Methanol toxicity: Difference between revisions

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'''Methanol toxicity''' is a form of [[poisoning]] that occurs when the body is exposed to excessive amounts of [[methanol]], a simple [[alcohol]] commonly used in industrial and automotive applications. Methanol is toxic due to its metabolic products, [[formaldehyde]] and [[formic acid]], which can cause severe [[metabolic acidosis]], [[neurological dysfunction]], and [[blindness]].
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== Causes ==
== Methanol toxicity ==
Methanol toxicity can occur through ingestion, inhalation, or skin absorption. The most common cause is accidental or intentional ingestion of methanol-containing substances, such as [[antifreeze]], [[windshield washer fluid]], and certain types of [[paint thinner]] and [[solvent]]s.
[[File:Methanol_Lewis.svg|thumb|right|200px|Lewis structure of methanol]]


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'''Methanol toxicity''' is a form of [[poisoning]] that occurs when methanol, a type of [[alcohol]], is ingested, inhaled, or absorbed through the skin. Methanol is a colorless, volatile liquid with a distinctive odor, commonly used as an industrial solvent, antifreeze, and fuel. It is also found in small amounts in various consumer products.
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== Pathophysiology ==
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Methanol itself is not highly toxic, but it is metabolized in the [[liver]] to formaldehyde and then to formic acid, which are highly toxic metabolites. The enzyme [[alcohol dehydrogenase]] converts methanol to formaldehyde, and [[aldehyde dehydrogenase]] further converts formaldehyde to formic acid. Formic acid accumulation leads to metabolic acidosis and can cause damage to the [[optic nerve]], resulting in [[blindness]].
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== Symptoms ==
== Symptoms ==
The symptoms of methanol toxicity can be divided into early and late stages. Early symptoms, which can occur within a few hours of exposure, include [[headache]], [[dizziness]], [[nausea]], [[vomiting]], and [[abdominal pain]]. Late symptoms, which can occur 12 to 24 hours after exposure, include [[blurred vision]], [[photophobia]], [[coma]], and [[seizure]]s.
The symptoms of methanol toxicity can vary depending on the dose and duration of exposure. Initial symptoms may include:
* [[Headache]]
* [[Dizziness]]
* [[Nausea]]
* [[Vomiting]]
* [[Abdominal pain]]
 
As the condition progresses, more severe symptoms can develop, such as:
* [[Visual disturbances]] (e.g., blurred vision, "snowfield" vision)
* [[Blindness]]
* [[Seizures]]
* [[Coma]]
* [[Respiratory failure]]


== Diagnosis ==
== Diagnosis ==
Diagnosis of methanol toxicity is based on a combination of clinical history, physical examination, and laboratory tests. The most important laboratory test is the measurement of serum methanol concentration. Other useful tests include [[arterial blood gas]] analysis, [[serum electrolyte]] measurement, and [[lactate]] level.
Diagnosis of methanol toxicity is based on clinical presentation and laboratory tests. Key diagnostic indicators include:
* Elevated [[anion gap metabolic acidosis]]
* Increased serum methanol concentration
* Presence of formic acid in the blood


== Treatment ==
== Treatment ==
The treatment of methanol toxicity involves supportive care, [[antidote]] therapy, and in severe cases, [[hemodialysis]]. The antidote for methanol toxicity is [[fomepizole]] or [[ethanol]], which works by inhibiting the enzyme [[alcohol dehydrogenase]], thereby preventing the formation of toxic metabolites.
The primary goals of treatment are to inhibit methanol metabolism, correct metabolic acidosis, and remove methanol and its toxic metabolites from the body. Treatment options include:


== Prognosis ==
* '''Fomepizole''': An inhibitor of alcohol dehydrogenase, preventing the conversion of methanol to formaldehyde.
The prognosis of methanol toxicity depends on the amount of methanol ingested, the time elapsed before treatment, and the presence of complications. With prompt and appropriate treatment, the prognosis can be good. However, severe cases can result in permanent neurological damage or death.
* '''Ethanol''': Competes with methanol for alcohol dehydrogenase, reducing the formation of toxic metabolites.
* '''Sodium bicarbonate''': Used to correct metabolic acidosis.
* '''Hemodialysis''': Effective in removing methanol and formic acid from the blood.


== Prevention ==
== Prevention ==
Prevention of methanol toxicity involves proper storage and labeling of methanol-containing substances, education about the dangers of methanol ingestion, and prompt treatment of suspected cases.
Preventing methanol toxicity involves minimizing exposure to methanol-containing products and ensuring proper labeling and storage. Public education on the dangers of methanol ingestion and the importance of seeking immediate medical attention if exposure occurs is crucial.
 
== Related pages ==
* [[Alcohol poisoning]]
* [[Formaldehyde]]
* [[Metabolic acidosis]]
* [[Optic nerve]]


[[Category:Toxicology]]
[[Category:Toxicology]]
[[Category:Medical emergencies]]
[[Category:Alcohols]]
[[Category:Alcohols]]
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Revision as of 11:41, 15 February 2025


Methanol toxicity

Lewis structure of methanol

Methanol toxicity is a form of poisoning that occurs when methanol, a type of alcohol, is ingested, inhaled, or absorbed through the skin. Methanol is a colorless, volatile liquid with a distinctive odor, commonly used as an industrial solvent, antifreeze, and fuel. It is also found in small amounts in various consumer products.

Pathophysiology

Methanol itself is not highly toxic, but it is metabolized in the liver to formaldehyde and then to formic acid, which are highly toxic metabolites. The enzyme alcohol dehydrogenase converts methanol to formaldehyde, and aldehyde dehydrogenase further converts formaldehyde to formic acid. Formic acid accumulation leads to metabolic acidosis and can cause damage to the optic nerve, resulting in blindness.

Symptoms

The symptoms of methanol toxicity can vary depending on the dose and duration of exposure. Initial symptoms may include:

As the condition progresses, more severe symptoms can develop, such as:

Diagnosis

Diagnosis of methanol toxicity is based on clinical presentation and laboratory tests. Key diagnostic indicators include:

Treatment

The primary goals of treatment are to inhibit methanol metabolism, correct metabolic acidosis, and remove methanol and its toxic metabolites from the body. Treatment options include:

  • Fomepizole: An inhibitor of alcohol dehydrogenase, preventing the conversion of methanol to formaldehyde.
  • Ethanol: Competes with methanol for alcohol dehydrogenase, reducing the formation of toxic metabolites.
  • Sodium bicarbonate: Used to correct metabolic acidosis.
  • Hemodialysis: Effective in removing methanol and formic acid from the blood.

Prevention

Preventing methanol toxicity involves minimizing exposure to methanol-containing products and ensuring proper labeling and storage. Public education on the dangers of methanol ingestion and the importance of seeking immediate medical attention if exposure occurs is crucial.

Related pages