(Week 1) LG 1 Liver Function

Overview of Liver Function Tests

  • Instructor: Professor Dr. Salar A. Ahmed

  • Institution: Aristotle University of Thessaloniki / University of Kurdistan - Hawler

  • Contact Information: 07504101917, salar.adnan@ukh.edu.krd

  • Lecture Title: Liver Function Tests

  • Key Takeaway: A healthy liver signifies a healthy body.

What is the Liver?

  • Largest Internal Organ: The liver is both an organ and a gland in the human body.

  • Homeostasis: Maintains the internal environment crucial for overall metabolism, detoxification, and removal of toxins.

  • Weight:

    • Males: 1.4 - 1.6 kg

    • Females: 1.2 - 1.4 kg

  • Functions: Over 500 vital functions impacting all body systems.

Functions of the Liver

  1. Metabolic Functions

    • Carbohydrate Metabolism: Regulates blood sugar levels, gluconeogenesis, glycogenolysis, and glycogenesis.

    • Hormone Metabolism: Inactivation of thyroid hormones, insulin, and glucagon.

    • Lipid Metabolism: Synthesizes fatty acids, lipoproteins, cholesterol, and participates in ketogenesis.

    • Protein Metabolism: Synthesizes plasma proteins and converts ammonia to urea.

    • RBC Production: Production occurs mainly in the fetus during the first trimester.

  2. Storage Functions

    • Stores glycogen, fat-soluble vitamins (A, D, E, K), vitamin B12, and trace elements like iron and copper.

  3. Excretory Functions

    • Essential for waste removal and bile excretion (cholesterol, bile pigments, and salts).

    • Synthesizes and secretes most blood antibodies.

  4. Synthetic Functions

    • Participates in blood formation and produces clotting factors (Factors V, VII, and fibrinogen).

  5. Detoxification and Protective Functions

    • Removes harmful substances from the blood and metabolizes drugs and hormones.

    • Performs phagocytosis to eliminate foreign compounds, converting ammonia to urea.

Assessment of Liver Functions via LFTs

  • Blood Tests: Measure liver function and assess for disease presence or extent. Useful indicators include:

    • Active liver damage (e.g., hepatitis)

    • Cholestasis (slowed bile flow)

  • Combination Approach: LFTs are complemented by patient history and physical examinations.

Abnormal Liver Test Indicators

  • Liver inflammation

  • Injury due to drugs, alcohol, toxins, viruses

  • Bile flow obstruction

  • Liver cancers

Signs of Potential Liver Disease

Non-specific Signs

  • Anorexia, fatigue, nausea, vomiting, mental confusion.

More Specific (Late Findings)

  • Jaundice, dark urine, abdominal swelling, peripheral edema.

Classification of Liver Function Tests (LFT)

  • Based on liver functions:

    1. Excretory functions

    2. Synthetic functions

    3. Metabolic functions

    4. Detoxification functions

    5. Storage functions

Tests Based on Liver Functions

Excretory Functions

  • Serum bilirubin

  • Urine bilirubin

  • Urine and fecal urobilinogen

  • Urine bile salts

  • Dye excretion tests

Detoxification Function

  • Blood ammonia determination

  • Hippuric acid test

Synthetic Function

  • Plasma proteins

  • Prothrombin time

Metabolic Function

  • Tests for carbohydrate metabolism

  • Tests for lipid metabolism

  • Tests for protein metabolism

Important Serum Tests

  1. Serum Total Bilirubin

    • Breakdown product of hemoglobin from old RBCs, indicating liver processing ability.

  2. Bromosulphthalein Excretion Test

    • Non-toxic dye to assess liver excretory function; <5% retention in normal individuals.

  3. Serum Enzymes

    • Alkaline phosphatase (ALP)

    • 5' nucleotidase (5'NT)

    • gamma-glutamyl transpeptidase (GGT)

  4. Galactose Tolerance Test

    • Evaluates liver metabolic capacity through galactose utilization.

  5. Serum Albumin

    • Synthesized by the liver, low levels indicate chronic damage.

Conclusion

  • The liver's various functions are crucial to maintaining the body's health, and liver function tests provide significant insight into its status and potential diseases.