Difference Between Ccr Cin and Cpah

The key difference between Ccr Cin and Cpah is their function. Ccr is the ability of a person’s kidneys to clear creatinine in the blood plasma. Meanwhile, Cin refers to the ability of kidneys to clear inulin in blood plasma through nephrons. But, Cpah refers to the ability of kidneys to clear para-aminohippurate in blood plasma.

Glomeruli are networks of small blood capillaries seen in nephrons. They are tiny ball-shaped structures involved in the formation of urine. They work as microscopic filters that remove waste products from our blood and clean the blood. Kidney diseases affect the filtration ability of glomeruli. The filtering capacity of the glomeruli can be measured by three parameters: creatinine clearance (Ccr), inulin clearance (Cin) and clearance of para-aminohippurate (Cpah). These are measures of renal clearance or the rate of clearance by the blood plasma.

1. Overview and Key Difference
2. What is Ccr
3. What is Cin
4. What is Cpah
5. Similarities Between Ccr Cin and Cpah
6. Side by Side Comparison – Ccr vs Cin vs Cpah in Tabular Form
7. Summary

What is Ccr?

Creatinine is a waste product produced continuously from the breakdown (normal wear and tear) of muscle tissue. It comes into the bloodstream. Everyone has creatinine in their blood. Our kidney filters and excretes creatinine from our blood in the form of urine. Therefore, the clearance of creatinine in glomeruli is an important function. Creatinine clearance can be defined as the amount of blood the kidney can make free from creatinine per minute. It can be measured by collecting urine for 24 hours or by a blood test.

In a healthy woman, Ccr is about 95 millilitres per minute while it is about 120 millilitres per minute for healthy men. Generally, a person’s kidneys clear 95-120 mL of blood free of creatinine each minute.

Figure 01: Creatinine

Low creatinine clearance indicates kidney damage. The higher or low levels of creatinine clearance sign problems in the kidney, mainly in glomerular filtration. Therefore, Ccr is a good measure of renal function. It is used as a common procedure in testing renal function. However, Ccr can vary depending on the age, sex and size.

What is Cin?

Inulin clearance (Cin) refers to the filtering capacity of the glomeruli to clear inulin (a carbohydrate) from blood plasma. Therefore, kidney function can be determined by measuring the rate of inulin clearance. Inulin is one of the most suitable test substances of kidney function. It readily filters into the tubular filtrate and does not get reabsorbed into the blood. Thus, the amount of inulin cleared through urine is indicative of the amount of plasma filtered by the body’s glomeruli.

Figure 02: Inulin

Generally, the rate of inulin clearance from the blood plasma is about 75–115 ml per minute for women and 85–125 ml per minute for men. Inulin can be measured in urine as well as in serum. The rate decreases with age and conditions such as acute glomerulonephritis (inflammation of the small blood vessels that loop through the glomeruli).

What is Cpah?

Para-aminohippuric acid clearance (Cpah) is another measure that is important in evaluating effective renal plasma flow. Most of the blood that enters the kidney is cleared from para-aminohippuric acid (PAH).

Figure 03: Para-aminohippuric Acid

In fact, PAH is partially filtered form plasma in glomeruli, and the rest is secreted by the peritubular capillaries. But, PAH is never reabsorbed by the tubules. Therefore, renal venous blood contains very little PAH. The amount of PAH in urine depicts the functional capacity and effective renal plasma flow.

What are the Similarities Between Ccr Cin and Cpah?

Ccr, Cin and Cpah are tests that determine the renal function.
They are important in determining the glomerular filtration

What is the Difference Between Ccr Cin and Cpah?

Ccr is the ability of kidneys to filter-out creatinine in blood plasma. Cin is the ability of kidneys to clear inulin in blood plasma, while Cpah is the ability of kidneys to clear PAH in blood plasma. So, this is the key difference between Ccr Cin and Cpah. Besides, creatinine is filtered and secreted, inulin is completely filtered, but PAH is partially filtered and secreted.

Moreover, a person’s kidneys clear 95-120 mL of blood free of creatinine in each minute while the renal clearance of inulin is about 75–115 ml per minute for women and 85–125 ml per minute for men and the renal extraction ratio of PAH in a normal individual is approximately 0.92. Therefore, this is also an important difference between Ccr Cin and Cpah.

Summary – Ccr Cin vs Cpah

Glomerular filtration rate can be measured by the clearance of various substances such as creatinine, inulin and para-aminohippuric acid, etc. It tells us about the function of the kidney, damages in glomeruli, and how healthy your kidneys are. Creatinine is filtered through the glomeruli and also secreted through peritubular capillaries. Inulin is fully filtered through glomeruli. PAH is partially filtered through glomeruli, and the rest is secreted through peritubular capillaries. Thus, this summarizes the difference between Ccr Cin and Cpah.

Reference:

1. Shahbaz, Hassan. “Creatinine Clearance.” StatPearls [Internet]., U.S. National Library of Medicine, 5 July 2019, Available here.
2. “Inulin Clearance.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 7 Feb. 2019, Available here.
3. “Inulin.” Wikipedia, Wikimedia Foundation, 9 Feb. 2020, Available here.

Image Courtesy:

1. “Creatinine” By Jesse – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Inulin strukturformel” By Florian Fisch – Own work (Public Domain) via Commons Wikimedia
3. “Aminohippuric acid” By Edgar181 – Own work (Public Domain) via Commons Wikimedia