Toxicology Flashcards
Small amounts of substances that produce injury
Toxins or poisons
What are 2 things that lab assays analyze?
- Qualitative (detect their presence)
- Quantitative (detect their amounts)
Is the typical blood screen quantitative or qualitative?
Qualitative- most people want to see if the drug is present- they dont really care how much is present
What is something that is important to determine before ordering a drug screen?
What is included in that specific ‘drug screen’
-this is different depending on which lab you are ordering from
Does timing matter when you are checking levels of toxins
Yes- certain toxins are only present for a short time, or they are only found in the blood, urine, or gastric acid
What is the most reliable source for determining the presence of toxins within a few hours of ingestion?
Gastric fluid
Describe levels of heroin and cocaine
Blood levels are only elevated for a short period of time
How do you test if ingestion occured more than a few hours before presentation
Urine levels
What compounds are better tested in blood because the urine excretion is minimal
-Lead or carbon monoxide
When quantitative results are needed, _____ is the only suitable fluid
BLOOD
What types of patient are usually given tox screens?
Patients that present with…
- coma
- confusion
- delirium
Can you overdose on acetaminophen?
Yes- when you take them in amounts that exceed metabolic capabilities
What effects does overdosing on acetaminophen have on the body?
- Causes renal toxicity
- Can produce acute tubular necrosis along with hepatic toxicity
When should levels be drawn if acetaminophen poisoning is suspected?
4 hours after ingestion- and levels should be more than 150 ug/mL to indicate toxicity
HOw should levels be drawn for people with acetaminphen toxicity?
-Should have levels drawn several times in the first few hours of observation
What is the most common type of toxicity?
Ethanol alcohol
T/F- Blood alcohol levels correlate with patterns of toxicity
True
How can chronic alcohol abuse be detected?
- Increased MCV
- Increased GGT
- Along with a positive drug screen
This is an odorless colorless gas that is produced from the incomplete combustion of hydrocarbons
Carbon monoxide
What percentage of deaths due to toxins does carbon monoxide cause?
50%- and 1/3 are accidental
How does carbon monoxide poison people
It binds to hemoglobin and prevents oxygen transport
Are the symptoms related to the amount of exposure in carbon monoxide?
Yes- they start with fatigue and headache and can progress to neurological deficit and cardiac & cerebral ischemia, and lactic acidosis
What are other S&S that someone has carbon monoxide poisoning?
-Other family members are involved
What is the most common cause of fatal poisoning in children?
Accidental ingestion of excess IRON
What is the pathogenesis of iron poisoning
Iron is absorbed by the intestine and stored in the liver- so too much iron can damage the liver and causes mucosal injury
-Leads to vomiting, GI bleeding, and abdominal pain
When does the amount of iron begin to effect the body?
- When the amount of iron ingested exceeds the binding capacity of transferrin
- Free iron causes damage to many cells
- This causes shock and lactic acidosis
What levels of iron produce toxicity?
When levels are over 100 ug/dL
What is the major source of lead
Lead paint in houses or on toys
What are S&S of lead poisoning
- Lowered intelligence
- Developmental delay
- Abdominal pain
- Neuropathy
- Anemia
What levels of lead produce toxicity?
over 40 ug/dL
When were tricyclic antidepressants prescribed?
-To patients that are prone to suicide attempts
What is amoung the most common encountered toxic agents?
Tricyclic Antidepressants
How is overdose on TCAs seen clinically?
-Overdose results in an anticholinergic pattern is seen and cardiac arrythmia is possible
What is the most typical methodology for testing drugs
-Immunoassays
Causes of False Positives…
- Occur with compounds that are chemically similar to the abused drug in question
- Poppy seeds
- Cocoa tea
- Sympathomimetic drugs are chemically similar to amphetamines
False negatives
- Urine sample from another person
- Water added to the sample to dilute the urine
- Chlorine bleaches added to denature the proteins after collection
