What is Creatinine?
Creatinine is a waste product produced by muscle metabolism. Healthy kidneys filter creatinine out of the blood and excrete it in urine. When kidneys are damaged or stressed, creatinine builds up in the blood — causing blood creatinine levels to rise. Creatinine is the most commonly tested kidney marker and is part of the standard KFT (Kidney Function Test) panel.
Creatinine Normal Range
| Group | Normal Range (mg/dL) |
|---|---|
| Men | 0.74 – 1.35 |
| Women | 0.59 – 1.04 |
| Children (2–12 yrs) | 0.3 – 0.7 |
| Elderly (>60 yrs) | Slightly lower (less muscle mass) |
What does HIGH creatinine mean?
HIGH Creatinine above 1.4 mg/dL (men) / 1.1 mg/dL (women)
High creatinine (hypercreatininaemia) means the kidneys are not filtering efficiently. Common causes: dehydration (most common — drink more water and retest), chronic kidney disease (CKD from diabetes or hypertension), acute kidney injury (from infection, medication, contrast dye), kidney stones blocking urinary flow, or high muscle mass / high protein diet (minor effect). Always repeat the test after good hydration before concluding kidney disease.
Creatinine above 2.0 mg/dL — Significant kidney impairment
Creatinine above 2 mg/dL usually indicates at least 50% loss of kidney function. Your doctor will calculate eGFR (estimated Glomerular Filtration Rate) which is more accurate than creatinine alone. At this level, kidney ultrasound, urine protein and nephrology referral are typically needed.
What is eGFR and why does it matter more than creatinine?
eGFR — the real measure of kidney function
eGFR (estimated GFR) is calculated from creatinine, age, sex and race. It estimates what percentage of normal kidney function you have. Most labs now report eGFR alongside creatinine.
| eGFR (mL/min/1.73m²) | CKD Stage | Meaning |
|---|---|---|
| >90 | G1 (normal) | Normal kidney function |
| 60–89 | G2 | Mildly reduced |
| 30–59 | G3 | Moderately reduced |
| 15–29 | G4 | Severely reduced |
| <15 | G5 | Kidney failure — dialysis territory |
Questions to ask your doctor
- Could dehydration explain my high creatinine — should I retest after drinking more water?
- What is my eGFR and what stage of CKD does that represent?
- Should I reduce protein intake or avoid NSAIDs (ibuprofen)?
- Do I need to see a nephrologist?