Bioquímica Clínica 04/02

Summary

This presentation explains laboratory diagnostic criteria for hypoproteinemia and hyperproteinemia, focusing on the two main protein groups: albumin and globulins. It covers their functions in the body, including transport, immune response, and blood clotting, and emphasizes the importance of these proteins in diagnosing metabolic disorders. The presentation also details common laboratory methods used to measure protein levels, such as colorimetric assays, and discusses the significance of albumin-to-globulin ratios. Additionally, it highlights sample preparation requirements and potential interferences in testing, providing a comprehensive overview of protein analysis in clinical diagnostics.

Takeaways

• 😀 Hypoproteinemia and hyperproteinemia refer to low and high levels of protein in the blood, respectively, and are key in diagnosing metabolic disorders.
• 😀 Proteins are made up of amino acids linked by peptide bonds, and they play vital roles in functions like transport, immunity, and enzyme activity.
• 😀 Albumin is the most abundant serum protein, making up 55-65% of total proteins, and is critical in regulating osmotic pressure and transporting substances.
• 😀 Albumin production depends on dietary amino acids, and its half-life is around three weeks in healthy adults.
• 😀 Globulins are classified into alpha, beta, and gamma fractions, each containing specific proteins with functions like immune defense and transport.
• 😀 Techniques like electrophoresis help classify globulins and identify which fraction (alpha, beta, or gamma) predominates in a blood sample.
• 😀 The alpha-1 fraction includes proteins like alpha-1 antitrypsin, while alpha-2 contains haptoglobulin and alpha-2 macroglobulin.
• 😀 The beta fraction includes transferrin and lipoproteins, while the gamma fraction is made up of immunoglobulins and C-reactive protein (CRP).
• 😀 Serum proteins are crucial for maintaining osmotic pressure, catalyzing biochemical reactions, defending against pathogens, and supporting coagulation.
• 😀 Sample handling is important for accurate testing: serum should be free from hemolysis and lipemia, and fasting is not required for protein testing.

Q & A

What are the main criteria for diagnosing hypoalbuminemia and hyperproteinemia in the blood?

The diagnosis of hypoalbuminemia (low protein levels) and hyperproteinemia (high protein levels) is based on laboratory tests that measure the concentration of proteins in the blood, particularly albumin and globulins. These proteins are essential for various bodily functions and can indicate underlying metabolic disorders.

What are the main functions of proteins in the human body?

Proteins play many crucial roles in the body, such as transporting and storing substances, catalyzing chemical reactions (enzymes), providing structural support, aiding in muscle contraction, defending against pathogens, and contributing to blood clotting.

How are albumin and globulin different in terms of their composition and function?

Albumin is the most abundant protein in the blood, responsible for maintaining osmotic pressure and transporting various substances like medications and fats. Globulins, on the other hand, are a group of proteins divided into fractions (alpha, beta, and gamma) and are involved in immune responses, enzyme activities, and transport of metals like iron.

How is albumin produced in the body?

Albumin is produced mainly in the liver, and its synthesis depends on dietary intake of amino acids. It has a half-life of about three weeks in a healthy adult, meaning it is broken down and eliminated from the body approximately every three weeks.

What methods are used to measure albumin and globulins in the laboratory?

Albumin and globulins are typically measured using colorimetric methods, where chemical reactions produce a color change that is proportional to the protein concentration. Specific reagents, such as bromocresol green for albumin, are used to create these reactions.

What is the role of albumin in regulating osmotic pressure?

Albumin helps maintain the balance of water distribution between the intracellular and extracellular spaces by regulating osmotic pressure. It is responsible for 75-80% of this regulation in the body. Low albumin levels can disrupt this balance and cause fluid retention or edema.

What is the significance of globulins and their fractions in protein analysis?

Globulins are categorized into fractions (alpha, beta, and gamma) based on their behavior in electrophoresis. Each fraction contains proteins with distinct roles, such as immune response (immunoglobulins in gamma), metal transport (transferrin in beta), and enzymatic activity (alpha 1-antitrypsin in alpha). These fractions provide insights into various metabolic and immune conditions.

What factors can interfere with protein measurements in the laboratory?

Several substances and medications can interfere with protein measurements, leading to falsely high or low results. For example, corticosteroids, heparin, and certain contrast agents can elevate protein levels, while contraceptives and salicylates may cause false reductions.

What is the recommended sample for measuring serum protein levels?

The recommended sample for serum protein measurements is blood serum, which should be free from hemolysis (ruptured red blood cells) and lipemia (excess fat). The serum should be stored refrigerated for up to one week to ensure accurate results.

How can you interpret the results of protein measurements in terms of health conditions?

Abnormal levels of albumin or globulin can indicate various health issues. Low albumin may suggest liver disease, malnutrition, or kidney problems, while high globulin levels may be a sign of inflammation, infections, or immune system disorders. Proper interpretation requires understanding the context and associated clinical symptoms.