Key Benefits

• See how well your kidneys filter waste and keep your body in balance.
• Spot early kidney stress from diabetes, high blood pressure, dehydration, or medications.
• Explain fatigue, swelling, or poor appetite when kidney function declines.
• Guide safe medication choices and dosing that depend on kidney function levels.
• Protect heart health by flagging kidney-related cardiovascular risk for earlier prevention.
• Support fertility and pregnancy planning by highlighting kidney issues before conception.
• Track long-term trends to confirm chronic disease and monitor response to care.
• Best interpreted with urine albumin-to-creatinine ratio, blood pressure, and your symptoms.

What is Estimated Glomerular Filtration Rate (eGFR)?

Estimated glomerular filtration rate is a calculated snapshot of how much blood your kidneys filter each minute. It is not a substance in your blood, but a value inferred from routine blood markers—most often creatinine, sometimes cystatin C—together with basic personal characteristics. The number is meant to approximate your true filtration capacity across millions of tiny kidney filters (glomeruli) within the functional units of the kidney (nephrons), where blood plasma is strained to begin urine formation.

eGFR distills kidney performance into one understandable figure. It reflects how effectively your kidneys clear everyday metabolic wastes, keep body water and salts in balance, and help stabilize acid–base status (homeostasis of electrolytes and pH). Because filtration at the glomerulus underpins many downstream kidney tasks, eGFR also ties into broader body functions—supporting blood pressure regulation (renin–angiotensin system), activating vitamin D for bone health (calcitriol), and enabling healthy red blood cell production (erythropoietin). In short, eGFR indicates the kidneys’ filtering power and the reserve that helps your body stay chemically steady.

Why is Estimated Glomerular Filtration Rate (eGFR) important?

Estimated glomerular filtration rate (eGFR) is your kidneys’ overall filtering capacity—how effectively they clear wastes, balance fluids and electrolytes, regulate acid–base status, and support hormones that affect blood pressure, red blood cell production, and bone health. It’s calculated from blood markers (creatinine or cystatin C) together with age and sex. In healthy young adults, values around 90–120 are typical; above 60 is generally adequate. Optimal tends to sit at the higher end for your age.

When eGFR runs low, fewer functioning nephrons are filtering. Waste products and acids accumulate, salt and water are retained, and potassium may rise. The kidneys make less active vitamin D and erythropoietin, weakening bones and lowering red blood cells. People may feel fine at first, then develop fatigue, swelling, high blood pressure, itching, muscle cramps, shortness of breath, poor appetite, or nighttime urination. Persistent values below 60 signal chronic kidney disease; below 15 reflects kidney failure. eGFR naturally declines with age, so older adults may sit between 60–89 without other signs of disease; albumin in the urine clarifies the picture.

When eGFR seems high, it can be normal in youth and rises during pregnancy as kidney blood flow increases. Outside these settings, “hyperfiltration” often reflects early diabetic or obesity-related kidney stress—high pressure across glomeruli that can precede albumin leakage and later decline.

Big picture: eGFR anchors kidney health and closely tracks cardiovascular risk, blood pressure control, mineral–bone balance, cognition, and medication handling. Interpreted with urine albumin and context, it helps anticipate long-term risks of heart disease, fractures, anemia, and progression to kidney failure.

What Insights Will I Get?

Estimated Glomerular Filtration Rate (eGFR) estimates how much blood your kidneys filter each minute. It is a window into whole‑body homeostasis—how you clear metabolic waste, balance fluids, electrolytes, and acids, regulate blood pressure (renin‑angiotensin system), support red blood cell production (erythropoietin), and maintain bone‑mineral balance. Because these processes influence cardiovascular risk, energy, cognition, and immunity, eGFR is a systems health marker, not just a kidney number.

Low values usually reflect reduced kidney filtering capacity (impaired glomerular function), from fewer working nephrons or reduced kidney blood flow. System-level effects can include fluid and salt retention, higher blood pressure, acid‑base and potassium imbalance, anemia, and mineral‑bone changes, with downstream effects on cognition, appetite, and fertility. eGFR declines with age; in pregnancy, filtration normally rises, so a “low” value is more concerning.

Being in range suggests adequate filtration reserve and a stable internal environment—steady electrolytes and acid‑base status, appropriate blood pressure signaling, and predictable drug handling. In general, risk profiles are most favorable when eGFR sits in the upper part of the reference range, provided urine tests show no kidney damage.

High values usually reflect increased filtration (hyperfiltration). This can be normal in early pregnancy or occur with states of high kidney blood flow; it may also result from overestimation when creatinine is low due to low muscle mass. Persistent hyperfiltration can precede albumin leakage and future loss of kidney function.

Notes: eGFR is an estimate derived from creatinine and/or cystatin C with age and sex; muscle mass, acute illness, medications that affect creatinine handling, and hydration can shift results. Equations vary (many now avoid race terms), and pediatric values use different formulas.