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A normal glomerular filtration rate (GFR) is >90 mL/min/1.73 m2.
In the body, the kidneys help filter the blood and turn the waste products into urine. This happens by blood flowing through little clusters of blood vessels, called glomeruli, that sit adjacent to the kidney tubules. The GFR is a measure of the amount of blood that gets filtered through the kidneys in a given amount of time. A decreased GFR is a sign of kidney disease, and a GFR <15 mL/min/1.73 m2 is considered end-stage chronic kidney disease. The GFR can sometimes be increased by addressing the underlying cause of kidney disease. However, if the kidneys have failed, dialysis or kidney transplant is necessary.
What we mean by normal
In medicine, using the term “normal” can sometimes be off-putting. Saying something is “normal” implies that everything else is “abnormal.” Additionally, saying something is “normal” may not be accurate, since something that is “normal” for you may not be “normal” for somebody else. Therefore, instead of saying certain values are “normal,” alternative terminology may be to say that these values are “healthy” or “within the reference range.”
Additionally, some values have well-defined cutoffs, while others do not. For example, when looking at hemoglobin A1c levels, a value of 6.5 or greater is always diagnostic of diabetes. On the other hand, when looking at testosterone levels, some use cutoffs of 270–1,070 ng/dL while others use cutoffs of 300–1,000 ng/dL.
The information above represents values that are commonly used as cutoffs. However, depending on the specific source you’re looking at or the laboratory you go to, their values may be a little different.
Dr. Tzvi Doron is Board Certified in Family Medicine by the American Board of Family Medicine and is Ro's Chief Clinical Officer.