Creatinine & eGFR (Kidney Function)
Creatinine is a waste product produced by muscle metabolism. Healthy kidneys continuously filter creatinine from the blood into urine. When kidneys are damaged, creatinine builds up in the blood. The estimated Glomerular Filtration Rate (eGFR) is calculated from creatinine, age, sex, and race to estimate how well the kidneys are filtering — it is the primary measure for staging chronic kidney disease (CKD).
Normal Range
Creatinine: Men 0.7–1.2 mg/dL; Women 0.5–1.0 mg/dL | eGFR ≥ 90 is normal; 60–89 mildly reduced
Reference ranges may vary slightly between laboratories. Always interpret your result in context with your doctor.
Why is Creatinine / eGFR measured?
Creatinine and eGFR are ordered to evaluate kidney function, monitor people with diabetes, hypertension, or known kidney disease, assess medication safety (many drugs require dose adjustment in kidney impairment), and investigate unexplained swelling, fatigue, or changes in urination.
High Creatinine / eGFR means…
High creatinine and low eGFR indicate the kidneys are not filtering adequately. Causes range from acute dehydration (easily reversible) to chronic kidney disease (CKD). An eGFR persistently below 60 for more than 3 months confirms CKD and requires nephrology evaluation.
Low Creatinine / eGFR means…
Low creatinine is less clinically significant and usually reflects low muscle mass (elderly patients, malnutrition, or muscle-wasting conditions). Pregnancy also causes physiologically low creatinine due to increased kidney filtration.
Symptoms associated with abnormal Creatinine / eGFR
When Creatinine / eGFR is high:
- Swelling in ankles, feet, or hands (oedema)
- Fatigue and difficulty concentrating
- Decreased urine output or dark urine
- Nausea and loss of appetite
- Itching (uraemia in advanced disease)
- Shortness of breath
When Creatinine / eGFR is low:
- Usually no symptoms (incidental finding)
- Associated with muscle wasting conditions
How to improve your Creatinine / eGFR
- Stay well-hydrated — even mild chronic dehydration stresses kidneys.
- Control blood pressure and blood sugar rigorously if you have diabetes or hypertension — these are the two leading causes of kidney disease.
- Avoid long-term use of NSAIDs (ibuprofen, naproxen) — they reduce blood flow to kidneys.
- A low-sodium diet (below 2.3g/day) reduces kidney workload and blood pressure.
- Get eGFR rechecked every 6–12 months if it is below 60.
Frequently asked questions about Creatinine / eGFR
What is a dangerously high creatinine level?
Creatinine above 2.0 mg/dL in men or 1.5 mg/dL in women is significantly elevated and warrants urgent evaluation. Creatinine above 5 mg/dL corresponds to eGFR below 15 (kidney failure / end-stage renal disease) and may require dialysis or transplant planning.
Can creatinine levels change day to day?
Yes. Creatinine can fluctuate by 10–15% day to day based on meat intake (creatinine from cooked meat is absorbed), hydration status, exercise intensity, and medication use. A single elevated reading should always be confirmed with a repeat test.
Medical Sources
This page is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider about your individual results.