Low glomerular filtration rates (GFR) are caused by chronic kidney diseases according to MedicinePlus. The GFR is a measure of the amount of blood that passes through the glomeruli, which are tiny filters in the kidneys responsible for removing waste, in a single minute. To determine the GFR, blood tests are required.
A normal GFR ranges anywhere from 90 to 120 milliliters per minute; however, the numbers will vary slightly depending on the age of the patient, along with the laboratory that handles the testing. A GFR that has dropped below 60 milliliters per minute is considered to be low. Older patients tend to have a lower GFR.
Although the GFR can be used to determine whether a patient has chronic kidney disease, chronic kidney disease can also be a sign that the patient has diabetes, heart disease, high blood pressure, a urinary blockage and frequent urinary tract infections.
To prepare for the blood testing and to ensure that the results are accurate, most medical professionals would recommend refraining from taking medications like antibiotics and stomach acid medications. Before the test, it is important to discuss with a doctor all of the medications that one may be taking in order to determine whether any of the medications may be a problem.