GFR is calculated as:
**Core Concept**
Glomerular filtration rate (GFR) is a critical measure of kidney function, representing the volume of fluid filtered from the renal glomeruli per unit time. It is an essential parameter in assessing the overall renal health and function.
**Why the Correct Answer is Right**
The correct formula for calculating GFR is the Cockcroft-Gault equation, which takes into account the patient's age, sex, weight, and serum creatinine levels to estimate the GFR. This equation is widely used in clinical practice to assess kidney function and monitor the progression of kidney disease. The formula involves the following variables: serum creatinine, age, weight, sex, and a constant factor.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not take into account the patient's age, sex, or weight, which are essential factors in estimating GFR.
**Option B:** This option is incorrect as it only includes serum creatinine and does not account for other important variables such as age, sex, and weight.
**Option C:** This option is incorrect as it is a simplified version of the Cockcroft-Gault equation and does not accurately reflect the complex relationship between GFR and the variables involved.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that the Cockcroft-Gault equation is a widely accepted and validated method for estimating GFR, but it may not accurately reflect GFR in patients with certain comorbidities, such as obesity or liver disease.
**Correct Answer: C. GFR = (140 - age) * weight (kg) / (72 * serum creatinine (mg/dL)) for men, or (140 - age) * weight (kg) / (72 * serum creatinine (mg/dL)) * 0.85 for women.