Low eGFR: Symptoms, Causes, and What the Result Means

A low eGFR usually causes no symptoms until kidney function is well reduced. Learn the eGFR stages, the temporary causes of a falsely low result, and when to retest or follow up.

Published

October 5, 2026

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8 min read

Medically reviewed by

Rhonda Collins, FNP-C

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A low eGFR means your estimated glomerular filtration rate is below 60 mL/min/1.73m². When it stays there for more than 3 months, it meets the definition of chronic kidney disease (CKD) in the KDIGO 2024 guideline. Most people with a low eGFR feel nothing. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) notes that many people have no symptoms until kidney disease is advanced, which is why a low eGFR is almost always found on a routine blood test. A single low result can also be temporary or falsely low, so it is usually confirmed before anyone calls it kidney disease.

The eGFR biomarker overview explains what eGFR is and how it is calculated from creatinine. This page covers what a low result means, what can cause it, and what to do next.

What Counts as a Low eGFR

KDIGO, the international kidney guideline group, sorts eGFR into six categories. The National Kidney Foundation uses the same stages.

Three points shape how to read the table:

• Below 60 is the CKD threshold. KDIGO defines CKD as an eGFR below 60, or signs of kidney damage such as albumin in the urine, lasting more than 3 months. An eGFR of 60 to 89 with no kidney damage markers does not meet the criteria for CKD.
• eGFR tends to decline with age. The National Kidney Foundation notes that a low eGFR in an older person does not always mean CKD, even when it is below 60. KDIGO describes an average age-related decline with substantial variation between individuals.
• The US standard is a race-free equation. Since 2021, the National Kidney Foundation and the American Society of Nephrology have recommended the CKD-EPI 2021 creatinine equation, which estimates GFR from creatinine, age, and sex without a race term.

Does a Low eGFR Cause Symptoms?

Usually not, especially in stages G2 and G3. NIDDK states that most people in the early stages of CKD do not have symptoms. Swelling in the legs, feet, or ankles is one sign that can appear earlier, when the kidneys start to hold on to extra fluid.

A low eGFR on its own is therefore not explained by, and does not explain, everyday tiredness or aches. If you feel unwell and your eGFR is only mildly low, the symptoms are more likely to have another cause worth looking into.

Symptoms at Lower eGFR Levels

Symptoms tend to appear once kidney disease is advanced, generally in stages G4 and G5, as waste and fluid build up in the body. NIDDK lists these signs of advanced CKD:

• tiredness or trouble sleeping;
• loss of appetite, nausea, or vomiting;
• trouble concentrating;
• a change in how often you urinate, or foamy urine;
• itching, numbness, dry skin, or darkened skin;
• muscle cramps;
• unintended weight loss;
• chest pain or shortness of breath;
• worsening swelling in the legs, feet, or ankles.

A sudden drop is different. Acute kidney injury can lower eGFR suddenly. MedlinePlus advises contacting a provider promptly if urine output slows or stops, or if you have other signs such as blood in the urine, persistent nausea or vomiting, or new swelling.

Common Causes of a Low eGFR

A low eGFR has two broad kinds of cause: lasting kidney damage, and factors that lower the number temporarily or make the creatinine-based estimate read low.

Chronic kidney disease

NIDDK names diabetes and high blood pressure as the most common causes of CKD in adults. Other causes include:

• glomerular diseases such as IgA nephropathy and focal segmental glomerulosclerosis;
• polycystic kidney disease and other inherited conditions such as Alport syndrome;
• autoimmune disease such as lupus;
• repeated or severe acute kidney injury, kidney stones with complications, or medicines that are toxic to the kidneys;
• renal artery stenosis, severe obesity, and sickle cell disease.

Temporary or falsely low results

eGFR is calculated from blood creatinine. Anything that raises creatinine without changing true kidney filtration lowers the eGFR. Anything that briefly reduces blood flow to the kidneys lowers true filtration for a while.

• Dehydration and acute illness. MedlinePlus lists dehydration as a cause of high creatinine, and very low blood pressure from dehydration, serious illness, or surgery as a cause of acute kidney injury.
• A recent meat or fish meal. KDIGO cites a study in which a cooked meat meal raised serum creatinine by about 0.23 mg/dL, equivalent to roughly 20 mL/min/1.73m² less eGFR in that study population. KDIGO notes that waiting at least 12 hours after meat or fish best avoids the effect.
• Creatine supplements and high-protein diets. KDIGO lists both as factors that raise creatinine independently of kidney function.
• High muscle mass. Muscle produces creatinine, so bodybuilders and very muscular people can have a higher creatinine and a lower eGFR with normal kidneys. KDIGO names extreme exercise and body building as situations where creatinine-based eGFR is less accurate.
• Medicines that block creatinine secretion. Trimethoprim, including in sulfamethoxazole-trimethoprim, reversibly reduces the kidneys’ secretion of creatinine, which raises the creatinine level without lowering true GFR.
• Medicines that change kidney blood flow. ACE inhibitors and ARBs often cause a small, expected dip in eGFR when started. KDIGO describes rises in creatinine of less than 20 to 30 percent as expected and recommends continuing these kidney-protective medicines unless creatinine rises by more than 30 percent within 4 weeks. NSAIDs such as ibuprofen and naproxen can reduce kidney blood flow and lower GFR. A low eGFR is not a reason to stop a prescribed medicine on your own.

The limits of a creatinine-based estimate

Creatinine depends on muscle mass, diet, and some medicines as well as on kidney filtration, so eGFRcr can be wrong in either direction. KDIGO recommends adding cystatin C when the creatinine estimate is likely to be less accurate and the result matters for a decision, for example to confirm a CKD diagnosis. Cystatin C does not depend on muscle mass or diet the way creatinine does, although KDIGO notes it has its own influences, such as higher body fat, smoking, thyroid disease, steroid use, and inflammation. The CKD-EPI 2021 study found that equations combining creatinine and cystatin C were more accurate than either marker alone.

The eGFRcr-cys biomarker overview explains the combined estimate, and the cystatin C overview covers the marker itself. If your creatinine-based eGFR is borderline or you fit one of the situations above, a cystatin C test with eGFR can help confirm whether the low result is real. The eGFRcr vs eGFRcr-cys comparison sets the two estimates side by side.

When to Retest or Follow Up

A single low eGFR is a reason to check again, not a diagnosis. KDIGO’s guidance for a low result found by chance is to repeat the test to confirm it. These steps make the repeat more useful:

• Repeat the test, and look for persistence beyond 3 months. CKD requires a low eGFR or kidney damage lasting more than 3 months. Past results help too, so bring earlier lab reports if you have them.
• Prepare for the draw. Be well hydrated, avoid a large meat or fish meal for 12 hours beforehand, and tell your clinician about creatine supplements and every medicine you take.
• Add a urine albumin test. KDIGO recommends testing both eGFR and the urine albumin-to-creatinine ratio (UACR). Albumin in the urine can show kidney damage while eGFR still looks normal, and together the two set your CKD stage and risk.
• Confirm with cystatin C when creatinine may mislead, as described above.

KDIGO recommends referral to a kidney specialist when:

• eGFR is below 30 mL/min/1.73m²;
• urine albumin is persistently high (ACR of 300 mg/g or more);
• eGFR shows a sustained fall of more than 20 percent, or more than 30 percent after starting a blood pressure or kidney-protective medicine;
• the cause of the kidney disease is uncertain or may be inherited.

The Mito Kidney Panel pairs creatinine-based eGFR with the urine albumin-to-creatinine ratio, the two tests KDIGO uses to detect and stage CKD. For how eGFR fits into long-term kidney health, see eGFR, kidney health, and longevity. Test options and pricing are compared in the kidney function test cost guide.

References

• Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney Int. 2024
• Inker LA, et al. New creatinine- and cystatin C-based equations to estimate GFR without race. N Engl J Med. 2021
• Delgado C, et al. A unifying approach for GFR estimation: recommendations of the NKF-ASN Task Force on reassessing the inclusion of race in diagnosing kidney disease. Am J Kidney Dis. 2022
• NIDDK: What is chronic kidney disease?
• NIDDK: Causes of chronic kidney disease
• National Kidney Foundation: Estimated glomerular filtration rate (eGFR)
• MedlinePlus: Creatinine test
• MedlinePlus: Acute kidney failure

Related Resources

• eGFR (creatinine) biomarker overview
• eGFR (creatinine and cystatin C) biomarker overview
• Cystatin C biomarker overview
• High creatinine symptoms
• How to improve your eGFR naturally
• eGFR, kidney health, and longevity
• Cystatin C test cost guide
• Kidney function test cost guide

Hero photo by Filip Kvasnak on Unsplash.

Frequently asked questions

Is an eGFR of 55 bad?

An eGFR of 55 falls in the G3a range (45 to 59), which KDIGO calls mildly to moderately decreased. It meets the CKD threshold only if it stays below 60 for more than 3 months, so the usual next step is a repeat test plus a urine albumin-to-creatinine ratio. It causes no symptoms at this level for most people. In an older adult, a muscular person, or someone who ate a large meat meal before the draw, a repeat test or a cystatin C based eGFR may read differently.

Can dehydration cause a low eGFR?

Yes. Dehydration can raise blood creatinine, and because eGFR is calculated from creatinine, a higher creatinine reads as a lower eGFR. Severe dehydration can also reduce blood flow to the kidneys and cause acute kidney injury. A low result taken while dehydrated or unwell should be repeated once you are well.

Can a low eGFR go back up?

It depends on the cause. A result lowered by dehydration, a recent meat meal, creatine supplements, or a medicine that blocks creatinine secretion often reads higher on a repeat test once that factor is gone. The small drop that can follow starting an ACE inhibitor or ARB is expected and typically stabilizes or resolves over time. Chronic kidney disease that has lasted more than 3 months is managed to slow further decline rather than expected to return to normal.

What eGFR level is dangerous?

KDIGO classifies an eGFR below 15 as kidney failure (G5), and recommends referral to a kidney specialist when eGFR is below 30. A sudden drop from your usual level also needs prompt review, and KDIGO treats a change of more than 20 percent between tests as larger than normal test-to-test variation, even when the number is still above 60.

Does a low eGFR mean kidney disease if I am older?

Not always. The National Kidney Foundation notes that eGFR normally declines with age and that a low eGFR in an older person does not always mean CKD, even below 60. KDIGO adds that the decline varies a lot between people. Urine albumin and a cystatin C based eGFR help show whether a low result reflects kidney damage.