Alcohol Screening

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Block C4 - Adolescence and Adulthood

Office:6th floor, Radiopoetro
Pre-test:3-6 questions, short-answer.
Post-test:Sometimes. Oral only.
Lab Report:
  • Introduction
  • Reagents/Equipment
  • Procedure
  • Result
  • Discussion
  • Conclusion
  • References

Please note: the block book (as of March 2013) uses the term "Kalium bichromate". However, in correct English, it should be called Potassium dichromate.


In a tightly woven, acid condition, alcohol in the sample will evaporate and react with Potassium dichromate. This will result in a color change from yellow to green, and then eventually blue.


  • Alcohol is also known as ethanol.
  • Alcohol gets between membranes and increases their fluidity. This causes toxic effects in the brain. The action potentials are altered, active transport gets impaired, and alcohol also affects neurotransmitter release.
  • Alcohol contains non-nutritive calories.
    • That is why heavy drinking is complicated by malnutrition and vitamin deficiency.
    • A combination of direct alcohol toxicity, malnutrition, vitamin deficiency, and systemic alcohol disorders (such as chronic liver disease) require a therapeutic program that includes: alcohol abstinence, well-balanced nutrition, vitamin substitution, and neurological rehabilitation.
  • Ingested alcohol (ethanol) is metabolized in the liver by ADH into Acetaldehyde.
    • In other words, ADH breaks ethanol down into acetaldehyde, and that Acetaldehyde is ethanol's oxidative metabolite.
    • Thiamine deficiency accelerates ethanol metabolism and the production of acetaldehyde.
    • Acetaldehyde reduces the activity of the thiamine-dependent enzyme called transketolase by a process called acetylation.
    • Acetaldehyde is oxidized in the liver by ALDH into acetate. Acetate is mostly used up by the peripheral tissues.
    • Acetaldehyde is highly reactive with lipids, proteins, and nucleic acids.
    • Acetaldehyde is electrophilic and helps covalent binding of protein residues to form acetaldehyde-protein adducts.
      • When acetaldehyde reacts with lipids (specially polyunsaturated fatty acids and cholesterol), it starts a process called lipid peroxidation.
      • Lipid peroxidation impairs cellular (and sub-cellular) membranes and generates free radicals.
  • GGT is an enzyme that helps with drug and xenobiotic detoxification.
    • Increased serum GGT levels can damage the liver.
    • Things that increase GGT:
      • Drugs: anticonvulsants, barbiturates, benzodiazepines.
      • Xenobiotics: nicotine, organic solvents.
      • Non-alcoholic liver diseases.


2011 Batch Pretest[edit]

  1. Name three types of drugs that increase GGT. Anticonvulsants, barbiturates, and benzodiazepams.
  2. What is the principle of alcohol screening? In a tightly woven and acid condition, alcohol in the sample will evaporate and react with potassium dichromate, resulting in a color change from yellow to green to blue.
  3. What type of vitamin deficiency ethanol causes? Thiamine.
  4. What does ADH convert ethanol to? Acetaldehyde.
  5. What does Acetaldehyde form with proteins and nucleic acids? Acetaldehyde-protein adducts.