GFR:
GFR, or glomerular filtration rate, is a measure of the function of the kidneys. It represents the volume of blood that is filtered by the kidneys per minute, and it is typically measured in millilitres per minute (mL/min). The normal range for GFR is typically considered to be above 60 mL/min
There are several ways to classify GFR values:
- Normal:
A GFR of 90 mL/min or higher is considered normal.
- Mildly
reduced: A GFR between 60 and 89 mL/min is considered mildly reduced. This
may be a sign of early kidney damage or dysfunction, and regular monitoring
is recommended.
- Moderately
reduced: A GFR between 30 and 59 mL/min is considered moderately reduced.
This may indicate moderate kidney damage, and treatment may be necessary
to prevent further damage.
- Severely
reduced: A GFR below 30 mL/min is considered severely reduced. This
indicates significant kidney damage and may require treatment with
medications or dialysis.
It's important to note that GFR values can be affected by a
variety of factors, including age, sex, body size, and medications. It's also
important to keep in mind that GFR is just one measure of kidney function, and
other tests may be necessary to fully assess kidney health. If you have any
concerns about your GFR or kidney function, it's important to speak with a
healthcare professional.
How to calculate GFR
There are several ways to estimate GFR, or glomerular
filtration rate, which is a measure of the function of the kidneys. The most
accurate method for measuring GFR is a test called inulin clearance, which
involves injecting a substance called inulin into the bloodstream and measuring
the amount of inulin that is cleared from the blood by the kidneys over a
specific period. However, this test is not commonly used because it is
time-consuming and requires specialized equipment.
Instead, GFR is most often estimated using a formula that considers
several factors, including age, sex, race, and serum creatinine levels. The most
used formula for estimating GFR is the Modification of Diet in Renal Disease
(MDRD) equation, which is as follows:
Modification of Diet in Renal Disease (MDRD) equation: GFR (mL/min/1.73 m^2) = 175 x (serum creatinine) ^ (-1.154) x (age)^ (-0.203) x (0.742 if female) x (1.212 if African American)
Cockcroft-Gault equation:GFR (mL/min) = (140 - age) x (weight in kg) x (0.85 if female) / (72 x serum creatinine)
Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation:GFR (mL/min/1.73 m^2) = 141 x min (Scr/κ,1) ^α x max (Scr/κ,1)^−1.209 x 0.993^age x 1.018 if female x 1.159 if African American
In this formula, serum creatinine is a measure of the waste
product creatinine in the blood, and it is expressed in milligrams per decilitre
(mg/dL). Age is expressed in years, and the factor for sex and race should be
included if applicable.
It's important to note that this is just an estimate of GFR,
and it may not be as accurate as other methods. If you have any concerns about your
GFR or kidney function, it's important to speak with a healthcare professional.