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How Albumin Maintain Osmotic Pressure

How Albumin Maintain Osmotic Pressure

Plasma, a pale yellowish fluid, constitutes approximately 55% of our blood composition, while the remaining portion consists of solid components. 

Plasma is mostly water, around 90%, and the remaining 10% is a mixture of ions, proteins, gasses, nutrients, and waste materials.

One of these vital proteins in blood plasma is albumin, which plays a crucial role in maintaining serum osmotic pressure. 

Now, let’s delve into what albumin is and why doctors recommend an albumin test. We will also explore how albumin maintains osmotic pressure. 

What Does Albumin Mean? 

In blood plasma, albumin holds the title of being the most abundant protein. Despite being the smallest of all plasma proteins, it constitutes the largest percentage, approximately 60%, in healthy individuals.

The liver synthesizes it and is a crucial carrier for substances like drugs, hormones, and fatty acids.

Albumin ensures the blood’s colloid osmotic pressure stays regulated.

Why is it Crucial to Maintain Osmotic Pressure? 

When the body lacks enough plasma proteins, the water in the plasma can leak into the area around the blood vessels. This can result in interstitial oedema, commonly seen in individuals suffering from liver disorders, kidney disease, or malnutrition. 

Therefore, it is crucial to maintain the colloid osmotic pressure of the blood to achieve a balance between the water inside the blood and the fluid in the tissue surrounding the cells.

 Albumin plays a vital role in preventing fluid leakage from the bloodstream.

Why is the Albumin Test Done? 

An albumin test is a blood test used to measure the albumin levels in blood. A healthcare provider can recommend albumin blood tests if he suspects liver or kidney dysfunction. 

The test is included in a routine screening called a Comprehensive Metabolic Panel (CMP), which checks sugar levels and digestive health.

Normal Range for Albumin Levels

While low albumin levels may be signs of severe liver or kidney disease, high albumin levels (hyperalbuminemia) can indicate dehydration, diarrhea or other health conditions. 

A typical range for albumin levels in the blood is between 3.4 to 5.4 g/dL or 34 to 54 g/L.

The Role of Albumin in Maintaining Osmotic Pressure 

Osmosis is a process in which water moves from a high to a low concentration area through a semipermeable membrane, balancing the water on both sides. 

Albumin constitutes roughly 60% of the blood plasma proteins, resulting in reduced water content in the blood. This creates a concentration gradient between blood and fluid in surrounding tissues. 

As a result, these specialized proteins attract water towards a specific area to balance the water content between the blood and the fluid surrounding the cells.

Albumin’s osmotic effect is mainly due to its large molecular weight and partially its negative charge. 

The negative charge of albumin attracts positively charged molecules and, consequently, water in the intravascular compartment. 


In conclusion, albumin is one of the most abundant proteins in blood plasma. It helps regulate the osmotic pressure of blood by preventing fluid leakage from the blood vessels into the surrounding tissues. 

The albumin test determines albumin levels in the blood, which helps diagnose or rule out liver or kidney dysfunction. 

You can conveniently book an appointment at Grace Laboratory to schedule a blood test.


1. What does excess albumin in urine indicate? 

An excess of albumin in the urine may indicate albuminuria, a sign of kidney disease. If your kidney is damaged, some albumin will pass into the urine. This can be early signs of conditions like diabetes and high blood pressure. 

2.  What is osmotic pressure? 

Osmotic pressure arises from solutes in a solution, attracting water like a “pulling” force. In capillaries, albumin proteins primarily generate osmotic pressure, drawing water towards the bloodstream.

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