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The estimated glomerular filtration rate (eGFR) measures how well the kidneys filter waste from the blood. It helps assess kidney function, with normal eGFR levels being above 90 mL/min/1.73 m². Lower values may indicate kidney disease, with eGFR decreasing as kidney function worsens. When kidney function is not optimal, serious health problems can occur. With Homed-IQ, it is possible to perform a liver and kidney function test from home. This test measures key liver and kidney biomarkers, including the eGFR value- an important indicator of kidney function. Homed-IQ also offers a Kidney Damage Test that measures the albumin/creatinine ratio.
What is eGFR?
eGFR stands for estimated glomerular filtration rate. This value is an estimate that can be determined based on the blood creatinine levels. Creatinine is a product produced when energy is broken down in the muscles. The kidneys constantly filter this product from the blood, after which it leaves the body via urine. When the kidneys are functioning normally, the amount of creatinine in the blood is low. However, if the kidneys are not functioning properly, creatinine can remain in the blood and build up. The outcome of an eGFR test estimates the amount of blood that the kidneys filter per minute, and is an indicator of how well the kidneys function.
The value of the filtration rate differs from person to person. For example, in a healthy individual, the result of an eGFR test is more than 90 milliliters per minute. However, the speed decreases as you get older. People with an advanced age therefore usually have a lower eGFR (an average of 30 to 45 milliliters per minute). This is not seen as an abnormal value due to age.
What is a good eGFR value?
A good eGFR value indicates that the kidneys are filtering the blood optimally. A good eGFR value is defined as more than 90 milliliters per minute.
Which eGFR value is critical?
A GFR value below 60 mL/min/1.73 m² is considered critical, as it may indicate chronic kidney disease. A lower eGFR value corresponds to different stages of kidney disease severity (Netherlands General Practitioners Association, 2019):
| Stage of Kidney Insufficiency | GFR Value (mL/min/1.73 m²) | Interpretation |
| 1 | Over 90 | Normal kidney function |
| 2 | 60–89 | Mild kidney damage |
| 3 | 30–59 | Moderate kidney damage |
| 4 | 15–29 | Severe kidney damage |
| 5 | Below 15 | Kidney failure (dialysis or transplant required) |
eGFR Testing
Testing your eGFR with Homed-IQ provides insight into the filtration rate of the kidneys. This biomarker is part of the Liver and Kidney Function Test. This home test consists of a urine test and a finger prick for blood collection, after which a certified laboratory carries out the analysis. In addition to the eGFR value, this test provides insight into a number of other biomarkers, such as ALT, AST, GammaGT, Bilirubin, Albumin, Creatinine, eGFR, and Alkaline Phosphatase. With this, the test offers several parameters to determine your kidney and liver function. In the initial stages of kidney or liver disease, symptoms are not always noticeable. Therefore, testing can offer early detection.
The causes of an eGFR value that is too low
There are various causes of an eGFR value that is too low. One reason can be natural causes, because with age it is normal for kidney function to decline. Black people also naturally have a lower eGFR. However, it is also possible that you have kidney disease, or a disease involving the kidneys. In most situations, a low eGFR value is due to another cause, such as high blood pressure, heart failure, diabetes or arteriosclerosis. If you receive a test result that your eGFR value is too low, visit your GP to make a formal diagnosis and explore potential causes.
Are there any diseases related to eGFR?
There are various disorders and diseases that are associated with an eGFR that is too low. Impaired kidney function, for example, can be caused by glomerulonephritis. However, this is a rare disease. More often, it is the case that high blood pressure, heart failure, arteriosclerosis, or diabetes are the cause of low eGFR.
What does a low eGFR value mean?
An eGFR value that is too low can mean that the kidneys no longer function optimally, so that the blood is not properly purified. This gives waste products the opportunity to accumulate in the body. Kidneys that no longer function optimally are often unable to properly regulate the fluid balance in the body (Albert Schweitzer Hospital). Furthermore, reduced kidney function can cause problems with bone health. That’s because the kidneys are less able to make vitamin D, which makes bones weaker and possibly more likely to break. People with a lowered eGFR have a higher risk of chronic kidney disease (CKD) progressing to kidney failure. The earlier that kidney disease is found, the greater the chance of slowing or stopping it from getting worse.
Symptoms of an eGFR value that is too low
The symptoms of an eGFR value that is too low are not always immediately noticeable. During mild stages when the value is only slightly lowered, there are sometimes no symptoms at all. When low eGFR ha progressed to moderate or severe renal failure, the following symptoms may occur:
- Itchiness
- Nausea
- Feeling unwell
- Fluid retention
- Swollen ankles
- Urinating either too much or too little
- Shortness of breath
- Bone weakness
- High blood pressure
- Feeling cold
- Fatigue
How can I increase my eGFR?
eGFR can be increased by following a specific diet. It is important to avoid salt as much as possible and to limit protein intake (UMCG). Depending on the level of the kidney function, it may also be necessary to take medication. For example, medicines that lower blood pressure or a vitamin D supplement. If eGFR is severely low, medication to support the filtration function of the kidneys in the removal of waste may also be prescribed. More severe kidney failure may require dialysis or a kidney transplant.
What is the difference between eGFR and creatinine?
Creatinine is a waste product produced in the muscles. The kidneys filter this waste product from the blood and remove it as part of our urine. While creatinine is a waste product, eGFR is a value calculated from creatinine levels that indicates the kidneys’ filtration rate.
