises an urgent GP appointment or NHS 111 if you think you have these symptoms. If someone is seriously ill, call 911 in the US, 999 in the UK or 000 in Australia.
The NHS also lists dehydration and long-term use of some medicines, including anti-inflammatory painkillers, among possible causes. If you have a known kidney condition, discuss creatine with your doctor before starting; the ISSN position stand notes that some experts advise this.
At the appointment, ask whether creatine, muscle mass or diet could explain the result, whether to repeat it and whether cystatin C would help. Start with your US primary care physician, UK GP or Australian GP. If you are planning broader testing, see annual blood work for men.
Frequently asked questions
Does creatine increase creatinine?
Creatine can increase blood creatinine because creatine breaks down into creatinine at about 2% of the body's pool per day. In one analysis of studies, most showed no rise or a rise within the normal range, and only 2 showed a rise above normal limits. A higher creatinine does not by itself mean kidney damage.
Can creatine cause a falsely low eGFR?
Yes. eGFR is calculated from creatinine, so anything that raises creatinine without affecting the kidneys, such as creatine supplements, high muscle mass or a recent meat meal, can make eGFR look lower than true kidney function. NICE advises caution interpreting creatinine-based eGFR in bodybuilders and people using protein supplements.
Should I stop creatine before a blood test?
The guidance reviewed here sets no standard creatine-free period before a kidney test. Tell the clinician ordering the test that you take creatine, train hard and eat a high-protein diet. If a result is borderline, ask whether to repeat it, whether to pause creatine first and whether to add cystatin C.
Is creatine safe if I have kidney disease?
People with kidney disease need individual advice. The ISSN position stand found no compelling evidence of harm, but notes some experts advise people with pre-existing kidney disease to consult a physician first. A 2023 review says more studies are needed in this group, so discuss it with your kidney doctor.
What is cystatin C?
Cystatin C is a protein made by the body and filtered by the kidneys. Creatinine is directly linked to muscle mass, while cystatin C is affected by different factors, so it can check a creatinine result skewed by muscle or creatine. KDIGO recommends combining creatinine and cystatin C when creatinine-based eGFR is less accurate and the result matters.
The short version
Creatine has not been shown to damage healthy kidneys at recommended doses, but it can raise creatinine and lower a creatinine-based eGFR. Muscle mass, high-protein diets and meat before the test do the same. Tell your clinician about creatine and training, follow your lab's preparation instructions and ask about cystatin C if a borderline result would change decisions. People with kidney disease need individual advice.
This article is general education, not medical advice. It does not replace your own physician.
