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Sample

Precautions

  1. Avoid prolonged application of a tourniquet. This will lead to hemoconcentration and give a false rise in values.  
  2. Avoid hemolysis and lipemic serum.
  3. Avoid blood from the side of the I/V infusion which will lower the result.
  4. The drugs like anabolic steroids, androgens, dextran, growth hormone, progesterone, and insulin increase the protein level.
  5. Some of the drugs decrease the level like estrogen, hepatotoxic drugs, and oral contraceptives.

Indication

  1. This is the best marker for the liver function activity.
  2. This test will assess the renal function.
  3. Assess the protein-losing diseases of intestines, and kidneys.
  4. Assess the immune disorder.
  5. Assess impaired nutrition.
  6. To evaluate the chronic edematous conditions.
  7. To evaluate the patients with malignancy like lymphoma and myeloma.

Pathophysiology

  1. The human bodies contain thousands of the proteins. These are present in the intracellular and extracellular space.
    1. These are present in the blood, urine, CSF, amniotic fluid, saliva, feces, peritoneal and pleural fluids.
    2. Proteins are divided into:
      1. Fibrous e.g. fibrinogen, troponin, collagen, and myosin.
      2. Globular e.g. hemoglobin, enzymes, peptide hormones, and plasma proteins.
        1. Globular proteins are compact and have a little or no space for the water in the interior of the molecule.
        2. Most of the globular proteins retain their biological activities within the narrow range of pH and temperature.
        3. If these are exposed to high temperature then their molecule is denatured.
      3. Conjugated proteins examples are lipoproteins, glycoproteins, mucoproteins, metalloproteins, mucoproteins, and phosphoproteins.
  2. Properties of proteins:
    1. Molecular size influence the property of the various proteins like smaller molecule can be separated by dialysis, ultrafiltration, chromatography, and density gradient ultracentrifugation.
    2. Electrical charges of the proteins lead to their mobility in the electrical field. These proteins are separated by electrophoresis.
    3. The difference in the solubility of the proteins depends upon the pH, temperature, ionic strength and dielectric constant of the solvents.
    4. Specific binding to the antibodies, hormone receptor, and coenzymes. This is their unique property and these proteins can bind to specific antibodies and this the basis of the immunochemical assay.
    5. Proteins are the source of nutrition and a buffer system.
    6. Proteins are part of muscles, hormones, enzymes, hemoglobin, and transport protein.
  3. Their main function is to maintain the osmotic pressure which keeps the fluid within vascular spaces.
  4. Total serum proteins consist of:
    1. Prealbumin.
    2. Albumin.
    3. Globulins.
    4. Other proteins included are:
      1. Complements.
      2. Fibrinogen.
      3. C – Reactive protein.
  5. Miscellaneous proteins are :
    1. Myoglobin.
    2. Troponin.
    3. Fibronectin.
    4. Amyloid.
  6. proteins found in other body fluids are :
    1. urinary protein.
    2. Cerebrospinal fluid protein.
    3. Protein in the ascetic and pleural fluid.
  7. Albumin is made in the liver and it is 60% of the total proteins.
    1. Albumin main function is to maintain the colloid osmotic pressure.
    2. Albumin acts as a transport protein for drugs, hormones, and enzymes.
    3. Albumin is synthesized in the liver so it the measure of liver function.
    4. The half-life of albumin is 12 to 18 days. So liver damage will not be seen during this period.
  8. proteins act as carrier proteins and some of these are:
    1. Haptoglobin.
    2. Prealbumin.
    3. Transferrin.
  9. Functions of proteins
    1. Proteins demonstrate various biological functions like:
      1. Enzymes catalyze the biochemical reaction which is essential for the metabolism.
      2. Proteins, polypeptide and oligopeptide hormones regulate metabolism.
      3. Antibody proteins and the complement system protect against the infection.
      4. Proteins maintain the osmotic pressure of the plasma.
      5. Hemoglobin carries the oxygen.
      6. Protein coagulation factors take part in hemostasis.
      7. They transport hormones, vitamins, metals, and drugs.

            8. Proteins act as carrier proteins for the transport of various other proteins, hormone,  and drugs. These are separated on the electrophoresis.

Proteins and their functions

Type of protein Quantity Site of formation Function
Albumin 60% Liver Maintain blood osmotic pressure
Globulins  36%    
Alpha Globulin   Liver Transport lipids, fats, and fat-soluble vitamins.
Beta Globulins   Liver Transport lipids, fats, and fat-soluble vitamins.
Gamma Globulins   Lymphatic system Take part in the immune system
Fibrinogen 4% Liver Take part in blood coagulation

Albumin act as:

  1. Transport protein.
  2. Maintain osmotic pressure.
  3. Source of endogenous amino acid.

Prealbumin acts as :

NORMAL 

Source 1

Total Proteins
Age g/dL
Cord blood 4.8 to 8.0
Premature  3.6 to 6.0
Newborn 4.6 to 7.0
one week  4.4 to 7.6
7 months to one year 5.1 to 7.3
1 to 2 years 5.6 to 7.5
≥ 3 years 6.0 to 8.0
Adult  
Ambulatory  6.4 to 8.3
Recumbent: 6.0 to 7.8
>60 years Lower by ∼0.2
ALBUMIN
0 to 4 days 2.8 to 4.4
4 days to 14 days 3.8 to 5.4
14 to 18 years 3.2 to 4.5
18 to 60 years 3.4 to 4.8
60 to 90 years 3.2 to 4.6
>90 years 2.9 to 4.5

Source 4

Causes of hyperproteinemia:

  1. Dehydration
  2. Monoclonal gammopathy
  3. polyclonal gammopathy

Causes of Hypoproteinemia:

  1. Decrease protein synthesis like liver diseases and decreased amino acid intake
  2. Increased protein loss like nephrotic syndrome
  3. Increased protein catabolism like in malignancies, and inflammation

Causes of Hyperalbuminemia:

Causes of hypoalbuminemia:

  1. Decreased albumin synthesis seen  in liver diseases and decreased amino acid intake
  2. Increased albumin loss is seen in kidney diseases like nephrotic syndrome, blood loss, and burns
  3. Increased catabolism of albumin seen in malignancy and inflammation

Possible References Used

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