My Creatinine Is High- Does That Mean I Have Kidney Disease?

By Dr. Sruti Chintamaneni, MD (Internal Medicine & Primary Care, Nephrology & Hypertension, USA)
Consultant Physician and Panel Member of Medicine and Science, 150.fit

Seeing an “abnormal” lab result can be stressful, especially when it involves your kidneys.  One of the most common questions patients ask is: “My creatinine is high. Does this mean I have kidney disease?”

The answer is: Not necessarily.

While creatinine is an important indication of kidney function, it’s only one piece of the puzzle. In many healthy people, the creatinine can be slightly elevated - even when the kidneys are working perfectly well. So let’s break it down.

First of all, what is creatinine?

Creatinine is a waste product that your body makes every day. It comes from your muscles as they use energy to move, exercise, and carry out normal daily activities. The kidneys act like filters. They remove creatinine from your blood and send it out of your body through urine.So doctors can use the blood creatinine level to estimate how well your kidneys are filtering your blood. But here’s the important part:Creatinine is an estimate of kidney function—it isn’t a direct measure of kidney health. That means other factors can affect your creatinine level, even if your kidneys are completely healthy.

Why might creatinine be high IF my kidneys are NORMAL?

The most simple reason might be that you may just have more muscle. And, muscle naturally produces creatinine.

If you’re someone who: Lifts weights, Exercises regularly, Has a naturally muscular build your creatinine may run a little higher than average simply because you have more muscle - not because your kidneys are damaged.

You take creatine supplements

Creatine is one of the most popular supplements for improving strength and exercise performance. Your body converts a small amount of creatine into creatinine, so taking a creatine supplement can make your blood creatinine level go up! So…does that mean creatine is harming your kidneys?

For most healthy adults, no. Research has consistently shown that recommended doses of creatine do not damage healthy kidneys. It simply makes creatinine a less reliable test because there’s more of it being produced.

* If you already have kidney disease, talk to your healthcare provider before taking creatine You eat a high-protein diet*

"Many people worry that protein shakes or a high-protein diet will “hurt the kidneys.” For people with healthy kidneys, there is no good evidence that a reasonable high-protein diet causes kidney disease. Protein powder itself usually doesn’t raise creatinine very much. But, those who eat lots of protein are often more physically active and have greater muscle mass, which can contribute to slightly higher creatinine levels.

*If you already have chronic kidney disease, your doctor may recommend limiting protein based on your specific condition*

You exercised hard before your blood test A tough workout the day before your labs can temporarily increase creatinine because your muscles are working harder and producing more of it.

You were dehydratedNot drinking enough fluids can temporarily make creatinine appear higher than usual. Once you’re well hydrated, the level often returns to normal.

Some medications can affect the test Certain medications can raise creatinine without actually harming the kidneys.That’s why it’s important to let your healthcare provider know about all prescription medications, over-the-counter medicines, and supplements you’re taking!

If creatinine isn’t perfect, is there a better test?

Another blood test called cystatin C can give doctors a clearer picture of kidney function. Unlike creatinine, cystatin C is: Much less affected by muscle mass, Not affected by creatine supplements, Less influenced by diet or exercise This makes it especially helpful if you’re very muscular, take creatine, or have a creatinine result that doesn’t seem to fit the rest of your health. Sometimes your doctor will order both creatinine and cystatin C to get the most accurate estimate of kidney function.

Should I stop taking creatine or protein powder? Not necessarily.

If your kidneys are healthy, there’s no reason to panic because your creatinine increased after starting creatine or protein powder. Often, the higher number reflects how the test works—not kidney damage.Before stopping any supplement, talk with your healthcare provider. They can determine whether your creatinine reflects true kidney disease or simply your body composition, diet, or exercise routine.

A high creatinine level does not automatically mean you have kidney disease.

Many healthy people have higher creatinine levels because of:

More muscle

Creatine supplements

Regular exercise

Mild dehydration

Certain medications

When the answer isn’t clear, a cystatin C blood test can often provide a more accurate picture of how well your kidneys are working. The most important thing to remember: Don’t focus on one lab number in isolation. Your healthcare provider will look at your symptoms, family and medical history, urine tests, blood pressure, and sometimes cystatin C to determine whether your kidneys are truly healthy.

• KDIGO (2024). Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease.
  Useful for the article’s overall explanation of creatinine, eGFR, cystatin C, CKD diagnosis, and factors that can make creatinine less reliable. KDIGO specifically notes that high muscle mass, intense exercise/bodybuilding, high-protein diets, creatine supplements, and some medications can affect serum creatinine independently of true GFR.
  KDIGO 2024 CKD Guideline
• National Kidney Foundation. Estimated Glomerular Filtration Rate (eGFR).
  Supports the explanation that creatinine is influenced by factors other than kidney function, including muscle size and diet, and that creatinine is used to estimate rather than directly measure GFR.
  National Kidney Foundation: eGFR
• National Kidney Foundation. Cystatin C.
  Supports the section explaining why cystatin C can be useful when creatinine may be less reliable, including situations involving unusual muscle mass. Combining creatinine and cystatin C can also improve the accuracy of estimated GFR in appropriate circumstances.
  National Kidney Foundation: Cystatin C
• Tsiaras A, et al. The effect of creatine supplementation on kidney function: a systematic review and meta-analysis of randomized controlled trials. Journal of Renal Nutrition. 2026.
  This is a particularly useful reference for your creatine supplementation section. The meta-analysis found a small increase in serum creatinine with creatine supplementation, without a significant difference in urea or eGFR, supporting the point that elevated creatinine after supplementation does not necessarily indicate kidney injury.
• Impact of creatine supplementation on kidney health: a systematic review and meta-analysis. 2026.
  Another recent meta-analysis found that creatine supplementation increased serum creatinine and altered creatinine-based estimates of GFR, while measured GFR and markers such as albuminuria/proteinuria did not show corresponding deterioration.