Plasma Proteins ● Plasma is the liquid portion of blood and constitutes 55% of total blood volume....

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Transcript of Plasma Proteins ● Plasma is the liquid portion of blood and constitutes 55% of total blood volume....

Plasma Proteins● Plasma is the liquid portion of blood and

constitutes 55% of total blood volume. ● Plasma consists of:

90% Water8% Proteins0.9% Inorganic ions1.1% Organic substances

● Origin: Liver except for immunoglobulins which are synthesized in the lymphoid tissue.

Classification of plasma proteins1. Albumin (60% of total plasma proteins)2. Globulins (36% of total plasma proteins): i. α1 globulins

ii. α2 globulins

iii. β-globulinsiv. 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. α1 globulins as α-fetoprotein

ii. α2 globulins as α2-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 retention2. 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.

Normal range and variation

3. A/G ratio:● calculated from values obtained by

measurementof 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 2-3.8 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 Cu2+ 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)

Thank you