Supplements That Can Skew Your Bloodwork

2 min read

8/13/26

Key Takeaways

High-dose biotin in certain hair, skin, and nail products can interfere with certain immunoassays, producing falsely high or low results.
Creatine raises creatinine and can make eGFR look lower with zero change in kidney function.
Topical hormones can contaminate the sample itself: wash the site, and keep creams off the collection arm for 24 hours.

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Therapy & Supplements

Supplements That Can Skew Your Bloodwork

2 min read

8/13/26

Key Takeaways

High-dose biotin in certain hair, skin, and nail products can interfere with certain immunoassays, producing falsely high or low results.
Creatine raises creatinine and can make eGFR look lower with zero change in kidney function.
Topical hormones can contaminate the sample itself: wash the site, and keep creams off the collection arm for 24 hours.

Biotin

Hair-skin-nails products can contain biotin at doses far above ordinary nutritional intake, and high doses can interfere with certain laboratory immunoassays making some hormone, thyroid, or vitamin results appear falsely high or falsely low. That's analytical interference, not real biology. Include biotin whenever you report your supplement use, so results can be interpreted correctly.

Creatine

Creatinine is a byproduct of muscle metabolism, so creatine supplementation, higher muscle mass, recent training, and meat intake all raise it and can make calculated eGFR appear lower without any real decline in kidney filtration. The trend under consistent conditions, read against your broader metabolic picture, is what matters.

Topical Hormones

Testosterone or estrogen cream on or near the collection site can enter the sample directly and produce an artificially high result and transfer happens via hands, towels, clothing, bedding, or a partner. Before testing: scrub the site with soap and water, dry with a clean paper towel, and avoid applying topical hormones to the collection arm for at least 24 hours.

None of this means stop your supplements. It means tell your data the truth: use consistently, disclose what you take, and test under similar conditions.

Frequently Asked Questions

How is Rythm different?

Most blood testing companies charge $500 or more for a single test per biomarker, providing only a one-time snapshot that doesn’t capture your long-term health trends or reflect your true baseline. This approach can lead to missed patterns or even misdiagnoses due to limited data. Rythm takes a different approach, using monthly tracking to build a detailed picture of your health over time. This allows for more accurate insights, better optimization, and a clearer understanding of how your body is evolving.

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Rythm provides actionable suggestions and tips to help you optimize each biomarker

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Yes, Rythm is HIPAA compliant. Your data is securely stored and handled in accordance with strict privacy and security standards.

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Yes, Rythm is HSA/FSA eligible. You can use your HSA or FSA card at checkout or submit your Rythm receipt to your provider for reimbursement.

How long does it take to get my results?

You will receive your results within 3 business days – as long as it's returned within 7 days of receiving your kit. Delays can occur if you do not send your sample back in time.