What your creatinine and eGFR mean

Lab marker guide · Updated June 2026

Understanding lab results

What they measure

Creatinine is a waste product your muscles produce at a fairly steady rate. Healthy kidneys filter it out, so the amount left in your blood is a window into how well they're filtering.

eGFR (estimated glomerular filtration rate) takes your creatinine, age, and sex and estimates your overall kidney filtration — reported as a number where higher is better. It's the headline kidney-function figure most clinicians use.

The two move in opposite directions: higher creatinine → lower eGFR.

Typical ranges

• Creatinine: ~0.7–1.3 mg/dL (men), ~0.6–1.1 mg/dL (women) — it scales with muscle mass, so muscular people naturally run higher.
• eGFR: above 90 is typically normal; 60–89 is mildly reduced (often fine, especially with age); below 60 sustained for 3+ months can indicate chronic kidney disease.

Units and equations vary by lab and country — read against your report.

What high creatinine / low eGFR can mean

A genuinely reduced eGFR suggests the kidneys are filtering less efficiently, which warrants follow-up. But creatinine is easily nudged by everyday factors:

• Dehydration (very common)
• Intense exercise or a recent workout
• A high-protein meal or creatine supplements
• High muscle mass (a natural, benign reason)

So one elevated reading isn't automatically a kidney problem — context and a recheck matter.

Why the trend matters

Kidney function changes slowly, and single creatinine readings bounce around with hydration and activity. The trend across several tests is what reveals a real, gradual change versus a one-off blip from a gym session or a dry day. Seeing eGFR plotted over time — alongside blood pressure, glucose, and hydration habits — is exactly the connected view scattered PDFs can't give. See how to read your blood test results and tracking lab results over time.

When to talk to a doctor

A low eGFR (especially below 60), a rising creatinine trend, or kidney markers flagged alongside high blood pressure or glucose should be reviewed by a clinician. For more on understanding your panels, browse the rest of the Quanome blog.

Frequently asked questions

What do creatinine and eGFR measure?

Creatinine is a waste product from normal muscle activity that your kidneys filter out, so blood creatinine reflects how well they're filtering. eGFR (estimated glomerular filtration rate) is a calculation based on creatinine, age, and sex that estimates your overall kidney function as a percentage-like number.

What is a normal creatinine and eGFR?

Creatinine commonly runs ~0.7–1.3 mg/dL for men and ~0.6–1.1 mg/dL for women (it scales with muscle mass). For eGFR, above 90 is typically normal, 60–89 mildly reduced, and below 60 sustained for 3+ months can indicate chronic kidney disease.

What does high creatinine mean?

Higher creatinine (and lower eGFR) suggests the kidneys are filtering less efficiently. But it can also rise temporarily from dehydration, intense exercise, a high-protein meal, high muscle mass, or certain supplements (like creatine), so context matters.

Can a single high creatinine be a false alarm?

Yes. Dehydration, a recent workout, or creatine supplements can transiently raise it. That's why a single value is often rechecked, and why the trend over time is more meaningful than one reading.