Lab Test

Kidney Function Tests: eGFR, Creatinine & What They Mean

Kidney function tests assess how well your kidneys filter waste and protein. The eGFR and urine albumin-creatinine ratio (ACR) together stage chronic kidney disease and guide management.

Normal eGFR
>60 mL/min/1.73m²
CKD diagnosis
eGFR <60 for >3 months
Urine ACR (normal)
<3 mg/mmol
CKD global prevalence
~10% of population

Key Tests in a Kidney Panel

TestNormal ValueWhat It Shows
eGFR≥60 mL/min/1.73m²Estimated glomerular filtration rate — kidney filtering capacity
Creatinine60–110 μmol/LMuscle waste product cleared by kidneys — rises when GFR falls
Urea2.5–7.8 mmol/LNitrogen waste from protein metabolism — less specific than creatinine
Urine ACR (albumin:creatinine ratio)<3 mg/mmolProtein leak into urine — early kidney damage marker
Urine PCR (protein:creatinine ratio)<15 mg/mmolMore complete urine protein measurement
Cystatin C0.5–1.0 mg/LAlternative GFR marker; less affected by muscle mass

CKD Staging by eGFR

CKD StageeGFR (mL/min/1.73m²)Significance
G1≥90 (with kidney damage markers)Normal GFR but kidney damage present
G260–89Mildly reduced
G3a45–59Mildly-moderately reduced
G3b30–44Moderately-severely reduced
G415–29Severely reduced — plan for renal replacement therapy
G5<15Kidney failure — dialysis or transplant
eGFR + ACR TogetherCKD is diagnosed by either low eGFR OR evidence of kidney damage (raised ACR, blood/protein in urine, structural abnormality). An eGFR of 55 with ACR of 10 is worse prognosis than eGFR 55 with normal ACR.
Is eGFR 55 serious?
eGFR 55 (CKD stage G3a) represents mildly-to-moderately reduced kidney function. Many people remain stable for years. Control of blood pressure and diabetes, avoiding nephrotoxic drugs, and annual monitoring are key.
Can creatinine be high without kidney disease?
Yes — high muscle mass (bodybuilders, young men) raises creatinine without kidney disease. Dehydration also temporarily raises creatinine. Cystatin C is more reliable in these situations.
What causes protein in urine?
Common causes: diabetes (diabetic nephropathy), hypertension, glomerulonephritis, UTI (transient), pre-eclampsia in pregnancy, multiple myeloma, and nephrotic syndrome.
What makes CKD progress faster?
Uncontrolled diabetes and hypertension are the biggest accelerators. NSAIDs, iodinated contrast agents, dehydration, and nephrotoxic antibiotics (aminoglycosides) also worsen kidney function acutely.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.