Estimated Glomerular Filtration rate test is a serum-based creatinine test in the form of a blood test for the detection of kidney damage or chronic kidney disease (CKD). It is used to screen for any early kidney damage and to monitor kidney status for patients already suffering from kidney diseases. People suffering from prolonged diabetes and high blood pressure (Hypertension) are prone to kidney damage. Signs of kidney disease include swelling and puffiness of eyes, arms, legs, the problem in urination, loss of appetite, fatigue, nausea, muscle cramps and darkening of the skin. The test is usually periodically ordered to a person suffering from high diabetes or hypertension that is associated with kidney damage in a long run.