Estimation of total protein in serum – liver function tests

Estimation of total protein in serum

Introduction

• Total protein make about 7 % of body weight
• Blood proteins includes albumin , globulins , fibrinogen , regulatory proteins and other types
• Total protein test measures the total amount of two classes of proteins in blood (albumin and globulin)
• Albumin is synthesized by liver using dietary proteins and removed from blood by kidney
• All plasma proteins are synthesized in the liver except Ȣ – globulins , there are different types of globulin called alpha , beta and gamma globulins , Ȣ – globulin made by immune system
• Amino acids are the building block of proteins , in turn proteins are the building block of cells and body tissues

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Principle

• Total protein test depend on Biuret method for determination of protein concentration
• Biuret reagent is made of NaOH , KOH , and CuSO₄ together with Na – K tartarate 
• It is a blue reagent turns to violet in presence of protein in alkaline medium

Normal range

• Total protein : 6.5 – 8 g %

Reagents

• CuSO₄ : color reagent
• NaOH , KOH , Na – K tartarate : alkaline medium (working solution)
• Standard protein

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Procedure

Serum total protein level increased in:

• Dehydration
• Chronic infection or inflammation as virus C , B
• Hemolysis

Serum total protein level decreased in:

• Malnutrition or malabsorption
• Liver disease
• Glomerulonephritis

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Notes

• Total protein = serum albumin + serum globulin
• Serum globulin (g %) = total protein (g %) – serum albumin (g %)

Normal range of globulins: 2.8 – 3.2 g %
Serum globulins level increased in:

• Liver disease
• Infection
• Kidney disease

Serum globulins level decreased in:

• Liver dysfunction (α , β globulins)

Ratio of albumin / globulin > 1

• It must be greater than 1
• Increased in high protein in diet
• Deceased in liver dysfunction