Creatinine, eGFR and Cystatin C: Why Creatine Can Change a Kidney Blood Test
How creatinine, eGFR, cystatin C and measured GFR tests work, why creatine and meat can shift creatinine, and what to tell the clinician who orders your kidney blood test.
Content last updated . This page has not been medically reviewed.
Urgent first: a flagged result needs a clinician, not a guess
If a kidney test comes back abnormal, the next step is a conversation with the clinician who ordered it. A single high creatinine cannot diagnose a condition, and retesting is usual. [1] Early kidney disease usually has no symptoms, so testing is the only way to know how the kidneys are working. [2] Do not stop a prescribed medicine unless your provider says to. [1]The short answer
Creatine can raise blood creatinine, and creatinine-based estimates can then look worse, even when a directly measured test does not change. [3] Two other approaches, cystatin C and measured GFR, do not rely on muscle creatinine in the same way. [4] Tell the clinician about creatine so the result is read in context.The tests in plain words
| Test | What it is | How creatine or meat may matter |
|---|---|---|
| Blood creatinine | A waste product made when muscle is used and breaks down. [1] | Rises with creatine supplements and meat. [5] Pooled trials found about +0.13 to +0.14 mg/dL. [6] [3] |
| eGFR (estimated) | A calculation that starts from creatinine and adds other details. Creatinine alone cannot determine it. [4] | Can look lower on creatine: one analysis found creatinine-based GFR lower by 10.75 mL/min, another found no significant difference. [3] [6] |
| Cystatin C | A protein made by the body's cells. [7] MedlinePlus says it is not affected by muscle size, age or diet. [4] | Two small trials found no sign of harm (below). It can be inaccurate with untreated thyroid conditions or steroid use. [7] |
| Measured GFR | A marker is injected and the kidneys' clearance is tracked. It is complicated and not widely available. [4] | Used in creatine research (Cr-EDTA); no significant change in the larger analysis. [3] |
| Urine albumin and protein | Larger amounts of albumin in urine may be a sign of kidney damage, and the albumin-to-creatinine ratio uses urine creatinine. [1] | No significant differences in albuminuria, proteinuria or urinary creatinine. [3] |
What creatine studies found with cystatin C
- Healthy men, 3 months: in a randomized trial of 18 men doing aerobic training, cystatin C fell over time, and the authors concluded high-dose creatine did not provoke renal dysfunction. [8] They also suggested the training itself may improve kidney function. [8]
- Parkinson disease, 2 years: in 60 people given creatine or placebo, serum creatinine rose because creatine breaks down to creatinine, while cystatin C and other markers stayed normal. [9]
- Transplant case report: a recipient on a creatine ethyl ester product had a raised creatinine with a normal biopsy; the authors advised measuring filtering another way in such cases. [10]
Proper evidence not found: a large randomized trial using cystatin C as its main kidney outcome in people with kidney disease taking creatine. We searched PubMed for creatine with cystatin C and found only the two small trials above. The studies also used different forms and amounts, and results should not be carried across.
Why meat, muscle and hydration matter
MedlinePlus says high creatinine can come from dehydration, muscle disorders and injuries, intense exercise or a diet high in meat. [1] You may be told not to eat meat for 24 hours before a creatinine test. [1] Muscle mass affects creatinine levels, so a person's muscle can change the number. [4] The National Kidney Foundation says cystatin C may give a more accurate result for older people or those with lots of muscle. [7]Pregnancy and young age also matter: MedlinePlus says cystatin C may be used instead of creatinine for people who are pregnant or under 18. [4] Certain health problems in pregnancy can raise creatinine too. [1] A LactMed entry says creatine can raise an infant's serum creatinine and alter estimates of the infant's kidney function. [11]
What to tell the clinician
- That you use creatine, in what form, and since when.
- Every medicine and supplement you use; MedlinePlus says these can affect test results. [1]
- Whether you are pregnant or breastfeeding.
Proper evidence not found: a published rule for how long creatine should be paused before a kidney test. The clinician decides. Other supplements can affect different lab tests; the Biotin page covers that separate issue.
Related pages
Creatine, kidney questions and creatinine testing gives the overview. Creatine and kidney disease covers who should ask first. See also Standard blood tests and Talking with a health professional.Frequently asked questions
Can creatine make my eGFR look lower?
It can. A 2026 meta-analysis found creatinine-based GFR lower on creatine but not when measured with Cr-EDTA, and another found no significant eGFR difference. [3] [6]
Is cystatin C unaffected by creatine?
MedlinePlus says cystatin C is not affected by muscle size, age or diet, and in two small trials it stayed normal or fell. [4] [8] [9] Untreated thyroid conditions and steroids can make it inaccurate. [7]
Does meat raise creatinine too?
Yes. Meat can temporarily raise creatinine, and some people are asked to avoid it for 24 hours before the test. [1]
Should I tell the lab or my doctor I use creatine?
Tell the person ordering the test. MedlinePlus advises telling your provider everything you take. [1]
What if my creatinine is high?
A single high result cannot diagnose a condition, so expect a retest or other tests. Do not self-treat. [1]
References
- MedlinePlus (US National Library of Medicine). Creatinine Test. Read 2026-10-23.
- National Institute of Diabetes and Digestive and Kidney Diseases (US). Chronic Kidney Disease Tests & Diagnosis. Read 2026-10-23.
- de Souza Almeida A, da Silva LOD, Takahasi BNA, et al. Impact of creatine supplementation on kidney health: a systematic review and meta-analysis. Int Urol Nephrol 2026 (abstract read; authors declare no competing interests). Read 2026-10-23.
- MedlinePlus (US National Library of Medicine). Estimated Glomerular Filtration Rate (eGFR) and GFR Tests. Read 2026-10-23.
- Antonio J, Candow DG, Forbes SC, et al. Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? J Int Soc Sports Nutr 2021 (narrative review, full text read via PMC7871530; several authors declare creatine-industry advisory roles). Read 2026-10-23.
- Tsiaras A, Loufopoulos G, Theodoridis X, et al. The Effect of Creatine Supplementation on Kidney Function: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Ren Nutr 2026 (abstract read). Read 2026-10-23.
- National Kidney Foundation (US). Cystatin C. Read 2026-10-23.
- Gualano B, Ugrinowitsch C, Novaes RB, et al. Effects of creatine supplementation on renal function: a randomized, double-blind, placebo-controlled clinical trial. Eur J Appl Physiol 2008 (abstract read). Read 2026-10-23.
- Bender A, Samtleben W, Elstner M, Klopstock T. Long-term creatine supplementation is safe in aged patients with Parkinson disease. Nutr Res 2008 (abstract read). Read 2026-10-23.
- Law JP, Di Gerlando S, Pankhurst T, Kamesh L. Elevation of serum creatinine in a renal transplant patient following oral creatine supplementation. Clin Kidney J 2018 (case report, abstract read). Read 2026-10-23.
- Drugs and Lactation Database (LactMed), US National Institute of Child Health and Human Development. Creatine. Entry dated 2025 Jul 15 (record read via PubMed). Read 2026-10-23.