eGFR creatine interference: How creatine affects kidney function tests

When you take creatine, a popular supplement used to boost muscle strength and recovery. Also known as creatine monohydrate, it helps your muscles produce energy faster. But here’s the catch: it also raises your blood creatinine, a waste product your kidneys filter out levels — and that can mess with your eGFR, the standard test doctors use to estimate how well your kidneys are filtering blood.

Most people don’t realize that a high creatinine number doesn’t always mean your kidneys are failing. If you’re taking creatine, your body is just making more of it — not because your kidneys are struggling, but because you’re feeding them extra raw material. That fake spike can make your eGFR look worse than it is. Some people even get flagged for "reduced kidney function" when their kidneys are perfectly healthy. This isn’t rare. Studies show up to 30% of athletes and fitness-focused users see this effect. And if you’re on medication for high blood pressure or diabetes, your doctor might misread the results and change your treatment plan unnecessarily.

That’s why knowing about eGFR creatine interference matters. If you’re supplementing with creatine and need a kidney test, the smart move is to stop for 3–5 days before your blood draw. It gives your body time to clear the extra creatinine. Tell your doctor you’re taking it — don’t wait for them to guess. Many don’t ask. But if you speak up, you avoid false alarms, unnecessary follow-ups, or even stress over a fake diagnosis. This isn’t about quitting creatine. It’s about making sure your test results reflect your real health — not your supplement routine.

Below, you’ll find real-world posts that dig into how medications, supplements, and lab tests interact — from how antibiotics affect side effect timing to how garlic extract can change your blood markers. Each one helps you spot hidden patterns in your own health data. You’ll learn what to ask, what to track, and when to push back when something doesn’t add up.