Alcohols: Ethyl alcohol (Ethanol), Methanol, Isopropanol, and Ethylene Glycol, and Complications
- Alcohol levels can be estimated in blood, breath, and saliva.
- When collecting blood, then don’t clean the site with alcohol. Clean the site with an alcohol-free disinfectant like benzalkonium chloride.
- A blood test is the best sample for the estimation of alcohol.
- Blood samples in a living patient may be whole blood, serum, or plasma.
- The serum and blood alcohol ratio is 1:14.
- Blood in a cadaver is taken from the aorta.
- The blood must be capped to avoid the evaporation of alcohol.
- Collect blood in sodium fluoride or potassium oxalate.
- Use alcohol-free disinfectants. Take a blood sample without the use of any alcohol skin cleaning solution.
- Alcohol is volatile, so capped the bottle to avoid evaporation.
- Can store the blood when it is properly sealed for 14 days at room temperature or at 4 °C with or without preservative.
- For longer storage or nonsterile postmortem material, specimens use the preservative sodium fluoride.
Measurement can be done on the following samples:
- Blood alcohol level tested in serum or plasma or whole blood.
- Arterial blood sample higher than the venous sample.
- Capillary blood from the finger prick or ear lobules is about 70% to 85% of the arterial blood.
- The serum value is 18% to 20% higher than the whole blood level.
- Blood levels correlated by the law are whole blood samples.
- Serum: whole blood ratio is 1.03 to 1.35.
- Rainey, in 1995, gave a median serum/whole blood conversion ratio of 1.15 rather than 1.20.
- Breath test:
- The police mostly use breath tests; these are easy and can be done anywhere.
- A breath analyzer measures the concentration of ethanol at the end of deep expiration after the deep inspiration.
- Alcohol level: breath/blood alcohol ratio is 2100:1. Multiply the value by 2100.
- Breath alcohol = g/210 L
- The above value is equal to blood alcohol g/dL.
- Before performing the breath test wait for 15 minutes to rule out:
- Alcohol may be present in the mouth in case of recent drinking.
- Vomiting containing alcohol-rich gastric fluid.
- Alcohol-containing mouth wash.
- There should be no smoking.
- Some of the mouthwash produce a significant level 2 minutes after use, but it is no more after 10 minutes.
- Ketone bodies may interfere in the breath test.
- In case of a breath negative test, indicate some other medical emergencies.
- Saliva may be used where alcohol concentration is 9% higher than that in the whole blood.
- This is an easy and noninvasive method.
- Urine alcohol sample is noninvasive and easy to collect the sample.
- 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.
- This is variable, so it is better to empty the bladder and then collect urine after 20 to 30 minutes.
- It can detect the ingestion of alcohol within the previous 8 hours.
- Urine samples are not recommended because of the variable blood/urine ratio and the stasis of the urine in the urinary bladder.
- But urine can be used for screening purposes.
- Quantitation of the alcohol level is done for therapeutic or legal purposes.
- The alcohol level is done to diagnose alcohol intoxication.
- Alcohol level may be done in cases of coma, cerebral trauma, and drug overdose.
- To differentiate alcoholic intoxication coma from a diabetic coma.
- This test is also done for alcoholism.
- This test is done on the drivers.
Definition of alcoholic person:
- Alcohol shows a range of action on the central nervous system extending from sedation to anesthesia, and intake of alcohol leads to impairment of judgment and thinking and altered behavior.
- The legal definition of alcohol intake is when a person has a blood level of alcohol 0.1 g/dl or 100 mg/dL.
- Alcohol is Ethanol, and it is readily absorbed from the GI tract.
- The peak level is within 40 to 70 minutes after the intake.
- The liver enzyme dehydrogenase metabolizes ethanol into acetaldehyde.
- 90% of alcohol is metabolized in the liver.
- This acetaldehyde is converted into acetic acid by the enzyme Aldehyde Dehydrogenase.
- For the diagnosis of alcoholism:
- A major criterion is blood alcohol level >15 mg/dL at any time.
- The minor criterion is blood alcohol concentration is >300 mg/dL at any time, and blood alcohol concentration is 100 mg/dL.
- Toxic concentration blood alcohol level is ≥200 mg/dL.
- The lower limit to detect blood alcohol level is 100 µg/mL.
Alcohol (Ethyl alcohol) metabolism:
- Ethanol easily diffuses into the body fluids and is partially cleared in the urine and other body excretion.
- Its major metabolic pathway is its conversion into acetaldehyde by the alcohol dehydrogenase enzyme in the liver.
- Acetaldehyde is converted into acetate by the acetaldehyde dehydrogenase enzyme.
- Ethanol metabolite acetaldehyde leads to acidosis and ketosis called Alcoholic ketoacidosis.
- Ethanol converted to acetaldehyde.
- Headache, flushing, and hangover are due to acetaldehyde before it is metabolized to acetate.
- Ethanol converted to acetaldehyde.
- Once the peak level is reached, then its level decreases.
Effect of ethanol on the body:
- Ethanol depresses the CNS and ultimately may lead to coma and death.
- ≤50 mg/dL = Euphoria and decreased inhibitions.
- 100 to 300 mg/dL = Incoordination and decreased orientation.
- >400 mg/dL = Coma and death.
- CNS dysfunction is more pronounced when:
- Absorptive phase: Ethanol concentration in the blood is increasing.
- Elimination phase: When the level of alcohol is declining.
- Alcohol causes diuresis by inhibiting the secretion of the ADH (antidiuretic hormone) by the posterior pituitary.
- It also inhibits the secretion of oxytocin. Because of this property, this is used to stop uterine contractions in premature labor.
- Alcohol blood concentration level of 100 mg/dL has been established to limit car/truck driving in most states in the United States.
- While in 17 states, this limit is 80 mg/dL.
- When ethanol is used with other CNS-depressant drugs, then ethanol exerts potentiation or synergistic depressant effect.
- Alcohol is present in the blood, urine, stomach contents, and breath.
- Saliva’s alcohol level is 9% higher than blood.
- The blood-alcohol level of 50 to 100 mg/dL causes:
- Slowing of reflexes.
- Impaired vision.
- The blood-alcohol level of >100 mg/dL causes:
- Signs of CNS depression seen.
Toxic Effect of blood alcohol:
- A blood alcohol level >300 mg/dl is usually associated with a coma.
- The blood-alcohol level of >400 mg/dL is fatal, and death may occur.
- The pregnant ladies taking alcohol will have low-birth-weight babies.
- Alcoholic mother babies will have mental retardation and fetal alcohol syndrome (an irreversible congenital disorder).
- Nutritional and metabolic studies have demonstrated that alcohol can cause hypertension.
Level of the alcohol intake:
- The blood-alcohol level will increase roughly 15 to 25 mg/dL when adult taking:
- An ounce of whiskey or.
- 12 ounce of the bear or.
- One glass of wine.
- Women absorb more quickly than men and show a 35% to 45% higher blood alcohol level. During the menstrual cycle, the peak occurs more rapidly. Birth control pills cause higher levels and sustain it.
- The use of sedatives like barbiturates and benzodiazepines with alcohol is hazardous and may lead to death by respiratory depression.
The complication of alcohol in chronic drinkers:
- Chronic use of alcohol may lead to:
- Cirrhosis of the liver.
- The degenerative changes in the brain.
- The degenerative changes in the skeletal muscles.
- Chronic alcoholics may have nutritional and vitamin deficiencies.
The rate of elimination of ethanol from the blood circulation:
- Men = 11 to 22 mg/dL/ hour.
- Average level is = 15 mg/dL/hour.
- Women = 11 to 22 mg/dL/hour.
- Average level is = 18 mg/dL/hour.
- Drinking habits also influence the elimination rate.
- For example = Alcoholics have an average elimination rate of about 30 mg/dL/hour.
Alcohol or ethanol intake effects on the body (Complications of alcohol):
- Ethanol ingestion leads to hypoglycemia and ketonemia because of the inhibition of gluconeogenesis.
- Lactate accumulates and competes with uric acid for excretion through the kidney. So serum uric acid level is increased.
- When alcohol is taken with fatty meals, it leads to hypertriglyceridemia, which may persist for more than 12 hours.
- The moderate intake of alcohol for one week leads to increased serum triglyceride >20 mg/dL.
- The toxic level of alcohol stimulates the release of:
- Increased intake of alcohol leads to:
- The decreased plasma testosterone level in the men.
- There is an abnormal pituitary, adrenocortical, and medullary function.
- Alcohol ingestion after metabolized leads to acetaldehyde formation, which causes damage to mitochondria of hepatocytes, and H+ leads to fat accumulation.
- In chronic alcoholism, there is an increased level of acetaldehyde and acetate.
- The acetate enters the acetyl-CoA cycle and leads to increased synthesis of fatty acids, and the result is fatty liver.
- Ethanol leads to diuresis by inhibiting the ADH from the posterior pituitary.
- It also inhibits the secretion of Oxytocin from the posterior pituitary. So can be used in stopping uterine contraction in premature labor.
- When alcohol ethanol is not available, people may use other alcohols like methanol (methyl alcohol), also called wood alcohol, isopropanol (rubbing alcohol), and ethylene glycol (antifreeze alcohol). Sometimes these are present as a contamination in the ethanol. All these are associated with toxicities.
- Their metabolism has direct toxic effects or from their metabolites.
Methanol (Wood alcohol):
- It is used as a solvent in several commercial products.
- Alcoholics use it because of the low price.
- Or this may be contamination in the ethanol.
- S/S of CNS is less severe as compared to ethanol.
- The liver alcohol dehydrogenase (ADH) enzyme in the liver converts it into formaldehyde.
- Formaldehyde is oxidized rapidly by the aldehyde dehydrogenase to formic acid.
- Formic acid will accumulate in the blood and leads to metabolic acidosis with a latent period of 12 to 27 hours.
- The patient will have toxicity due to formate (formic acid).
Isopropanol (Rubbing alcohol):
- This is easily available to the general population.
- It is used as rubbing alcohol.
- This has twice the CNS depression effect.
- This is not as toxic as methanol.
- This has a short half-life of 3 to 6 hours due to rapid conversion by alcohol dehydrogenase (ADH) to acetone.
- Acetone is eliminated slowly through respiration and urine.
- Acetone has the same property of CNS depressant as ethanol, but it is prolonged.
- Severe isopropanol toxicity may lead to come or death.
- Toxic level:
- >400 mg/L = Indicates severe toxicity.
- >1000 mg/L = Patient will go into coma.
- The presence of acetone in the urine and blood, when it is at a high level will indicate isopropanol poisoning.
- This is used as an antifreeze. It is also used in the industry in polyester fiber make.
- This is also CNS depressaant.
- Then effect the heart and is followed by the kidneys.
- It is oxidized to glycolic acid and then to oxalate.
- There is severe metabolic acidosis with an increased anion gap.
- Can detect ethylene glycol and its metabolite glycolic acid in the blood (serum).
- can see oxalate and hippurate crystals in the urine.
- Dialysis is needed if the glycolic acid level is >50 mg/dL.
Comparison of various types of alcohols intoxication (poisoning):
|Type of alcohol||Metabolic acidosis||Anion gap||Urine ketones||Urine oxalate crystals||Serum acetone|
|Isopropanol||Not present||Not increased||Positive||Negative||Positive|
|Ethylene glycol||Present||Increased||Negative||1/3 of cases present||Negative|
Long term effect of chronic alcoholism are:
- Cardiovascular diseases.
- Seizures like epilepsy.
- Increased risk for infections like tuberculosis, HIV, and pneumonia.
- Alcoholic neuropathy.
- Gastritis and pancreatitis.
The normal level of alcohol and interpretations:
|Clinical interpretation||Level of the alcohol in the blood|
|Negative||Not detected in the blood|
|Considered negative||<10 mg/dL|
|Considered negative by the USA transportation||<20 mg/dL|
|Considered positive||>40 mg/dL|
|Considered drunk driver||>80 mg/dL|
|The toxic level of ethanol||>100 mg/dL|
|Fatal level of ethanol||>300 to 400 mg/dL|
|The toxic level of methanol||>20 mg/dL|
|The toxic level of isopropanol||>40 mg/dL|
- The lower limit of detection is 10 mg/dL.
- >80 mg/dL is considered positive for driving under the influence in most of the states.
- >300 to 400 mg/dL is considered fatal.
- >300 mg/dL.
- In high dose coma, blood alcohol should be >300 mg/dL; otherwise, rule out diabetic acidosis and hypoglycemia.
- A blood alcohol level of >150 mg/dL without any evidence of intoxication suggests that the alcoholic patient has increased tolerance.
Clinical presentation of the alcoholic person:
|Blood alcohol level||Patients presentations|
|100 to 200 mg/dL||The 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||The patient’s condition is critical, and they may die due to respiratory paralysis.|
|More than 2000 mg/mL||Death due to respiratory paralysis.|
Clinical stages of alcoholic intoxication:
|Blood alcohol concentration (% weight/volume)||Urine ethanol (% W/V)||Clinical symptoms|
|<0.05%||0.01 to 0.07||Feels Soberness and calm|
|0.05 to 0.1%||0.03 to 0.16||Feels euphoric|
|0.1 to 0.2%||0.07 to 0.30||Feels excited|
|0.2 to 0.3%||0.12 to 0.40||Starts confusion|
|0.3 to 0.4%||0.20 to 0.50||Now is stuporous|
|>0.4%||0.25 to 0.60||Goes into a coma, and death may occur|
- (modified from ASCP )
|The blood alcohol concentration in g/dL||Clinical Stage of alcoholic influence||Clinical presentation|
|0.01 to 0.05||Subclinical||
|0.03 to 0.12||Europa||
|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||It is due to respiratory failure|
Lab diagnosis of alcohol intoxication:
- Blood test: Most court of the law follows the national safety council on alcohol intake.
The blood level of alcohol Court of law recommendations <0.05% (50 mg/dL) No influence of the alcohol 0.05% to 0.1% (50 to 100 mg/dL)
- This is a liberal wide zone in which alcohol influence is present.
- Courts suggest observing the person’s behavior and circumstances.
- The above situation decision will decide to arrest.
>0.1% (>100 mg/dL) Definite evidence of alcohol intoxication, because most people at this level will:
- Lost measurable extent of clearness of intellect.
- Lost self-control
- The American medical association (AMA), the council on scientific affairs (1986), suggests that a 0.05% blood alcohol level suggests alcohol and impaired driving.
- Breath test: it is discussed in detail above.
- The breath to blood ratio is 0.00048:1.
- Urine test: This is not recommended because of the high blood/urine ratio.
- This is also a noninvasive method.
- This is recommended first to empty the bladder and then collect urine after 20 to 30 minutes.
- Saliva ethanol: This is easy to collect saliva and is a noninvasive method.
- Saliva ethanol level is about 9% higher than the whole blood.
- Laboratory tests to evaluate chronic alcoholism:
- γ-GT (GGT) will give information about the damage caused by alcohol use and will be raised.
- GGT has a sensitivity of 70% (range maybe 63% to 81%).
- AST (SGPT) has the same role like GGT. It is raised in 50% of the cases (range maybe 27% to 77%).
- MCV detects the deficiency of folic acid. This may be abnormal in 60% of the cases (range maybe 26% to 90%).
- Other abnormalities found in <40% of the cases are:
- Hypochloremic alkalosis.
- Increased lactic acid.
- Metabolic acidosis with increased anion gap.
- γ-GT (GGT) will give information about the damage caused by alcohol use and will be raised.