Quick answer: A 50-year-old man with a serum creatinine of 1.0 mg/dL (88 µmol/L) has an eGFR of about 92 mL/min/1.73 m² by CKD-EPI 2021, category G1.
How it's calculated
eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age, multiplied by 1.012 for women. Scr is serum creatinine in mg/dL; κ is 0.7 for women and 0.9 for men; α is −0.241 for women and −0.302 for men. Creatinine in µmol/L is divided by 88.4 to give mg/dL.
The 2021 version removed the race coefficient of earlier CKD-EPI equations and is the one recommended by the US National Kidney Foundation and the American Society of Nephrology. Some calculators still use the 2009 CKD-EPI or the MDRD equation, which give lower values: for a 50-year-old man with creatinine 1.0 mg/dL, 2009 gives about 87 and MDRD about 79, against 92 here.
The result is scaled to a standard body surface area of 1.73 m² and grouped into the KDIGO categories G1 to G5. A low eGFR on a single test is confirmed by repeating it; chronic kidney disease means a reduced eGFR or kidney damage for more than three months.
Creatinine depends on muscle mass and diet, so the estimate is less reliable in people with very high or very low muscle, amputations, pregnancy, acute illness or rapidly changing kidney function. It cannot show the cause of reduced filtration; urine albumin and other tests are needed for that.
Worked examples
- Man, 50, creatinine 1.0 mg/dL: 142 × (1.0/0.9)^−1.200 × 0.9938^50 = 92
- Woman, 50, creatinine 0.7 mg/dL: 142 × 1 × 0.9938^50 × 1.012 = 105
- Woman, 60, creatinine 106 µmol/L (1.2 mg/dL): 142 × (1.2/0.7)^−1.200 × 0.9938^60 × 1.012 = 52 (G3a)
Frequently asked questions
What is a normal eGFR?
90 or above is normal. It falls slowly with age, so values of 60 to 89 are common in older adults and count as kidney disease only with other signs of damage.
How do I convert creatinine from µmol/L to mg/dL?
Divide by 88.4. For example, 88 µmol/L is about 1.0 mg/dL.
Why does my lab report a slightly different number?
Labs may use a different equation (MDRD, CKD-EPI 2009, or a cystatin C equation) or round differently. Results above 60 are often reported only as "> 60" or "> 90".
Can I use this for children?
No. Children's kidney function is estimated with pediatric equations such as the bedside Schwartz formula.
Does one low result mean kidney disease?
Not on its own. Chronic kidney disease is usually diagnosed when eGFR stays under 60 for at least 3 months, or when there are other signs of kidney damage.
What can change creatinine for a short time?
Dehydration, a large meat meal, hard exercise and some medicines can all raise it. Very high or very low muscle mass can also make eGFR less accurate.