Serum Proteins, Body Total Proteins
Serum Proteins Total
Sample for Serum Protein
- This is done on the serum of the patient.
- Analyze a fresh sample or store it at 4 °C for >72 hours.
- For 6 months, stored at -20 °C.
Precautions for Serum Proteins
- Avoid prolonged application of a tourniquet. This will lead to hemoconcentration and give a false rise in values.
- Avoid hemolysis and lipemic serum.
- Avoid blood from the side of the I/V infusion, which will lower the result.
- Drugs like anabolic steroids, androgens, dextran, growth hormone, progesterone, and insulin increase the protein level.
- Some of the drugs decrease the level, like estrogen, hepatotoxic drugs, and oral contraceptives.
Indications for Serum Proteins
- This is the best marker for liver function activity.
- This test will assess renal function.
- Assess the protein-losing diseases of the intestines and kidneys.
- Assess the immune disorder.
- Assess impaired nutrition.
- To evaluate the chronic edematous conditions.
- To evaluate patients with malignancies like lymphoma and myeloma.
Types of Serum Proteins
- Human bodies contain thousands of proteins. These are present in the intracellular and extracellular spaces.
- These are present in the blood, urine, CSF, amniotic fluid, saliva, feces, and peritoneal and pleural fluids.
- Proteins are divided into:
- Fibrous, e.g., fibrinogen, troponin, collagen, and myosin.
- Globular, e.g., hemoglobin, enzymes, peptide hormones, and plasma proteins.
- Globular proteins are compact and have little or no water space in the molecule’s interior.
- Most globular proteins retain their biological activities within the narrow range of pH and temperature.
- If these are exposed to a high temperature, their molecule is denatured.
- Conjugated proteins examples are lipoproteins, glycoproteins, mucoproteins, metalloproteins, mucoproteins, and phosphoproteins.
Properties of serum proteins:
- Molecular size influences the property of the various proteins. The smaller molecule can be separated by dialysis, ultrafiltration, chromatography, and density gradient ultracentrifugation.
- Electrical charges of the proteins lead to their mobility in the electrical field. These proteins are separated by electrophoresis.
- The difference in the solubility of the proteins depends upon the solvents’ pH, temperature, ionic strength, and dielectric constant.
- 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.
- Proteins are the source of nutrition and a buffer system.
- Proteins are part of muscles, hormones, enzymes, hemoglobin, and transport protein.
Various types of proteins:
- Total serum proteins consist of:
- Other proteins included are:
- C – Reactive protein.
- Miscellaneous proteins are :
- Proteins found in other body fluids are :
- Urinary protein.
- Cerebrospinal fluid protein.
- Protein in the ascetic and pleural fluid.
Functions of proteins:
- Their main function is maintaining the osmotic pressure, which keeps the fluid within vascular spaces.
- Albumin is made in the liver, and it is 60% of the total proteins.
- Albumin’s main function is to maintain the colloid osmotic pressure.
- Albumin acts as a transport protein for drugs, hormones, and enzymes.
- Albumin is synthesized in the liver, so it measures liver function.
- The half-life of albumin is 12 to 18 days. So liver damage will not be seen during this period.
- Proteins act as carrier proteins, and some of these are:
- Proteins demonstrate various biological functions:
- Enzymes catalyze the biochemical reaction, which is essential for metabolism.
- Proteins, polypeptides, and oligopeptide hormones regulate metabolism.
- Antibody proteins and the complement system protect against infection.
- Proteins maintain the osmotic pressure of the plasma.
- Hemoglobin carries oxygen.
- Protein coagulation factors take part in hemostasis.
- They transport hormones, vitamins, metals, and drugs.
- 8. Proteins act as carrier proteins for transporting various other proteins, hormones, and drugs. These are separated on the electrophoresis.
Proteins and their functions
|Type of protein||Quantity||Site of formation||Functions|
|Albumin||60%||Liver||Maintain blood osmotic pressure|
|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 as a carrier protein:
- Transport protein.
- Maintain osmotic pressure.
- Source of endogenous amino acid.
Prealbumin as a carrier protein:
- Transport protein for T3 and T4, steroid hormones, and Vit. A.
NORMAL Serum proteins
|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|
|Ambulatory||6.4 to 8.3|
|Recumbent:||6.0 to 7.8|
|>60 years||Lower by ∼0.2|
|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|
- To convert into SI unit x 10 = g/L
- 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.
- 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:
- Monoclonal gammopathy
- polyclonal gammopathy
Causes of Hypoproteinemia:
- Decrease protein synthesis like liver diseases and decreased amino acid intake
- Increased protein loss like nephrotic syndrome
- Increased protein catabolism, like in malignancies and inflammation
Causes of Hyperalbuminemia:
- This may be due to dehydration
Causes of hypoalbuminemia:
- Decreased albumin synthesis seen in liver diseases and decreased amino acid intake
- Increased albumin loss is seen in kidney diseases like nephrotic syndrome, blood loss, and burns
- Increased catabolism of albumin seen in malignancy and inflammation.
Questions and answers:
Question 1: What is the role of prealbumin?
Prealbumin acts as a carrier protein for thyroxine, steroid hormones, and vitamin A.
Question 2: What are the types of proteins?
Proteins may be fibrous, globular, and conjugated proteins.
- Please see more details in Protein serum Electrophoresis.