Plasma Proteins ● Plasma is the liquid portion of blood and constitutes 55% of total blood volume. ● Plasma consists of: 90% Water 8% Proteins 0.9% Inorganic ions 1.1% Organic substances ● Origin: Liver except for immunoglobulins which are synthesized in the lymphoid tissue.

Classification of plasma proteins 1. Albumin (60% of total plasma proteins) 2. Globulins (36% of total plasma proteins): i. α 1 globulins ii. α 2 globulins iii. β-globulins iv. γ- globulins

Function of protein fractions 1. Albumin (ALB) ● represents 60% of total plasma proteins. ● Func.: a. maintains the colloid osmotic pressure of blood. b. binds to and transports billirubin, calcium and drugs.

2. Globulins: ● represents 36% of total plasma proteins. i. α 1 globulins as α-fetoprotein ii. α 2 globulins as α 2 -macroglobulins iii. β globulins as fibrinogen. iv. γ globulins as immunoglobulins including IgA, IgM, IgG. Function of protein fractions

Normal range and variation Used to evaluate nutritional status, and to screen for liver disease or kidney disease. Sample? Venous Blood Sample. When ordered? Patient experiences unexpected weight loss or has symptoms of liver or kidney disorders. 1. Total Proteins: ● Normal level 6-8 g/dL ● If abnormal, further measurements are required.

2. Albumin (ALB): ● Normal range  3-5 g/dL ● Increased level suggests Dehydration ● Decreased level indicates: 1. Fluid retention 2. Decreased synthesis due to: a. Malnutrition or malabsorption of dietary peptides and amino acids. b. Impaired synthesis due to chronic liver dysfunction. Why? Normal range and variation

2. Albumin (cont.): ● Decreased level indicates: 3.Increased protein catabolism as in diabetes mellitus and hyperthyroidism. 4. Increased loss from the body through: a. skin in case of burns. b. intestinal wall as in protein-losing enteropathy. c. glomeruli as in nephrotic syndrome NB: Albumin levels decrease normally in pregnancy.

3. A/G ratio: ● calculated from values obtained by measurement of total proteins & albumin. ● Normal A/G ratio is over 1. A high A/G ratio suggests: underproduction of immunoglobulins as in leukemias. A low A/G ratio may reflect: a. hypoalbuminemia. b. overproduction of globulins (as in multiple myloma or autoimmune diseases) Normal range and variation

4. Globulins: Normal level  g/dL Low levels suggests underproduction of globulins (genetic deficiencies and in some leukemias). High levels indicates overproduction of globulins (such as seen in multiple myeloma or autoimmune diseases). Normal range and variation

Practical Session

Determination of Total Proteins PRINCIPLE: Peptide group of proteins form a violet complex with Cu 2+ ions in alkaline medium ( Biuret reagent). The purple complex is measured at 550 nm

Determination of Total Proteins PROCEDURE: 0.1 ml Plasma Sample + 1 ml Biuret reagent Wait for 10 min Violet complex (Measured at 550 nm)

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