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Alcohol (Ethanol)

Study guide:


  • Major Metabolic Pathway:

    • Ethanol -> Acetaldehyde -> Acetate (liver) -> CO2 + H2O (peripheral tissues).

  • Alternative Metabolic Pathway:

    • Microsomal Ethanol Oxidizing System MEOS (CYP2E1).

  • The main ALDH (Acetaldehyde dehydrogenase) for acetaldehyde oxidation is ALDH2 (mitochondrial enzyme).

  • Pure ethanol produces 7kcal/g addition of sugars and other additives will increase the caloric value.

  • 1 unit of alcohol = 8 g of ethanol.

  • 1 unit of alcohol: (see Figure 3)

Figure 1

  • 90% of ethanol is oxidized in the liver through the major pathway.

  • Disulfiram inhibits Acetaldehyde dehydrogenase; thus, ↑acetate (toxic).   

Figure 2

  • Daily maximum for men is 3 units and 2 units for women. 

  • Alcohol is active at GABA receptors and glutamate receptors in the brain -> activate endogenous opioid receptors.


  • Problem drinker: drinking is causing physical, psychological, and/or social impairment.

  • Heavy drinker: drinking significantly more (quantity and/or frequency) than the healthy safe limits.

  • Binge drinker: drinking excessively in short bouts (24P28 hrs long) followed by long periods of abstinence.

  • Alcohol dependence: physical dependence and addition to alcohol (alcohol dependence syndrome).

  • Addiction: Chronic disease characterized by continued behavior or use of a substance, even after experiencing negative social, psychological, or physical consequences.

  • Addiction to alcohol or another drug: a disease process characterized by the continued use of a specific psychoactive substance despite physical, psychological, or social harm.

  • Tolerance: When the effect of a constant dose becomes diminished or an increasing dose is required to achieve the desired result.

  • Withdrawal syndrome: Signs and/or symptoms resulting from abrupt removal or rapid decrease in use of a substance.

Causes & Risk factors for Alcohol Dependence:

  • Genetic factors: people with close relatives who are alcoholics are at increased risk of alcoholism.

  • Environmental factors: household and peer effect.

  • Biochemical factors: abnormalities in the alcohol dehydrogenase.

  • Psychiatric diseases: depression and/or anxiety.

  • Increases in Society consumption (per capita consumption).

Clinical Presentation:

  • Symptoms of alcohol dependence:

    • Unable to stop at a certain drink limit

    • Spending a lot of time drinking

    • Missing meals

    • Memory lapses

    • Blackout

    • Restless without drinking

    • Trembling after drinking

    • Morning retching and vomiting

    • Night sweats

    • Increased tolerance

    • Hallucinations and frank delirium tremens

    • Behavioral effects of alcohol:


  • Screening

    • CAGE (>1 positive answer might suggest alcohol misuse):

      • Cut down?

      • Annoyed?

      • Guilty?

      • Eye-opener?

    • MAST (Michigan Alcoholism Screening Test) questionnaire (25 items).

Diagnostic criteria (if present):

Lab tests:


  • LFTs:

    • Elevated g-GT

    • ↑AST: ALT ratio 2:1

  • CBC:

    • Elevated MCV

    • Macrocytic anemia (due to folate deficiency)

    • Microcytic anemia (due to GI bleeding)

  • Hypertriglyceridemia

  • Hyperuricemia

  • Hypocalcemia

  • Hypomagnesemia

  • Thiamine deficiency

  • ↓Testosterone

Diagnostic Criteria for Alcohol Withdrawal Syndrome (Any 3 of the following):

  • Tremor of outstretched hands, tongue or eyelids

  • Sweating

  • Nausea, retching, or vomiting

  • Tachycardia, or hypertension

  • Anxiety

  • Psychomotor agitation

  • Headache

  • Insomnia

  • Malaise or weakness

  • Transient hallucinations or illusions (tactile, visual, auditory)

  • Grand mal convulsions (general seizures)



  • Non-pharmacological:

    • Motivational approach:

      • Precontemplation→ contemplation→ determination→ action→ maintainance.

    • Alcoholics Anonymous (AA): is the best treatment.

  • Pharmacological treatment:

In general, outpatient management is appropriate for patients with mild withdrawal symptoms

and are having good social support. While inpatient management is reserved for patients who have severe withdrawal symptoms or poor social support.

Follow up:

  • 30-50% of alcohol-dependent drinkers are abstinent or drinking less in 2 years after using the traditional interventions.


  • Delirium Tremens (DTs):

    • Most serious withdrawal state, which is a medical emergency (high mortality rate 20%).

    • Usually after 1P3 days after alcohol cessation but can occur after 1 week

    • Characterized by: tactile hallucinations, confusion, sweating, increased tachycardia, and high BP.

    • Benzodiazepine is the best treatment and preventive method.


  1. Agabegi, Steven S, Elizabeth D Agabegi, and Adam C Ring. StepNUp To Medicine. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins, 2013. Print.

  2. Kumar, Parveen J, and Michael L Clark. Kumar & ClarkTs Clinical Medicine. Print.

  3. S.Lipsky, Martin, and Mitchell S.King. 3rd ed. China: Lippincott Williams & Wilkins, a Wolters Kluwer business., 2011. Print.

  4. Lieberman, Michael, Allan D Marks, and Colleen M Smith. MarksT Basic Medical Biochemistry. Philadelphia: Wolters Kluwer

    Health/Lippincott Williams & Wilkins, 2009. Print.

  5. Medscape,. mAlcoholic Liver Disease P Pathophysiological Aspects And Risk Factorsm. N.p., 2015. Web. 11 Oct. 2015. (Figure 1)

  6.,. mReduce Alcohol P Mobile Subsitem. N.p., 2015. Web. 24 Sept. 2015 (Figure 2).

  7. Sloane, Philip D. Essentials Of Family Medicine. Philadelphia: Wolters Kluwer/Lippincott, Williams & Wilkins, 2008. Print.

  8. Agabegi, Steven S, Elizabeth D Agabegi, and Adam C Ring. StepNUp To Medicine. Philadelphia: Wolters Kluwer/Lippincott

Written by:       Roaa Amer

Reviewed by:    Abdulrahman AlNasser

                        Rana AlZahrani

Format Editor:  Adel Yasky

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