Serum Proteins Total

Sample for Serum Protein

1. This is done on the serum of the patient.
2. Analyze a fresh sample or store it at 4 °C for >72 hours.
3. For 6 months, stored at -20 °C.

Precautions for Serum Proteins

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. 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.

Indications for Serum Proteins

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

Types of Serum Proteins

1. Human bodies contain thousands of proteins. These are present in the intracellular and extracellular spaces.
2. These are present in the blood, urine, CSF, amniotic fluid, saliva, feces, and peritoneal and pleural fluids.
3. 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 little or no water space in the molecule’s interior.
      2. Most globular proteins retain their biological activities within the narrow range of pH and temperature.
      3. If these are exposed to a high temperature, their molecule is denatured.
   3. Conjugated proteins examples are lipoproteins, glycoproteins, mucoproteins, metalloproteins, mucoproteins, and phosphoproteins.

Properties of serum proteins:

1. Molecular size influences the property of the various proteins. The 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 solvents’ pH, temperature, ionic strength, and dielectric constant.
4. Specific binding to the antibodies, hormone receptor, and coenzymes. This is their unique property, and these proteins can bind to specific antibodies, which is 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.

Various types of proteins:

1. Total serum proteins consist of:
   1. Prealbumin.
   2. Albumin.
   3. Globulins.
2. Other proteins included are:
   1. Complements.
   2. Fibrinogen.
   3. C – Reactive protein.
3. Miscellaneous proteins are :
   1. Myoglobin.
   2. Troponin.
   3. Fibronectin.
   4. Amyloid.
4. Proteins found in other body fluids are :
   1. Urinary protein.
   2. Cerebrospinal fluid protein.
   3. Protein in the ascetic and pleural fluid.

Functions of proteins:

1. Their main function is maintaining the osmotic pressure, which keeps the fluid within vascular spaces.
2. Albumin is made in the liver, and it is 60% of the total proteins.
   1. Albumin’s 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 measures liver function.
   4. The half-life of albumin is 12 to 18 days. So liver damage will not be seen during this period.
3. Proteins act as carrier proteins, and some of these are:
   1. Haptoglobin.
   2. Prealbumin.
   3. Transferrin.
4. Proteins demonstrate various biological functions:
   1. Enzymes catalyze the biochemical reaction, which is essential for metabolism.
   2. Proteins, polypeptides, and oligopeptide hormones regulate metabolism.
   3. Antibody proteins and the complement system protect against infection.
   4. Proteins maintain the osmotic pressure of the plasma.
   5. Hemoglobin carries oxygen.
   6. Protein coagulation factors take part in hemostasis.
   7. They transport hormones, vitamins, metals, and drugs.
5. 8. Proteins act as carrier proteins for transporting various other proteins, hormones,  and drugs. These are separated on the electrophoresis.

Proteins and their functions

Albumin as a carrier protein:

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

Prealbumin as a carrier protein:

• Transport protein for T3 and T4, steroid hormones, and Vit. A.

NORMAL  Serum proteins

Source 1

• To convert into SI unit x 10 = g/L

Source 4

• Total proteins
• Adult = 6 to 8.0 g/dL.
• Child newborn = 4.6 to 7.4 g/dL.
  • Child 1 to 3 years = 5.9 to 7.0 g/dL.
  • Child 4 to 6 years = 5.9 to 7.8 g/dL.
• Albumin
  • Adult = 3.5 to 5 g/dL.
  • Premature infant = 3 to 4.2 g/dL
    • Newborn   = 3.5 to 5.4 g/dL
    • Infants = 4.4 to 5.4 g/dL
    • Child = 4 to 5.9 g/dL

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:

• This may be due to dehydration

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.

Questions and answers:

• Please see more details in Protein serum Electrophoresis.