Creatine and kidney markers: what elevated creatinine means
The essentials at a glance
Creatine can raise creatinine levels in the blood, and this increase does not automatically mean poorer kidney function. In a review article, Antonio and colleagues state that temporary increases in creatine or creatinine caused by creatine intake probably do not reflect reduced kidney function (2021).
The reason lies in the origin of the value. Creatinine is a breakdown product from muscle, and its amount in the blood depends both on muscle mass and on intake through food and supplements. Thus, the value measures two things at the same time, and the calculation behind it cannot distinguish between them.
You will first read why the level rises in the first place. This is followed by a fact check of three common statements, the evidence on safety, figures on usual intake, a comparison of the three easily confused terms, what to do before a blood draw, the question of which value is better, and the limitations of a measurement.
What to expect in this article
1. Why creatinine levels rise after taking creatine
2. Three statements about creatine and the kidneys in a fact check
3. What the safety assessment actually says
4. Which amounts matter in the assessment
5. Creatine, creatinine, and cystatin C compared
6. What to consider before a blood draw
7. Which value answers the question better
8. Who would benefit from a measurement and who would not
9. What a capillary blood test can show here
10. Limitations: what these values cannot clarify
11. What matters when it comes to creatine and kidney markers
Frequently asked questions
Sources
Why creatinine levels rise after taking creatine
The two words differ by two letters, and that difference determines the answer. Creatine is a substance the body produces itself and that is also found in meat and fish. Creatinine is what remains from it.
The Institute for Quality and Efficiency in Health Care describes creatinine as a breakdown product from muscle that is excreted through the kidneys (as of March 20, 2025). That is precisely why it serves as a kidney marker: what is produced must be removed by the kidneys.
Key message
The creatinine level measures two things at once: how much is supplied and how much the kidneys remove. Creatine intake changes the first factor, and the level rises without the second necessarily having changed.
What actually happens in the muscle
Creatine is found in the muscles, where it serves as a short-term energy store. A small part of this reserve breaks down every day, and creatinine is produced from this breakdown. This is not damage but the normal operation of a storage system.
Because this breakdown occurs at a steady rate, creatinine serves as a measurement marker. The body produces it predictably, and whatever the kidneys do not remove accumulates in the blood. This turns a waste product into a measuring instrument.
The catch lies in the word predictable. The replenishment is predictable only as long as the store does not change. A larger store releases more, and that is precisely the purpose of taking creatine.
The error lies in the calculation, not in the kidneys
Antonio and colleagues describe the problem very directly in their review. Blood creatinine levels can be used as an approximate marker of kidney function, but the amount in the blood is also related to muscle mass and to dietary intake of creatine and creatinine (2021).
The same paper draws a practical conclusion from this. Caution is advised in people who consume large amounts of meat or take creatine supplements when creatinine in the blood and the resulting estimated clearance or filtration rate are used (2021).
Here, caution does not mean alarm but rather proper interpretation. The value is not wrong. It simply answers a different question from the one suggested by the result.
Three statements about creatine and the kidneys: a fact check
The following three statements appear in almost every discussion of the topic. All three sound reasonable, and all three can be evaluated against the evidence.
Checked against the evidence
Common claim
“Creatine damages the kidneys in the long term.”
Substantiated
Antonio and colleagues summarize the experimental and controlled research as showing that creatine intake at recommended amounts causes neither kidney damage nor impaired kidney function in healthy people (2021).
Common claim
“If creatinine rises, the kidneys are filtering less effectively.”
Substantiated
According to the same review, temporary increases in creatine or creatinine in the blood and urine resulting from creatine intake probably do not indicate reduced kidney function (2021).
Common claim
“Then you simply leave out the kidney value when taking creatine.”
Substantiated
The caution concerns creatinine, not the measurement itself (Antonio et al., 2021). For cystatin C, the professional edition of the MSD Manual describes a plasma concentration that is independent of sex, age, and body weight (as of 2025). This points to a different value, not to no value.
The first point needs a qualification so that reassurance does not become a free pass. The cited assessment applies to healthy people and the amounts described in the literature. Anyone with known kidney disease should take this question to a doctor, not a forum.
What the safety assessment actually says
For German-speaking countries, there is a consolidated assessment. In 2020, the Sports Nutrition Working Group of the German Nutrition Society published a position paper on safety aspects of dietary supplements in sports, in which creatine is given its own section.
The paper reproduces the assessment issued by the European Commission’s Scientific Committee on Food in 2000. The following sentence comes from that assessment, and it concerns not the duration of intake but its beginning.
Documented source
“The committee recommended avoiding high initial doses (loading dose).”
Sports Nutrition Working Group of the German Nutrition Society (DGE)
Safety aspects of dietary supplements in sports, Ernährungs Umschau international, 2020
The position paper also states that the committee overall reaffirmed its previous recommendation: avoid high initial doses, and provided a high degree of purity is ensured, health risks are unlikely with an intake of up to 3 grams of creatine per day (2020).
These figures are presented here as a reproduction of an assessment, not as a recommendation. This article does not recommend taking creatine and does not specify a dosage for you to adopt.
Which amounts play a role in the assessment
To put the creatinine level into context, a figure from the same source is helpful: daily turnover. The position paper puts the daily turnover rate of creatine in the body at approximately 2 grams per day (2020).
This figure is the actual benchmark. The body processes creatine every day anyway, and some of it is converted into creatinine, which the kidneys remove. Anyone who additionally takes creatine increases this throughput, and the blood level follows.
Why the turnover rate is the better benchmark
Figures on dietary supplements often seem arbitrary because the reference point is missing. The turnover rate provides that reference point. It indicates how much the body processes each day anyway, thereby turning an amount into a ratio.
The position paper argues along precisely these lines. It contrasts lower intakes similar to the daily turnover rate with high initial doses and reaches a different assessment for the former than for the latter (2020).
This leads to a simple expectation regarding the blood level. The more intake exceeds normal turnover, the more noticeably the creatinine level may change. None of the sources reviewed provides a reliable figure for how much.
Why meat also affects the level
Creatine is found in meat and fish. That is why the review by Antonio and colleagues mentions high meat consumption alongside supplementation when discussing caution regarding creatinine (2021).
For you, this means the effect is not something exotic from strength training. A steak the evening before a blood draw belongs in the same category, just to a lesser extent.
Creatine, creatinine, and cystatin C compared
Three terms that sound similar but mean completely different things on a test report. The table compares them according to the same four criteria.
| Criterion | Creatine | Creatinine | Cystatin C |
|---|---|---|---|
| What it is | A substance produced by the body, also found in meat and fish | A breakdown product of muscle metabolism, excreted through the kidneys | A protein produced by all nucleated cells and filtered by the kidneys |
| Where it appears on the test report | Not measured in a standard laboratory at all; it is not determined routinely | As a standard measure of kidney function, usually together with the estimated filtration rate | As an additional value; according to the MSD Manual, it is not available in every laboratory |
| What muscle mass does to it | More muscle means a larger storage capacity | The blood level is directly related to muscle mass | Plasma concentration independent of sex, age, and body weight |
| What creatine intake changes | Daily turnover rises above the turnover rate of approximately 2 grams | Temporary increase possible, which probably does not reflect reduced kidney function | No effect of creatine intake described in the sources reviewed |
The final line in the right-hand column is deliberately worded cautiously. It does not say that there is no effect, but that the sources reviewed do not describe one. The distinction matters because the absence of a statement is not an all-clear.
What cystatin C measures and where its own limitations lie is covered in the companion article in this cluster: Cystatin C and what the level reveals about your kidney function. This article focuses on what the supplement does to the test result.
What to consider before a blood test
When a value can be influenced by diet, the timing of the measurement also affects the result. This applies twice over to creatinine because two sources come together: your own muscles and what is added from outside.
A higher creatinine level is not the same as poorer kidney function.
A higher creatinine level is not the same as poorer kidney function. Keeping this in mind changes how you read your own test result—and makes it less alarming.
The day before matters more than the time of day
Two things on the previous day affect the creatinine level. One is a large meat meal, because creatine from meat follows the same pathway as creatine from the supplement. The other is a very intense training session.
There is a well-documented parallel for the second point in liver values. The Institute for Quality and Efficiency in Health Care states that, for alanine aminotransferase, strenuous exercise can cause the values to rise temporarily (as of 03/20/2025). At least partly, both values come from the same source—muscles under strain.
So if someone runs a marathon on Sunday and has their levels measured on Monday, the measurement includes the marathon. That does not matter for a snapshot, but it does for a baseline value.
Tell your doctor beforehand
The most important step costs nothing. Anyone taking creatine should mention it before having blood drawn. The review by Antonio and colleagues leads to exactly this conclusion: When using supplements, creatinine and the estimated filtration rate derived from it should be interpreted with caution (2021).
Without this information, a lab report looks like any other. With it, an abnormal value becomes an explainable number, and a further test often becomes a repeat measurement after a few weeks.
Which value answers the question better
The question is not whether to measure, but what to measure. When the confounding factor is known, the solution is obvious: a value that does not depend on that confounding factor.
That is exactly what the MSD Manual, professional edition, describes for cystatin C. The protein is produced by all nucleated cells and filtered by the kidneys, and its plasma concentration is independent of sex, age, and body weight (as of 2025).
The drawback is found in the same source. Tests are not always available, and laboratories do not have standardized values (as of 2025). A cystatin C result is therefore readily comparable within a single laboratory, but less so between two laboratories.
Why both values are nevertheless reported side by side
It would be convenient simply to replace creatinine when taking creatine. Practice argues against this. Creatinine appears on nearly every lab report, providing a long series of comparison values that cystatin C usually does not have.
Then there is the calculation behind it. The MSD Manual points out that creatinine clearance overestimates actual filtration capacity by about 10 to 20 percent in normal kidney function and by up to 50 percent in advanced kidney failure (as of 2025). Knowing about this systematic discrepancy makes it possible to put the value into context rather than replace it.
Not one value instead of the other, then, but the second as a check on the first. If the two differ markedly, that discrepancy itself is the information.
What the urine contributes
Blood values are only half the picture. Protein in the urine is an independent sign of kidney damage, and it does not occur because someone takes creatine or eats a lot of meat.
This is why the Institute for Quality and Efficiency in Health Care describes the early stages of chronic kidney disease using urine tests that detect signs of damage while filtration function is still normal or only mildly impaired (as of August 14, 2024).
Chapter at a glance
Creatinine is the less reliable marker when taking creatine because the intake itself affects it. According to the MSD Manual, Cystatin C does not depend on sex, age, or body weight, but it is not available everywhere and is less comparable across laboratories. A urine test complements both because protein in the urine occurs independently of diet. The most reliable assessment comes from combining these tests and repeating them after a few weeks.
Who benefits from testing and who does not
Not every question requires a blood sample. The following comparison explains both when it applies and when it does not.
Useful for you if …
A previous finding showed an abnormal kidney value and you want to know where you stand now.
You have been taking creatine for some time and have never had a baseline value for comparison.
Kidney disease runs in your family, or you have high blood pressure or elevated blood sugar.
You want to see several values together anyway and the wait for an appointment currently feels too long.
Less suitable if …
You already notice blood in your urine, foamy urine, swollen legs, or a significantly reduced urine volume. This requires immediate medical attention.
You already have known kidney disease. In that case, your treating medical practice will manage the monitoring, and a self-test provides a value without clinical context.
You are hoping the result will authorize you to take a specific amount. No laboratory value can answer that question.
You only tested yesterday. A second result after a few days shows fluctuation, not progression.
What a capillary blood test can show in this situation
A capillary blood self-test measures concentrations at a single point in time. It does not tell you whether your dosage is appropriate, and it is not a diagnostic procedure.
Two tests from mybody®x (MYBODY Lab GmbH) include Cystatin C as a kidney marker, as well as the two liver markers Gamma-GT and GPT. No other test in the range covers all three markers together.
Blood test using capillary blood
Men’s Wellness Check | Men’s Health Test
It includes Cystatin C as a kidney marker, along with Gamma-GT and GPT for the liver and hormone, lipid, and blood glucose values from the same sample. What the test does not do: It does not measure creatinine, so you cannot see how much your creatinine level has shifted due to the intake. It does not measure protein in the urine, does not provide a diagnosis, and does not replace medical evaluation.
Laboratory analysis 3–5 business days after receipt of the sample
Product page information, accessed 12 August 2026
Blood test using capillary blood
Women’s Wellness Check | Women’s health test
It also includes Cystatin C, Gamma-GT, and GPT, along with the complete thyroid profile consisting of TSH, fT3, and fT4. What the test does not do: It also does not include creatinine, and protein in the urine is not measured. It is not a diagnostic procedure and does not replace a medical examination.
Laboratory analysis 3–5 business days after receipt of the sample
Product page information, accessed 12 August 2026
If you want to measure, four things determine how meaningful the result is.
Record your intake
Since when, how much, and in what form. Without this information, an abnormal value cannot be interpreted.
Allow time after training
Do not measure the day after a very strenuous workout or immediately after a large meat-based meal.
Drink enough
Highly concentrated blood raises both kidney values without any change having occurred in the kidneys.
Discuss the result
Abnormal values, together with the intake notes, belong in a doctor’s office, not in a decision you make yourself.
Limitations: what these values do not clarify
None of the sources cited states by how much a creatinine level rises with a specific intake. The review article mentions temporary increases without specifying their magnitude, which is why this article does not include a figure.
The second limitation concerns transferability. The conclusion that intake at the recommended amounts does not cause kidney damage in healthy people applies to healthy people. Nothing can be inferred from it for people with existing kidney disease.
The third limitation is that it is only a snapshot. A single value describes one day. Only two values taken some time apart show a trend, and only a trend is meaningful information.
The fourth limitation lies outside the blood. Protein in the urine is detected using a urine sample, not a blood sample, and an unremarkable blood value does not replace this test.
The objection that four limitations are a lot for a single value is justified. That is true. What matters nevertheless is something else: Once you know which question a value does not answer, you can read the answer to the right question more accurately.
What matters about creatine and kidney values
If you take away just one action from this article, let it be this: Write down on your next lab form or in your phone how long you have been taking creatine and in what amount, and bring this note with you when you have your blood drawn.
The reason is unremarkable. This one line turns an unclear finding into an explainable one, and in the best case it saves you from an examination that only seemed necessary because information was missing.
It all started with the question of whether creatine increases kidney values. The most honest answer is: one of them—and it is the one that already measures two things at once. So the better question is not whether the value rises, but which value was measured.
Frequently asked questions
Does creatine increase kidney values?
It can raise the creatinine level, and this increase does not indicate poorer kidney function. In their review, Antonio and colleagues note that temporary increases in creatine or creatinine in the blood and urine resulting from creatine intake probably do not reflect reduced kidney function (2021). The reason lies in the origin of the value: Creatinine is a breakdown product from muscle and is also affected by dietary intake.
Does creatine harm the kidneys?
Based on the summarized evidence, not in healthy people and at the amounts described. Antonio and colleagues note that experimental and controlled research suggests that creatine intake at the recommended amounts does not cause kidney damage or impaired kidney function in healthy people (2021). The position paper from the DGE’s Sports Nutrition Working Group considers health risks from an intake of up to 3 grams per day unlikely (2020). This explicitly does not apply if kidney disease is already present.
Should I stop taking creatine before a blood test?
This decision belongs in a medical practice, not in an article. What is supported by evidence is the preceding point: Caution is warranted when interpreting blood creatinine and the estimated filtration rate derived from it in people with high meat consumption or those taking creatine supplements (Antonio et al., 2021). Above all, this means reporting creatine use before having blood drawn. Whether stopping it is advisable is a decision for the practice evaluating the results.
Which kidney marker is more informative when taking creatine?
Cystatin C does not have the confounding factor that diminishes the significance of creatinine. The MSD Manual, professional edition, describes its plasma concentration as independent of sex, age, and body weight (as of 2025). However, the same source identifies two limitations: tests are not always available, and laboratories do not have standardized values. A urine test can be added to detect protein in the urine and is independent of diet.
When should I have an abnormal kidney result medically evaluated?
Immediately if there are visible signs, regardless of any supplementation. These include blood in the urine, persistently foamy urine, a marked decrease in urine output, and swollen legs or eyelids. An abnormal laboratory result should also be discussed, because the Institute for Quality and Efficiency in Health Care describes the early stages of chronic kidney disease based on urine and blood tests rather than symptoms (as of August 14, 2024). Anyone who notices warning signs should not take a test but make an appointment.
Next step
First the note, then the result
If you want to establish a baseline after taking creatine, both Wellness Checks measure Cystatin C together with Gamma-GT and GPT. They do not measure creatinine, provide a diagnosis, or replace medical evaluation.
Go to Men’s Wellness Check Go to Women’s Wellness CheckRead more
You might also be interested in this
When it comes to muscles but the results still do not add up.
An overview of which questions a blood test can answer and which it cannot.
Sources
- Antonio J, Candow DG, Forbes SC and others: Common questions and misconceptions about creatine supplementation. Journal of the International Society of Sports Nutrition 18:13, 2021 – link.springer.com
- Ziegenhagen R, Braun H, Carlsohn A et al. (DGE Sports Nutrition Working Group): Safety Aspects of Dietary Supplements in Sports. Ernährungs Umschau international 2/2020 – ernaehrungs-umschau.de
- MSD Manual, Professional Edition: Evaluation of the Patient with Kidney Problems, Maddukuri G, Jaipaul N (2025 edition) – msdmanuals.com
- Institute for Quality and Efficiency in Health Care (IQWiG): Creatinine Clearance, dated 20.03.2025 – gesundheitsinformation.de
The classification of creatinine as an approximation marker, its connection with muscle mass and diet, the statement regarding temporary increases, the cautionary note concerning high meat consumption and supplementation, and the summary on kidney safety in healthy individuals are based on source [1]; they are rendered in substance because the paper was written in English. The verbatim quotation concerning high initial doses, the turnover rate of approximately 2 grams per day, and the classification of an intake of up to 3 grams per day are taken from [2]. The information on cystatin C, its production in all nucleated cells, the independence of its plasma concentration, and the lack of standardization are taken from [3]. The description of creatinine as a breakdown product of muscle is taken from [4]. The classification of the early stages of chronic kidney disease is based on the IQWiG text “How does chronic kidney disease (renal insufficiency) progress?”, dated 14.08.2024; the note on temporarily elevated values after strenuous exercise is based on the IQWiG text “Alanine aminotransferase (ALAT),” dated 20.03.2025; both are attributed in the text to the institution and date. Information on prices, values, sample type, and laboratory is taken from the mybody®x product pages, accessed on 12.08.2026; processing times follow the central specification for blood tests. All sources were accessed and reviewed on 12.08.2026.
mybody®x Editorial & Expert Team
Laboratory diagnostics Nutritional science Blood analysis interpretation Nutrigenetics
This article was created by the mybody®x editorial and expert team. The team combines laboratory diagnostics, nutritional science, and the interpretation of blood analyses. Contributors are listed on the authors page.
Published on 12.08.2026 · Last updated on 12.08.2026
The content is intended for general information and does not replace medical advice, diagnosis, or treatment. Reference ranges depend on the laboratory, method, and age; the information on your test report is always authoritative.
Share now:
Pharmacies offer self-tests, not DNA analyses.
Cortisol and weight gain: what is actually proven