What is the glomerular filtration rate (GFR)?
## Core Concept
The glomerular filtration rate (GFR) is a key indicator of kidney function, representing the volume of fluid filtered from the renal (kidney) glomerular capillaries into the Bowman's capsule per unit time. It is a critical measure used to assess the level of kidney function and diagnose kidney disease. The GFR is typically expressed in milliliters per minute (mL/min) or milliliters per minute per 1.73 square meters (mL/min/1.73 m²).
## Why the Correct Answer is Right
The correct answer, , signifies that the GFR is approximately 120 mL/min. This value is considered normal for a healthy adult and is used as a reference point for evaluating kidney function. The GFR is influenced by factors such as blood pressure, blood flow to the kidneys, and the permeability of the glomerular capillaries. It can be estimated using various formulas that take into account serum creatinine levels, age, sex, and body size.
## Why Each Wrong Option is Incorrect
* **Option A:** This option is incorrect because it does not accurately represent the normal GFR value.
* **Option B:** This option is incorrect as it underestimates the normal GFR.
* **Option D:** This option is incorrect because it overestimates the normal GFR value.
## Clinical Pearl / High-Yield Fact
A crucial point to remember is that the GFR can be estimated using the Modification of Diet in Renal Disease (MDRD) formula or the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula, which are commonly used in clinical practice to assess kidney function without requiring direct measurement. These formulas help in diagnosing and staging chronic kidney disease (CKD).
## Correct Answer Line
**Correct Answer: C. 120 mL/min.**