Difference Between Creatinine Clearance and GFR

The key difference between Creatinine Clearance and GFR relies on the type of test that helps analyze each measurement. Creatinine clearance analysis takes place via urine test whereas GFR analysis takes place via a blood test.

Renal health depends on the efficiency and accuracy of kidney functioning. Therefore, the three main steps of urine formation are vital for renal health. The three main steps are ultrafiltration, selective reabsorption, and tubular secretion. Ultrafiltration takes place in the glomerulus, and both creatinine clearance and GFR relate to the efficiency of the ultrafiltration process.

CONTENTS

1. Overview and Key Difference
2. What is Creatinine Clearance 
3. What is GFR
4. Similarities Between Creatinine Clearance and GFR
5. Side by Side Comparison – Creatinine Clearance vs GFR in Tabular Form
6. Summary

What is Creatinine Clearance?

Creatinine is a waste product that results from the normal breakdown process of muscle tissue. Ultrafiltration filters creatinine into the urine during urine production in kidneys and there is no reabsorption of creatinine into the bloodstream. Creatinine clearance is the amount of blood filtered by kidneys in each minute in order to make blood free of creatinine. In a healthy woman, the creatinine clearance is about 95 mL per minute. In a healthy man, the creatinine clearance is 120 mL per minute. Therefore, our kidneys make 95-120 ml of blood free from creatinine per minute.

The main function of the creatinine clearance test is to predict renal function. Thus, creatinine clearance levels show the kidney’s ability to filter the blood and the efficiency of the ultrafiltration process in urine formation. A simple urine test reveals the creatinine clearance. To carry out this test, the urine of a person should be collected for the past 24 hours. Then, it is possible to estimate the level of creatinine present in the urine sample. Since it is necessary to collect urine for 24 hours, the test can be a bit inconvenient. But, it is an important test to diagnose some kidney conditions.

What is GFR?

Glomerular Filtration Rate (GFR) is the rate at which blood passes through the glomerulus during ultrafiltration. During glomerular filtration, all blood constituents except blood cells are filtered into the tubular network of the nephron via the Bowman’s capsule. The filtration takes place according to a pressure gradient. The glomerular filtration takes place in nephron during urine formation. Thus, the glomerular filtration test determines the functionality of the kidney.

GFR test is done via blood sample analysis. The blood creatinine levels determine the glomerular filtration rate. In addition to blood creatinine levels, parameters such as age, ethnicity, gender, height and weight affect the glomerular filtration rate.

What are the Similarities Between Creatinine Clearance and GFR?

• Both creatinine clearance and GFR predict the efficiency of the ultrafiltration process.
• They measure the creatinine levels; however, the source differs.
• Both predict the renal health of an individual.
• Moreover, they depend on factors such as age, gender, weight, etc.

What is the Difference Between Creatinine Clearance and GFR?

Creatinine clearance test and GFR test are two tests to measure the efficiency of the kidneys during its filtration step. However, the sources of the two tests are different; the source of creatinine clearance is a urine sample while the source of GFR is the blood. So, this is the key difference between creatinine clearance and GFR.

The below infographic summarizes the difference between Creatinine Clearance and GFR.

Summary – Creatinine Clearance vs GFR

Creatinine clearance and GFR measure the efficiency of kidneys during ultrafiltration. Creatinine is the marker to measure the efficiency of the kidneys. In this context, creatinine clearance is the amount of blood filtered by kidneys in each minute in order to make blood free of creatinine. In contrast, GFR measures the blood creatinine levels to analyze the glomerular filtration rate. Age and gender play a major role in determining both the measurements. So, this summarizes the difference between creatinine clearance and GFR.

Reference:

1. Simetić, Lucija, et al. “Creatinine Clearance and Estimated Glomerular Filtration Rate–When Are They Interchangeable.” Collegium Antropologicum, U.S. National Library of Medicine, Sept. 2015, Available here.

Image Courtesy:

1. “Creatinine” By Jesse – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Anatomy and physiology of animals Filtration in the glomerulus capsule” By The original uploader was Sunshineconnelly at English Wikibooks. – Transferred from en.wikibooks to Commons by Adrignola using CommonsHelper (CC BY 3.0) via Commons Wikimedia