Lab result explainedKidneyLast updated November 1, 2026

eGFR blood test: what a low eGFR means and the CKD stages explained

Estimated glomerular filtration rate (eGFR) · Comprehensive metabolic panel (CMP) / Basic metabolic panel (BMP), calculated · reported in mL/min/1.73 m²

eGFR, the estimated glomerular filtration rate, is a calculated number that estimates how many millilitres of blood your kidneys filter each minute, scaled to a standard body size (mL/min/1.73 m²). An eGFR of 90 or above is normal, 60 to 89 is mildly reduced and often fine with age, and below 60 for more than three months defines chronic kidney disease. The two most common reasons it is low are long-standing diabetes and high blood pressure; the most common reasons it is falsely low are high muscle mass and a creatinine raised by creatine, cooked meat or dehydration.

The lab does not measure eGFR directly. It takes your creatinine, age and sex and runs them through an equation (since 2021, the race-free CKD-EPI formula). That makes eGFR only as reliable as the creatinine behind it, which is why clinicians read it with a urine albumin test and, when muscle mass is unusual, a cystatin C.

A single low eGFR is a prompt to look closer, not a verdict. Many people see a value of 55 to 65, worry about kidney failure, and then find on repeat that it was a dehydrated or post-workout sample. This page explains what the number means at each stage, what pushes it down, what is genuinely reversible, and when it needs a nephrologist.

eGFR at a glance

  • What it is: an estimate of kidney filtration calculated from creatinine, age and sex, in mL/min/1.73 m².
  • Normal: 90 or above; 60 to 89 is mildly reduced and often age-related.
  • Low eGFR: below 60 for 3 months or more is chronic kidney disease (stage 3a 45–59, 3b 30–44, 4 15–29, 5 under 15).
  • Falsely low: high muscle mass, creatine, a cooked-meat meal, dehydration, or drugs like trimethoprim raise creatinine without harming the kidney.
  • High eGFR: above 120 can reflect low muscle mass, pregnancy or early diabetic hyperfiltration; rarely a concern.
  • Next step: repeat in 1 to 3 months with a urine albumin-to-creatinine ratio; add cystatin C if muscle mass is unusual.

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What eGFR measures

The glomeruli are the roughly one million tiny filters in each kidney. The true GFR, the volume of plasma they filter per minute, can be measured by injecting a tracer and timing its clearance, but that is slow and expensive. Instead labs estimate it from creatinine, a muscle waste product cleared almost entirely by filtration. Higher creatinine implies lower filtration.

The 2021 CKD-EPI creatinine equation adjusts for age and sex, since older people and women generally have less muscle and therefore less creatinine for the same filtration. It no longer includes a race coefficient. A combined creatinine-cystatin C equation is more accurate and is recommended when the creatinine-based result may mislead or when a treatment decision depends on it.

Reports usually show eGFR as a number up to 90 or 120; values above that are often printed as 'greater than 90' or 'greater than 60' because the equation is less precise at the high end. An eGFR is an estimate with a margin of error of roughly plus or minus 15 to 20 percent, so a shift from 62 to 58 is within noise.

Normal range for eGFR

Reference ranges vary between labs and by age, sex and pregnancy. Use the range printed on your own report.

GroupTypical range (mL/min/1.73 m²)Notes
G1 — normal or high90 or aboveCKD only if there is also kidney damage such as albuminuria or abnormal imaging.
G2 — mildly decreased60–89Common after age 60; not CKD without a damage marker.
G3a — mildly to moderately decreased45–59CKD stage 3a if persistent for 3 months.
G3b — moderately to severely decreased30–44CKD stage 3b; nephrology referral is usual.
G4 — severely decreased15–29CKD stage 4; planning for kidney replacement begins.
G5 — kidney failurebelow 15Dialysis or transplant discussion.
Healthy adults by age~115 at 20–29, ~100 at 40–49, ~85 at 60–69, ~75 at 70+Filtration falls about 1 mL/min per year after 40.

High eGFR

A high eGFR, typically above 120, is usually not a problem. The equation gives high values when creatinine is low, which most often means low muscle mass rather than unusually strong kidneys. Pregnancy also raises true filtration by 40 to 50 percent.

The one situation where a high eGFR has clinical meaning is hyperfiltration in early diabetes or obesity. The kidneys work harder than normal under high pressure, which over years can lead to damage. It is a reason to check urine albumin and manage blood sugar, not an emergency.

Because eGFR equations lose precision above 90, many labs print 'greater than 90' rather than a number, and small differences at the high end should not be over-interpreted.

Common causes

  1. Low muscle mass

    Frailty, sarcopenia, limb loss or small body size lower creatinine production, which the equation reads as high filtration. Cystatin C corrects for this.

  2. Pregnancy

    Plasma volume and renal blood flow increase from the first trimester, raising true GFR; creatinine of 0.4 to 0.6 mg/dL and eGFR well above 120 are normal.

  3. Early diabetic hyperfiltration

    High glucose raises pressure within the glomeruli and increases filtration before damage develops. Albuminuria often follows if glucose is not controlled.

  4. Obesity

    Larger body mass increases absolute filtration demand; eGFR indexed to 1.73 m² can read high before any damage.

  5. High-protein diet or protein loading

    Protein-rich meals and very high protein intakes raise filtration for several hours, a normal physiological response.

  6. Very low creatinine from liver disease or malnutrition

    Reduced creatine synthesis and muscle loss lower creatinine, inflating eGFR and sometimes masking real kidney impairment in cirrhosis.

Symptoms that can go with it

  • Almost always none
  • Foamy urine if hyperfiltration has progressed to albuminuria
  • Thirst, frequent urination or blurred vision if undiagnosed diabetes is the driver
  • Loss of strength or thin limbs if low muscle mass is the reason

Low eGFR

An eGFR below 60 means the kidneys are estimated to be filtering less than about 60 percent of normal. If that persists for three months or more, it meets the definition of chronic kidney disease. Between 60 and 89 is mildly reduced; in someone over 60 with no protein in the urine and normal imaging, it is usually part of normal ageing.

The first job is to decide whether the number is real and whether it is new. A dehydrated, post-workout or creatine-influenced sample can read 10 to 20 points low. A sudden fall from a known baseline is acute kidney injury and needs same-week attention; a slow drift over years is the usual course of CKD and is managed in primary care until stage 3b or 4.

At every stage the strongest predictor of what happens next is urine albumin. An eGFR of 50 with no albuminuria carries a modest risk of progression; the same eGFR with a UACR above 300 mg/g carries a high one. The KDIGO 'heat map' combines both to guide how often to test and when to refer.

Common causes

  1. Diabetes

    High glucose damages the glomerular filters and the small vessels that feed them over years. Diabetic kidney disease is the leading cause of CKD in the US and usually shows albuminuria before eGFR falls.

  2. High blood pressure

    Sustained pressure scars the glomeruli and narrows the kidney's arterioles, slowly reducing filtration. It is the second most common cause and also accelerates every other cause.

  3. Dehydration and acute illness

    Low blood volume reduces renal blood flow and temporarily raises creatinine. A stomach bug or a hot day can drop a calculated eGFR by 10 to 20 points, recovering within days.

  4. High muscle mass, creatine or cooked meat

    All raise creatinine without reducing filtration. A muscular person on creatine who ate steak the night before can show an eGFR in the 60s with completely normal kidneys; cystatin C stays normal.

  5. Medicines

    NSAIDs reduce kidney blood flow and can cause real injury; ACE inhibitors, ARBs and SGLT2 inhibitors cause an expected small, stable drop of up to 30 percent that is protective long-term; trimethoprim and cimetidine raise creatinine without affecting filtration.

  6. Age-related decline

    Filtration falls by roughly 1 mL/min per year after 40. An eGFR of 65 at 80 with no albuminuria is common and carries little excess risk.

  7. Glomerulonephritis and autoimmune disease

    Lupus, IgA nephropathy, vasculitis and other immune diseases inflame the filters. Blood and protein in the urine are the usual clues.

  8. Polycystic kidney disease

    An inherited condition in which fluid-filled cysts gradually replace working kidney tissue; often there is a family history and high blood pressure in young adulthood.

  9. Urinary obstruction

    An enlarged prostate, stones or a tumour blocking outflow raises pressure in the kidney and lowers filtration; it is reversible if relieved early.

  10. Heart failure and cirrhosis

    Reduced effective circulation lowers kidney perfusion; eGFR can improve when the heart or liver condition is treated.

Symptoms that can go with it

  • Usually none until eGFR is below about 30
  • Fatigue, poor concentration and reduced appetite
  • Swelling of the ankles, feet or around the eyes
  • Foamy urine, blood in the urine, or urinating more at night
  • Rising blood pressure
  • Itching, nausea, muscle cramps and a metallic taste in stage 4 to 5
  • Shortness of breath from fluid or anemia in advanced disease

Read it alongside

  • Creatinine — the raw input; check whether anything non-kidney (muscle, creatine, meat, dehydration, trimethoprim) could have raised it.
  • Urine albumin-to-creatinine ratio (UACR) — the second axis of CKD staging; albuminuria predicts progression and cardiovascular risk independently of eGFR.
  • Cystatin C — a muscle-independent filtration marker; a combined creatinine-cystatin eGFR is the most accurate estimate and should be used when the two disagree.
  • BUN and BUN/creatinine ratio — a high ratio points to dehydration or bleeding as the reason the eGFR dipped.
  • Potassium, CO2 (bicarbonate) and phosphate — abnormalities signal that reduced filtration is affecting body chemistry and change management.
  • Hemoglobin — anemia from reduced erythropoietin typically appears below an eGFR of 45 and supports a chronic process.
  • A1C and blood pressure — the two drivers that most often explain and most often fix a falling eGFR.

What usually happens next

  1. A first eGFR below 60 is repeated within a few weeks (sooner if it is far below your previous value), fasting, well hydrated, off creatine and without heavy exercise or cooked meat the day before.
  2. A urine albumin-to-creatinine ratio is added if not already done; a urinalysis checks for blood and casts.
  3. If muscle mass is unusually high or low, or if a decision about medication or referral depends on the number, ask for cystatin C and a combined eGFR.
  4. Medicines are reviewed and doses adjusted for kidney function; NSAIDs are stopped where possible.
  5. A kidney ultrasound is arranged if obstruction, cysts, stones or a very rapid decline are possible.
  6. Referral to a nephrologist is usual for an eGFR below 30, a UACR above 300 mg/g, a fall of more than 25 percent or 5 mL/min per year, blood in the urine with no urological cause, or unclear diagnosis.

Diet, lifestyle and natural levers with evidence

What can move eGFR once the cause is known. Nothing here replaces finding the cause.

Blood pressure control, including sodium under 2 g a day

Strong evidence

High blood pressure both causes and accelerates kidney decline. Sodium restriction lowers systolic pressure by around 4 to 6 mmHg in trials and amplifies the kidney-protective effect of ACE inhibitors and ARBs. KDIGO recommends sodium below 2 g (about 5 g of salt) daily and a target systolic pressure under 120 for most adults with CKD.

DASH or Mediterranean-style diet

Moderate evidence

In the ARIC cohort, adults most adherent to a DASH pattern had a 45 percent lower risk of incident CKD over 23 years. A meta-analysis of cohort studies in people with CKD found healthy dietary patterns were associated with about 30 percent lower mortality. These diets lower acid load, blood pressure and glucose, three of the main drivers of eGFR loss.

Fruit and vegetables to reduce acid load

Moderate evidence

In randomised trials in CKD stage 3 and 4 with low bicarbonate, adding 2 to 4 cups of fruit and vegetables a day was as effective as oral sodium bicarbonate at correcting acidosis and was associated with slower eGFR decline over 3 to 5 years, with lower blood pressure as a bonus.

In stage 4 to 5 CKD, potassium must be monitored; do this with a renal dietitian.

Regular physical activity and weight management

Moderate evidence

Meta-analyses of exercise trials in CKD show improved blood pressure, fitness and quality of life, with small improvements in eGFR in some studies. Weight loss of 5 to 10 percent in people with obesity reduces albuminuria and hyperfiltration. The main mechanism is better blood pressure and glucose control.

Avoid very intense sessions for 24 to 48 hours before a blood test; they raise creatinine temporarily.

Stop smoking

Strong evidence

Smoking roughly doubles the rate of eGFR decline in people with diabetic and hypertensive kidney disease and increases albuminuria. Cohort studies show the rate of decline falls toward that of non-smokers within a few years of quitting. It is the single lifestyle change with the largest effect on both kidney and heart outcomes.

Avoid NSAIDs and kidney-toxic supplements

Strong evidence

Regular NSAID use is associated with faster eGFR decline and acute kidney injury, especially combined with diuretics and ACE inhibitors. Herbal products containing aristolochic acid (some traditional Chinese formulas) cause irreversible kidney damage, and high-dose vitamin C, creatine loading and some bodybuilding products can distort or stress kidney function. Check every supplement with your clinician if your eGFR is under 60.

When to see a clinician promptly

  • An eGFR below 30, or below 45 for the first time, should be discussed within days.
  • A fall of more than 25 percent from your previous eGFR, or a creatinine rise of 0.3 mg/dL or more within 48 hours, is acute kidney injury until proven otherwise.
  • Passing very little urine, or none, for 8 to 12 hours, especially after vomiting, diarrhea, contrast dye or a new medicine.
  • Swelling of the legs or face with breathlessness, or chest pain, alongside a low eGFR.
  • Blood in the urine, or foamy urine with a low eGFR, which suggests active glomerular disease.
  • A potassium above 5.5 mmol/L or bicarbonate below 18 on the same report; these need same-day review.

Frequently asked questions

What is a normal eGFR?

An eGFR of 90 or above is normal. Values of 60 to 89 are mildly reduced and are common and usually harmless after age 60 if there is no protein in the urine. Filtration falls by about 1 mL/min per year after 40, so a healthy 75-year-old often sits in the 70s.

Is an eGFR of 60 bad?

An eGFR of exactly 60 sits on the boundary. On its own, especially in someone over 60 with no albuminuria, it is mildly reduced and low risk. It becomes stage 3a CKD only if a repeat test three months later is still below 60. Your clinician will check a urine albumin test, your blood pressure and glucose, and whether muscle, creatine, cooked meat or dehydration skewed the sample.

What are the CKD stages by eGFR?

Stage 1 is an eGFR of 90 or above with kidney damage, stage 2 is 60 to 89 with damage, stage 3a is 45 to 59, stage 3b is 30 to 44, stage 4 is 15 to 29 and stage 5 is below 15. Each stage is further graded by urine albumin (A1 under 30 mg/g, A2 30 to 300, A3 above 300). The combination, not the eGFR alone, sets the risk.

Can eGFR go back up?

Yes, when the cause is reversible: dehydration, an NSAID, a urinary blockage, uncontrolled blood pressure or a creatinine artefact from creatine or cooked meat. Scarred kidney tissue does not regrow, so in long-standing CKD the realistic goal is to slow or stop the decline. Good blood pressure and glucose control, SGLT2 inhibitors and diet can hold an eGFR steady for years.

Can muscle mass or creatine make my eGFR look low?

Yes. eGFR is calculated from creatinine, which rises with muscle mass and with creatine supplements. A muscular person on creatine can have an eGFR in the 60s with normal kidneys. Ask for a cystatin C test, which does not depend on muscle; if the cystatin-based eGFR is normal, your kidneys are fine.

What is the difference between GFR and eGFR?

GFR is the true filtration rate, measured by clearing a tracer such as iohexol or inulin from the blood. eGFR is an estimate of that number from creatinine or cystatin C using an equation. Measured GFR is used before kidney donation and in some drug dosing; for everyday care eGFR is accurate enough.

How often should eGFR be checked?

Once a year is typical for stable stage 1 to 3a disease with little albuminuria, every 6 months for stage 3b, and every 3 months for stage 4 or heavy albuminuria. People with diabetes or high blood pressure and a normal eGFR should still have an eGFR and urine albumin test once a year.

Does a high eGFR mean anything?

Usually not. Values above 120 most often reflect low muscle mass or pregnancy. In early diabetes or obesity a high eGFR can represent hyperfiltration, which is a reason to check urine albumin and manage glucose and weight, but it does not itself cause symptoms or need treatment.

References

  1. Glomerular Filtration Rate (GFR) Test. MedlinePlus, US National Library of MedicineView source
  2. Estimated Glomerular Filtration Rate (eGFR). National Kidney FoundationView source
  3. Inker LA, Eneanya ND, Coresh J, et al.. New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race. New England Journal of Medicine (2021)View source
  4. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney International (2024)View source
  5. Gaitonde DY, Cook DL, Rivera IM. Chronic Kidney Disease: Detection and Evaluation. American Family Physician (2017)
  6. Chronic kidney disease. Mayo ClinicView source
  7. Chronic Kidney Disease in the United States. Centers for Disease Control and PreventionView source
  8. Rebholz CM, Crews DC, Grams ME, et al.. DASH (Dietary Approaches to Stop Hypertension) Diet and Risk of Subsequent Kidney Disease. American Journal of Kidney Diseases (2016)
  9. Kelly JT, Palmer SC, Wai SN, et al.. Healthy Dietary Patterns and Risk of Mortality and ESRD in CKD: A Meta-Analysis of Cohort Studies. Clinical Journal of the American Society of Nephrology (2017)
  10. Goraya N, Simoni J, Jo CH, Wesson DE. Treatment of metabolic acidosis in patients with stage 3 chronic kidney disease with fruits and vegetables or oral bicarbonate reduces urine angiotensinogen and preserves glomerular filtration rate. Kidney International (2014)
  11. Preiss DJ, Godber IM, Lamb EJ, Dalton RN, Gunn IR. The influence of a cooked-meat meal on creatinine plasma concentration and estimated glomerular filtration rate. Annals of Clinical Biochemistry (2007)
  12. Clark WF, Sontrop JM, Huang SH, et al.. Effect of Coaching to Increase Water Intake on Kidney Function Decline in Adults With Chronic Kidney Disease: The CKD WIT Randomized Clinical Trial. JAMA (2018)View source

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This page is educational and is not medical advice or a diagnosis. Lab results have to be interpreted together with your history, symptoms and other results by a clinician who knows you. Do not start or stop a supplement to change a lab value before the cause is known.