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Sample

Precautions

  1. Use alcohol-free disinfectants.
  2. Alcohol is volatile so capped the bottle to avoid evaporation.
  3. Can store the blood when it is properly sealed for 14 days at room temperature or at 4 °C with or without preservative.
  4. For longer storage or nonsterile postmortem, specimen use the preservative, sodium fluoride.

Measurement can be done on the following samples:

  1. Blood alcohol level tested in serum or plasma or whole blood.
  2. Breath alcohol where the blood: breath alcohol ratio is 2100:1.
    1. Breath alcohol = g/210 L 
      1. This above value is equal to blood alcohol g/dL.
    2. Before performing the breath test wait for 15 minutes to rule out:
      1. Alcohol may be present in the mouth in case of recent drinking.
      2. Vomiting containing alcohol rich gastric fluid.
      3. Alcohol-containing mouth wash.
  3. Salive may be used where the concentration of alcohol is 9% higher than that in the whole blood.
    1. This is an easy and noninvasive method.
  4. Urine alcohol sample is noninvasive and easy to collect the sample.
    1. During the post-absorptive stage after alcohol intake, the concentration of the alcohol in the urine is roughly 1.3 times that in the blood.
    2. This is variable, so better empty the bladder and then collect urine after 20 to 30 minutes.
    3. It can detect ingestion of alcohol within the previous 8 hours.

Indications

  1. Quantitation of the alcohol level is done for therapeutic or legal purposes.
  2. Alcohol level is done to diagnose alcohol intoxication.
  3. Alcohol level may be done in cases of coma, cerebral trauma, and drug overdose.
  4. To differentiate alcoholic intoxication coma from diabetic coma.
  5. This test is also done for alcoholism.
  6. This test is done on the drivers.

Pathophysiology

  1. Alcohol is Ethanol and it is readily absorbed from the GI tract.
    1. Peak level is within 40 to 70 minutes after the intake.
  2. Ethanol is metabolized by the liver enzyme dehydrogenase into acetaldehyde.
    1. 90% of alcohol is metabolized in the liver.
    2. This acetaldehyde is converted into acetic acid by the enzyme Aldehyde Dehydrogenase.
  3. Ethanol metabolite acetaldehyde leads to acidosis and ketosis called Alcoholic ketoacidosis. 
    1. Ethanol converted to acetaldehyde.
      1. Headache, flushing, and hangover are due to acetaldehyde before it is metabolized to acetate.

 

  1. Once peak level is reached then its level decreases.
  2. Ethanol depresses the CNS and ultimately may lead to coma and death.
    1. ≤50 mg/dL = Euphoria and decreased inhibitions.
    2. 100 to 300 mg/dL = Incoordination and decreased orientation.
    3. >400 mg/dL = Coma and death.
    4. CNS dysfunction is more pronounced when:
      1. Ethanol concentration is increasing (absorptive phase).   
        1. Than when it is declining (elimination phase).
    5. Alcohol blood concentration level of 100 mg/dL has been established a limit for car/truck driving in most of the states in the United States.
      1. While in 17 states this limit is 80 mg/dL.
    6. When ethanol is used with other CNS-depressant drugs, then ethanol exerts potentiation or synergistic depressant effect.
  3. Alcohol is present in blood, urine, stomach contents, and breath.
    1. Saliva alcohol level is 9% higher than blood.
  4. The blood alcohol level of 50 to 100 mg/dL causes:
    1. Slowing of reflexes.
    2. Flushing.
    3. Impaired vision.
  5. The blood alcohol level of >100 mg/dL causes:
    1. Signs of CNS depression seen.
    2. Hypotension.
  6. Blood alcohol level >300 mg/dl is usually associated with coma.
    1. The blood alcohol level of >400 mg/dL is fatal and death may occur.
  7. The urine sample and blood alcohol levels are equal, while in the saliva will have 1.2 times of blood level.
  8. The blood alcohol level  will be roughly 25 mg/dL when adult taking:
    1. An ounce of whiskey or. 
    2. 12 ounce of the bear or. 
    3. One glass of wine.
  9. Use of sedatives like barbiturates and benzodiazepines with alcohol is very dangerous and may lead to death by respiratory depression.
  10. Chronic use of alcohol may lead to:
    1. Cirrhosis of the liver.
    2. The degenerative changes in the brain.
    3. The degenerative changes in the skeletal muscles.
    4. Chronic alcoholics may have nutritional and vitamin deficiencies.

  1. The rate of elimination of ethanol from the blood circulation.
    1. Men = 11 to 22 mg/dL/ hour.
      1. Average level is = 15 mg/dL/hour.
    2. Women = 11 to 22 mg/dL/hour.
      1. Average level is = 18 mg/dL/hour.
    3. The elimination rate also influenced by the drinking habit.
      1. For example = Alcoholics have an average elimination rate of about 30 mg/dL/hour.
  2. Alcohol or ethanol intake effects on the body are:
    1. Ethanol ingestion leads to hypoglycemia and ketonemia because of inhibition of gluconeogenesis.
    2. Lactate accumulates and competes with uric acid for excretion through the kidney. So serum uric acid level is increased.
    3. When alcohol is taken with fatty meals, leads to hypertriglyceridemia and this may persist for more than 12 hours.
      1. In case of moderate intake of alcohol for one week leads to increased serum triglyceride >20 mg/dL.
    4. The toxic level of alcohol stimulates the release of:
      1. Cortisol.
      2. Catecholamines.
    5. Increased intake of alcohol leads to:
      1. The decreased plasma testosterone level in the men.
      2. There is an abnormal pituitary, adrenocortical and medullary function.
    6. Alcohol ingestion after metabolized leads to acetaldehyde formation which causes damage to mitochondria of hepatocytes and H+ leads to fat accumulation.
      1. This system increases in chronic alcoholism and increased the level of acetaldehyde and acetate.
      2. The acetate enters the acetyl-CoA cycle and leads to increased synthesis of fatty acids and the end result is fatty liver.
    7. Ethanol leads to diuresis by inhibiting the ADH from the posterior pituitary.
      1. It also inhibits the secretion of the Oxytocin from the posterior pituitary. So this can be used in stopping uterine contraction in the premature labor.

  1. Complications of chronic alcoholism are:
    1. Anemia.
    2. Cancers.
    3. Cardiovascular diseases.
    4. Cirrhosis.
    5. Dementia.
    6. Depression.
    7. Seizures like epilepsy.
    8. Gout.
    9. Hypertension.
    10. Increased risk for infections like tuberculosis, HIV and pneumonia.
    11. Alcoholic neuropathy.
    12. gastritis and pancreatitis.

Normal

Critical Value

Blood alcohol level

 Patients presentations

100 to 200 mg/dL

Patient has emotional instability and there is a loss of critical judgment 

200 to 300 mg/dL

The patient is confused with impaired balance and disorientation.

300 to 400 mg/dL

The patient is unable to walk or stand and is stuporous.

More than 500 mg/dL

The patient is in a coma with depressed respiration and slow circulation.

More than 1500 mg/dL

Patient condition is critical and may die due to respiratory paralysis.

More than 2000 mg/mL

Death due to respiratory paralysis.

Clinical effect depending on the blood alcohol concentration:

Blood alcohol concentration (%)   Clinical symptoms
<0.05% Feels Soberness and calm
0.05 to 0.1% Feels euphoric
0.1 to 0.2% Feels excited
0.2 to 0.3% Stars confusion
0.3 to 0.4% Now is stuporous
>0.4% Goes into coma and death may occur
Blood alcohol concentration g/dL Stage of alcoholic influence
0.01 to 0.05 Subclinical
0.03 to 0.12 Europhia
0.09 to 0.25 Excitement
0.18 to 0.30 Confusion
0.25 to 0.40 Stupor
0.35 to 0.50 Coma
0.45 + (>0.45) Death

Possible References Used

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