Kidney Biomarker
Collection Type: Blood
Related System: Kidney
Glomerular Filtration Rate (GFR) measures how much blood the kidneys filter each minute, normalized to body surface area (mL/min/1.73 m²). It is estimated (eGFR) from blood creatinine (and sometimes cystatin C), age, sex and body size to assess kidney function. Low GFR suggests reduced kidney clearance and may indicate chronic kidney disease (CKD), acute kidney injury (AKI), or urinary obstruction. Symptoms that prompt testing include reduced urine output, swelling (edema), fatigue, poor appetite, foamy or bloody urine, or abnormal blood tests. GFR normally declines with age; women and people with low muscle mass may have lower creatinine and different eGFR estimates. Pregnancy and high muscle mass can raise measured filtration.
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Symptom Checker90-120 mL/min/1.73 m²
Q: What is a normal glomerular filtration rate?
A: A normal glomerular filtration rate (GFR) in adults is about ≥90 mL/min/1.73 m², indicating healthy kidney function. Values 60–89 mL/min/1.73 m² suggest mildly reduced GFR (often age-related) if there are no other signs of kidney damage, while <60 mL/min/1.73 m² for three months or more signals chronic kidney disease. GFR is estimated from serum creatinine, age, sex and body surface area.
Q: What is the glomerular filtration rate?
A: Glomerular filtration rate (GFR) measures how much blood is filtered by the kidney’s glomeruli per minute, expressed as mL/min/1.73 m². eGFR is estimated from serum creatinine, age, sex and body size. Normal GFR is roughly 90–120 mL/min/1.73 m²; lower values indicate impaired kidney function and help stage acute or chronic kidney disease, guiding diagnosis and treatment.
Q: What level of eGFR indicates kidney failure?
A: An eGFR below 15 mL/min/1.73 m² is generally considered kidney failure (stage 5 chronic kidney disease). At this level the kidneys cannot adequately clear waste and patients often require dialysis or transplantation. Clinical context, symptoms, and trends over time determine management; transient low values should be confirmed and evaluated by a healthcare professional.
Q: What is a high glomerular filtration rate?
A: A high glomerular filtration rate (GFR) is when estimated filtration exceeds the normal range (typically above about 120–130 mL/min/1.73 m²). It often reflects glomerular hyperfiltration from early diabetes, pregnancy, high protein intake, or certain medications, and can indicate increased kidney workload that may precede damage; interpretation requires clinical context and repeat testing.
Q: Can drinking water improve GFR?
A: Drinking water can temporarily increase GFR by restoring blood volume and improving kidney perfusion, especially if you are mildly dehydrated. For people with normal kidneys, staying well hydrated supports filtration. However, in chronic kidney disease or heart failure, extra fluids won’t reverse long-term GFR decline and can be harmful—follow a clinician’s guidance on fluid intake and any specific restrictions.
Q: What is a normal GFR for a 70 year old?
A: A normal estimated GFR for a healthy 70‑year‑old is lower than in younger adults—typically about 60–75 mL/min/1.73 m². Values at or above 60 are usually considered acceptable for older adults; persistent readings below 60 suggest possible chronic kidney disease and should prompt further evaluation, especially if accompanied by protein in the urine or other kidney-related signs.