What Does eGFR Mean? Kidney Function, CKD Stages, and Next Steps

eGFR means estimated glomerular filtration rate. It is an estimate of how well your kidneys filter blood and remove waste and extra fluid. A laboratory usually calculates it from serum creatinine plus age and sex; some clinicians use cystatin C, alone or with creatinine, when that may give a clearer estimate. It is a blood-test result, not a symptom score. NIDDK explains how eGFR is estimated.

The number is reported in mL/min/1.73 m². A higher number generally means more estimated filtration, but eGFR is not a direct measurement of every part of kidney function and it is not an exact percentage of working kidneys. A result of 45 does not mean that exactly 45% of your kidneys are working. The equation is an estimate and can be less reliable when creatinine is changing quickly or when muscle mass, diet, or other factors make creatinine unusual. The National Kidney Foundation describes eGFR and its limits.

eGFR is only one half of the usual CKD picture. The other key marker is the urine albumin-to-creatinine ratio, or uACR, which measures albumin in urine. Albumin is a specific protein; uACR is not the same as a general “urine protein” result. Your clinician combines eGFR, uACR, the possible cause, symptoms, and change over time. NIDDK's reference explains why both markers matter.

CKD is not diagnosed by an eGFR label alone. KDIGO classifies CKD by Cause, GFR category, and Albuminuria category, often shortened to CGA. The G category describes estimated filtration; the A category describes urine albumin. Abnormalities generally need to be present for at least three months to meet the definition of chronic kidney disease. KDIGO's 2024 CKD guideline sets out the G and A categories.

The G categories

• G1: eGFR ≥90 mL/min/1.73 m². This is normal or high filtration; CKD requires a separate marker of kidney damage that persists for at least three months.

• G2: 60–89 mL/min/1.73 m². This is mildly decreased; as with G1, an eGFR in this range alone does not establish CKD.

• G3a: 45–59 mL/min/1.73 m². This is mildly to moderately decreased filtration.

• G3b: 30–44 mL/min/1.73 m². This is moderately to severely decreased filtration.

• G4: 15–29 mL/min/1.73 m². This is severely decreased filtration; clinicians usually review complications and kidney-care planning.

• G5: below 15 mL/min/1.73 m². This is the kidney failure range. Dialysis or transplant may be considered based on symptoms, complications, and the whole clinical picture—not the number alone. Read what starting dialysis can involve.

The A category adds urine albumin

uACR measures albumin, a type of protein, against creatinine in a urine sample. KDIGO categories are A1: <30 mg/g (<3 mg/mmol), A2: 30–300 mg/g (3–30 mg/mmol), and A3: >300 mg/g (>30 mg/mmol). A higher uACR can signal more kidney damage and higher risk, but a single result can be affected by temporary factors and may need confirmation. The CDC explains how urine albumin testing fits with eGFR.

An eGFR ≥60 with uACR <30 mg/g and no other markers of kidney damage may not meet CKD criteria. An eGFR <60 mL/min/1.73 m² that persists for at least three months can meet CKD criteria even if uACR is normal. Your clinician interprets both results rather than treating either one as the whole diagnosis.

Before your appointment, turn one laboratory result into a timeline. Save the report, the date, your eGFR, serum creatinine, uACR, units, and reference range. Previous results—especially when they come from the same laboratory—help your clinician see whether the change is real and how quickly it happened.

Bring this information

• The complete laboratory report, including the eGFR unit, creatinine value, uACR value, and the date of each test.

• Every prescription, over-the-counter medicine, vitamin, and supplement. Include NSAID pain relievers such as ibuprofen or naproxen, even if you take them only occasionally.

• Recent vomiting, diarrhea, fever, infection, poor intake, dehydration, unusual exercise, or a major diet change that happened before the blood test.

• Home blood-pressure or blood-sugar readings if you track them, plus swelling, urine changes, fatigue, nausea, or other symptoms.

• Your kidney history, including previous stones, urinary infections, imaging, or a family history of kidney disease if you know it.

Questions to ask

• Is my eGFR based on creatinine, cystatin C, or both, and how does it compare with my previous results?

• What is my uACR in mg/g or mg/mmol? Do I need a repeat test to confirm it, and has the abnormality lasted three months?

• Could an illness, dehydration, medicine, muscle mass, diet, or normal laboratory variation explain the change?

• What should be checked next: repeat blood or urine tests, imaging, or a nephrologist referral?

• What blood-pressure, blood-sugar, sodium, or potassium plan fits my results? If sodium or potassium is part of the discussion, use the practical guides on sodium and CKD and potassium and CKD as questions to bring to your team, not as a personal prescription.

At follow-up, your clinician tries to work out whether the change is new, temporary, or chronic. They may review your health, medicines, blood pressure, fluid status, and recent illness, then repeat serum creatinine/eGFR and uACR. Depending on the situation, they may also order a urinalysis, electrolytes, blood counts, imaging, or another test to look for a cause. Not everyone needs every test.

If eGFR changed during dehydration, acute illness, or a medicine change, the result may reflect acute kidney injury rather than established CKD. Do not assume that a low result is permanent, but do not dismiss it either. Only your clinician can decide whether a medicine should be adjusted and how soon testing should be repeated.

If a lower eGFR is stable over time, your clinician may focus on the cause, uACR, blood pressure, diabetes, medicines, and complications. The plan may include monitoring, treatment of the cause, medication review, nutrition advice, or a nephrology referral. A kidney diet is not one universal menu; protein, sodium, potassium, and fluid advice depends on your results and treatment.

How follow-up can be organized

1. Confirm the result: repeat blood and urine tests when your clinician recommends them, then compare them with prior values.

2. Look for a cause: review blood pressure, diabetes, medicines, recent illness, urinary blockage, and other conditions; imaging is used when it is appropriate.

3. Estimate risk: combine the eGFR category, uACR, cause, symptoms, and rate of change instead of relying on one number.

4. Set the next checkpoint: know when to repeat tests, which symptoms should prompt an earlier call, and whether a specialist or dietitian is part of the plan.

Many people with reduced eGFR have no symptoms. Symptoms cannot reliably tell you whether a laboratory result is safe. Use the action plan from your care team, and treat the following warning signs seriously.

Seek emergency care now

• Severe or sudden shortness of breath, especially at rest.

• Chest pain, pressure, or tightness.

• Fainting, new confusion, inability to stay awake, or a seizure.

• A new fast or irregular heartbeat with severe weakness, dizziness, or collapse.

• Sudden severe swelling together with trouble breathing.

Call your clinician or kidney team today

• Much less urine than usual, new blood in the urine, or new difficulty passing urine.

• Rapidly worsening swelling or rapid weight gain.

• Repeated vomiting or diarrhea, fever, or being unable to keep fluids or prescribed medicines down.

• A laboratory or clinician tells you that eGFR fell sharply, creatinine rose quickly, or potassium or another result is dangerously abnormal.

• New or worsening fatigue, nausea, or itching when you have a very low eGFR, especially if your team has given you a same-day plan.

What can usually wait for a planned visit

Stable mild fatigue, occasional nighttime urination, or a question about a mildly changed result can usually be written down for your next planned visit when there are no warning signs. Contact the clinic sooner if the symptom worsens, new symptoms appear, or you are unsure what your plan says.

eGFR follow-up is a process, not a one-time verdict. If you miss a laboratory test or appointment, or if a result is delayed, contact the clinic rather than guessing. Do not change your medicines, fluid intake, salt, protein, or supplements based only on an online number.

If follow-up is delayed

1. Call the clinic, give the date and result you have, and ask when the repeat blood and urine tests should happen.

2. Keep an updated medicine and supplement list. Ask before using ibuprofen, naproxen, herbal products, or supplements marketed for kidney health.

3. Track blood pressure and symptoms only as your team recommends. Do not force extra fluids unless a clinician tells you to do so.

4. Bring every result to the next visit and ask for a written plan: the next test date, the target symptoms to report, and the number to call.

Habits that support kidney care

• Take prescribed medicines as directed, and do not stop or change ACE inhibitors, ARBs, diuretics, or other treatment without your clinician's instruction.

• Work with your team on blood pressure and diabetes management; targets are personal and may change with kidney function and other conditions.

• Avoid smoking and choose physical activity that is safe for your health and energy level.

• Ask a renal dietitian before making major changes to sodium, potassium, protein, or fluid. The guides on sodium intake and CKD and potassium and CKD can help you prepare questions.

• Tell every clinician that you have reduced kidney function before starting a new medicine or having a procedure, so they can review doses and risks.