eGFR testing is used when the kidneys are not functioning properly and their function is reduced. eGFR testing is also used to detect kidney disease when there is damage to the glomeruli, which are responsible for filtration in the kidneys. Some symptoms that may indicate the need for this test include:

Fatigue,
Itching,
Swelling in the arms, legs, and feet,
Nausea,
Muscle cramps,
Vomiting,
Loss of appetite,
Frequent urination or less urination than normal.