eGFR (estimated glomerular filtration rate) is a measurement used to indicate kidney function by assessing how well the kidneys filter blood. The glomeruli of the kidneys are a collection of small, looping blood vessels which are responsible for filtering water and small molecules from the blood into the urine. The term glomerulus comes from the latin for filter and the plural term is glomeruli. There are approximately 1 million glomeruli in the kidney which filter around 170L of blood a day.
The most widely used blood marker for eGFR in the UK is creatinine. Creatinine is derived from the body’s metabolism of skeletal muscle and from dietary meat. It has a stable concentration in the blood and is filtered by the kidneys. Whenever a blood test for serum creatinine measurement is performed, the laboratory will report an estimate of glomerular filtration rate (eGFR) using a prediction calculation. The eGFR calculation uses your measured blood creatinine levels and adjusts the result to factor in your age, gender and ethnicity, all of which influence your risk of kidney disease.
eGFR measurement indicates whether your kidneys are functioning normally for your age, gender and ethnicity and is generally used to detect early kidney damage. It is also used to monitor kidney function in high risk groups such as patients with diabetes, cardiovascular disease, heart problems or high blood pressure. Certain medicines can also increase the risk of kidney damage such as diuretic drugs and some medicines to treat high blood pressure.
A low eGFR value suggests that some kidney damage may have occurred. An eGFR below 60 for three months or more indicates chronic kidney disease. A doctor will want to investigate the cause of your kidney disease and continue to check your kidney function to help plan your treatment. Symptoms of kidney disease may include the following: