Creatine is the supplement most commonly responsible for elevated creatinine on blood tests, but it’s not the only one. High-protein supplements, certain herbal products, and even some compounds that interfere with the lab test itself can all push your creatinine reading higher. The key distinction is whether a supplement is raising creatinine artificially (making the number look worse than your kidneys actually are) or genuinely damaging your kidneys.
Creatine: The Most Common Culprit
Creatine monohydrate, the popular muscle-building supplement, converts directly into creatinine through a spontaneous chemical reaction in your body. This reaction doesn’t require any enzymes. It just happens on its own, driven by body temperature and pH. When you take creatine, your body ends up producing more creatinine as a byproduct, and that shows up on your blood work.
The size of the effect depends on dose and timing. A meta-analysis of creatine supplementation studies found a small but statistically significant increase in serum creatinine, with the effect most pronounced during the first week of use, particularly during “loading phases” where people take around 20 grams per day. After the first week or two, the effect tends to level off as your body adjusts. For reference, normal serum creatinine runs 0.74 to 1.35 mg/dL for adult men and 0.59 to 1.04 mg/dL for adult women. Even a modest bump from creatine supplementation can push someone from “normal” into “flagged” territory on a lab report.
The important point: this is a false elevation. Your kidneys are working fine. The extra creatinine in your blood simply reflects the extra creatine you’re consuming, not declining kidney function. Multiple studies spanning weeks to years have found no serious adverse effects on kidney function from creatine supplementation at standard doses of 5 to 20 grams per day in healthy adults, including older adults and people with type 2 diabetes.
High-Protein Supplements and Diets
Protein powders, amino acid supplements, and high-protein diets raise creatinine through a different mechanism. When your body breaks down protein, creatinine is one of the metabolic byproducts. More protein in means more creatinine out. Data from the OmniHeart Trial showed that people eating 25% of their calories from protein (compared to 15%) had a measurable increase in serum creatinine of about 0.02 mg/dL. That sounds small, but it’s enough to distort kidney function estimates.
The real problem here is what happens to your estimated glomerular filtration rate, or eGFR, the number your doctor uses to assess kidney health. Because eGFR is calculated from creatinine, a protein-driven creatinine increase can make it look like your kidneys are filtering less efficiently when they’re actually filtering more. In the OmniHeart Trial, the high-protein diet actually increased true kidney filtration by about 4 mL/min, but the creatinine-based eGFR equation missed this entirely and showed a slight decrease instead. If you’re taking protein supplements and your doctor flags a low eGFR, this discrepancy is worth knowing about.
Herbal Supplements That Damage Kidneys
Unlike creatine and protein, some supplements raise creatinine the concerning way: by actually injuring your kidneys. More than 100 herbal medicines have been identified as potentially nephrotoxic.
The most notorious is aristolochic acid, found in plants of the Aristolochia genus. First identified as a cause of progressive kidney scarring in Belgian patients in 1993, it can cause irreversible damage to the tissue between your kidney’s filtering units. This condition was originally called “Chinese herb nephropathy” because the plants appeared in some traditional medicine formulations, but the risk exists regardless of how the herb is marketed.
Other herbal products linked to kidney injury include:
- Thunder god vine (Tripterygium), which can cause severe damage to the kidney’s tubular cells
- Rhubarb root (Rheum palmatum), whose anthraquinone compounds, including rhein and emodin, can be toxic to the kidneys under certain conditions
- Mineral-based remedies containing heavy metals like arsenic, mercury, or lead. These metals accumulate in the kidneys because the body can’t clear them efficiently. Traditional preparations such as realgar (containing arsenic) and cinnabar (containing mercury) are known to cause kidney cell death when taken in large quantities
With these supplements, elevated creatinine isn’t a lab artifact. It reflects real kidney damage that may be partially or fully irreversible.
Supplements That Fool the Lab Test
Some substances don’t affect your kidneys at all but interfere with the chemistry of the most common creatinine blood test, called the Jaffé reaction. This test works by reacting a chemical called picric acid with the carbonyl group in creatinine to produce a color change. The problem is that other compounds with similar chemical structures trigger the same reaction, producing a falsely high reading.
Known interferents include high-dose vitamin C (which raises blood glucose and ketone levels), and certain ketone bodies that may be elevated if you’re taking supplements as part of a ketogenic diet. The amino acid precursor 5-aminolevulinic acid (5-ALA), sometimes sold as a supplement, has been specifically identified as causing false creatinine elevations through the Jaffé method. When researchers tested the same blood samples using a different, enzymatic assay, the false elevation disappeared completely.
If your lab uses the Jaffé method (many do, since it’s inexpensive and fast), these interferences are worth keeping in mind. You can ask your doctor whether your creatinine was measured with an enzymatic assay, which is less susceptible to these false positives.
Muscle-Building Supplements and Body Composition
This one is indirect but significant. Any supplement regimen that substantially increases your muscle mass, including creatine, protein, and especially anabolic compounds, will raise your baseline creatinine. Your muscles are the primary source of creatinine in your body, so more muscle means more creatinine production around the clock, independent of what you just ate or took.
Research on bodybuilders illustrates this clearly. In one study, bodybuilders using dietary supplements alone (without anabolic steroids) had creatinine-based eGFR values that looked similar to steroid users, not because their kidneys were equally stressed, but because their high creatine intake and large muscle mass both inflated the creatinine number. The study’s authors noted that using creatinine to estimate kidney function in this population “may create a potential problem” because of how reliably it produces misleading results.
Getting an Accurate Kidney Reading
If you take creatine, protein supplements, or have above-average muscle mass, a creatinine-based kidney function test may underestimate how well your kidneys are actually working. The alternative is a test called cystatin C, a small protein produced by all your cells at a steady rate. Unlike creatinine, cystatin C levels are completely independent of muscle mass, protein intake, and creatine supplementation.
A 2022 expert panel including Veterans Affairs physicians recommended using cystatin C as a confirmatory test whenever creatinine-based eGFR suggests kidney disease but other signs of kidney problems (protein in the urine, structural abnormalities, a history of kidney issues) are absent. If your lab work flags a low eGFR and you’re taking any of the supplements discussed here, requesting a cystatin C test is a straightforward way to find out whether the result is real or an artifact of your supplement routine.