Creatinine and eGFR — Kidney Function
Serum creatinine and the calculated eGFR estimate the kidney filtration rate. Heavily muscled adults run higher creatinine without true kidney impairment.
Serum creatinine and the calculated eGFR estimate the rate at which your kidneys filter blood, the core measure of kidney function. Heavily muscled adults run higher creatinine without true kidney impairment — interpret with body composition in mind.
The biomarker
- Name: Creatinine + eGFR
- Units: Creatinine mg/dL; eGFR mL/min/1.73m²
- Standard reference range: Creatinine 0.6–1.3; eGFR > 60 considered normal
- Optimal range: Creatinine 0.7–1.1 (men); 0.6–0.9 (women); eGFR > 90
How to read your result
| Value | Interpretation |
|---|---|
| eGFR > 90 | Normal |
| 60–89 | Mildly reduced — recheck and pair with urine ACR |
| 30–59 | Moderate CKD — see clinician |
| < 30 | Severe — urgent referral |
What moves the needle
- Diet. Moderate protein, low salt.
- Testing. Add urine albumin-creatinine ratio (ACR) for kidney health.
- Hydration. ≥ 2 L water daily.
- Medication. Review NSAIDs with clinician.
Why this test is worth asking for
- eGFR estimates kidney filtration rate from a single blood draw, giving an early read on declining function before symptoms appear.
- Body composition matters: heavily muscled adults can run higher creatinine without true impairment, so the number must be read in context.
- Pairing it with a urine albumin-creatinine ratio catches kidney stress that filtration rate alone can miss.
Related protocols
- HbA1c — Three-Month Glucose Average
- Fasting Glucose — Baseline Metabolic Marker
- Vitamin D — 25-Hydroxyvitamin D
Sources
AgeGen lab guides are educational only. We do not provide medical diagnosis, prescribe brands, or recommend specific doses. Talk to a licensed clinician before changing your supplement or medication routine.