Introduction à la biochimie clinique

Introduction to Clinical Biochemistry

• Clinical approach involves anamnesis (gathering animal history), physical exam, and complementary tests (e.g., blood and urine analysis) to diagnose, predict prognosis, and prescribe treatment.
• Clinical biochemistry aids in definitive diagnosis, especially in conditions like diabetes (hyperglycemia), kidney disease (urea and creatinine levels), and monitoring treatment efficacy (e.g., phenobarbital levels).

Sources of Error in Biochemical Tests

• Physiological variations: factors like stress increase blood glucose due to adrenaline production.
• Non-physiological errors: incorrect sample handling (e.g., missing NaF in glucose measurement tubes) can influence results.
• Postprandial samples exhibit elevated glucose levels, impeding proper interpretation.
• Other factors, like individual variability and handling procedures, can either elevate or reduce test precision.

Biochemical Analysis Techniques

• Techniques for sample collection are important (e.g., sterile collection for bacterial cultures).
• Analysis can be macroscopical, using visual observations or microscopical observation, or done using specialized equipment.

Biochemical Tubes

• Different tubes are necessary depending on the analysis:
  • Dry tubes are used for chemical tests, including electrophoresis.
  • EDTA tubes are used for hematological analysis.
  • Tubes with oxalate and fluoride are used to prevent blood coagulation and maintain relevant biochemical constituents during analysis.

Glucose Analysis

• Glucose is important for all cell energy.
• Glucose levels are regulated by hormones, such as insulin and glucagon, and stress hormones like adrenaline.
• There are various causes of hypoglycemia and hyperglycemia: fasting, stress, and underlying metabolic conditions (e.g., diabetes mellitus).

Protein Analysis

• Plasma proteins perform diverse functions including blood pressure regulation, transport, and immune response; most are produced in the liver, except immunoglobulins.
• Protein tests can assess overall protein status or individual proteins, e.g., albumin, globulin, and fibrinogen.
• Abnormal levels can suggest inflammation, or other health issues.

Lipid Analysis

• Lipids serve as energy stores, structural components of cells, and are crucial for vitamin absorption.
• Lipoproteins transport lipids in the bloodstream.
• Analyses of lipids and lipoproteins are critical for diagnosing conditions like dyslipidemia, assessing overall health, and identifying potential issues.

Kidney Function Tests

• Kidney function tests measure the concentration and the quantity of waste products in urine.
• Kidney function impairment leads to elevated creatinine and urea levels.
• These tests help assess potential kidney pathology or problems.

Liver Function Tests

• Liver enzymes are elevated when there's liver damage.
• Bilirubin elevation can suggest liver issues or blood disorders.
• Tests provide information about the liver function.