Proteine Serice: Albumine și Globuline

Serum Proteins: Albumins and Globulins

• Plasma proteins consist of albumin and globulins.
• Albumin is more abundant but smaller than globulin, which is larger but less abundant.
• Total serum protein is the sum of albumin and globulin.
• Normal albumin concentration is approximately 4 mg/dL, and globulin is approximately 3 mg/dL.
• Serum total proteins are typically 7 mg/dL (4 + 3).

Globulin Types

• Globulins are further classified as alpha-1, alpha-2, beta, and gamma globulins.
• Alpha-1 globulin: A key example is Alpha-1 antitrypsin, important in lung health (emphysema).
• Alpha-2 globulin: Includes angiotensinogen (converted to angiotensin II, affecting blood vessels and aldosterone release), haptoglobin (important in hemolytic anemia), and ceruloplasmin (related to copper metabolism and Wilson's disease).
• Beta globulin: Includes coagulation factors (except calcium) and transferrin (iron transport).
• Gamma globulin: Immunoglobulins (antibodies) like IgG, IgM, IgA, IgE, and IgD.

Serum Protein Electrophoresis (SPE)

• SPE separates proteins based on charge and size, creating a characteristic pattern on a graph.
• The pattern shows albumin, followed by alpha-1, alpha-2, beta, and gamma globulins.
• Abnormal SPE patterns can indicate various conditions (e.g., multiple myeloma).

Low Serum Protein Levels (Hypoproteinemia)

• Causes: Malnutrition, liver disease (e.g., cirrhosis), protein-losing conditions (e.g., burns, nephrotic syndrome, protein-losing enteropathy, malabsorption).

• Consequences: Loss of fluid from vessels, leading to edema (swelling) in various parts of the body (ankles, pre-sacral area, abdomen, pleural or pericardial effusions, pulmonary edema).

Increased Serum Protein Levels (Hyperproteinemia)

• Causes: Dehydration (creates the illusion of higher protein, but underlying cause not discussed), inflammatory conditions (increase globulins).
• Steroid use or androgens, and other hormones may also increase levels.
• Conditions affecting the liver and kidney negatively will decrease protein levels.

Causes of Specific Protein Changes

• Increased albumin: Dehydration.
• Decreased albumin: Malnutrition, liver disease, protein-losing conditions, inflammatory states, increased vascular permeability, overhydration, pregnancy.
• Increased alpha-1 antitrypsin: Inflammatory conditions.
• Decreased alpha-1 antitrypsin: Liver disease, antitrypsin deficiency.
• Increased alpha-2 globulins: Inflammatory conditions.
• Decreased alpha-2 globulins: Liver disease, hemolysis, Wilson's disease.
• Increased beta globulins: Estrogen use, iron deficiency anemia.
• Decreased beta globulins: Liver disease, malnutrition, disseminated intravascular coagulation (DIC), hemophilia (not resulting in significant electrophoresis changes).
• Increased gamma globulins: Infections, cancers (e.g., multiple myeloma, Waldenstrom macroglobulinemia), chronic inflammatory conditions, Hodgkin's disease.
• Decreased gamma globulins: Immunodeficiency disorders (congenital or acquired), immunosuppressant use, chemotherapy, uncontrolled diabetes, severe nephrotic syndrome.

Important Considerations

• Serum protein analysis is crucial in diagnosing various diseases. These levels can help in pre-operative assessments.
• Collection techniques (e.g. prolonged tourniquet use) can produce inaccurate results.

Protein Metabolism

• Protein digestion breaks down proteins into amino acids.
• Amino acids undergo deamination and transamination to form ammonia.
• The liver converts ammonia to urea.
• The kidneys excrete urea in urine.
• Liver disease can lead to hyperammonemia; kidney disease leads to uremia.