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71 Cards in this Set
- Front
- Back
A 25y/o female in late preganancy presents with nausea, RUQ pain, and jaundice. She eventually becomes confused. If acute fatty liver of pregnancy is suspected, what do you expect to see on histologic examination of the liver? What is the treatment of choice?
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Widespread microvesicular steatosis (especially around Zone 3-pericentrally), with little inflammation or hepatocellular necrosis.
Delivery of the baby |
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What hematologic problem is common in acute fatty liver of pregnancy?
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DIC
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A woman in her 3rd trimester of pregnancy presents with jaundice and itching. If cholestasis of pregnancy is suspected, what laboratory findings can you expect? (6 things)
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Elevated Alk Phos (massively), increased GGT, increased 5'-nucleotidase, direct bilirubinemia (but less than 5mg/dL), normal or mildly elevated transaminases, increased bile acids *** (most characteristic)
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What are the typical histological findings in cholestasis of pregnancy?
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dilated canaliculi containing bile plugs, especially in pericentral (zone 3) region
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Name 4 tests that might be undertaken to evaluate "recurrent pregnancy loss:"
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Parental or abortus karyotyping, endometrial biopsy, thyroid function, lupus anticoagulant
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What is luteal phase defect defined as in regards to endometrial biopsy?
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endometrial histology that is 2 or more days discrepant with dates
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3 Clinical applications of Toxicology?
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Drugs of abuse screening, overdose management, therapeutic drug monitoring
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Define half-life:
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The time it takes for the drug concentration to reach 1/2 of the starting amount
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What is first-order kinetics?
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The rate of loss is exponential during drug elimination
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What is steady-state, when speaking of drug metabolism? (conceptually)
After how many doses does this usually occur? |
the amount of drug leaving the body equals the drug entering the body.
Typically reached after 5 doses given at an interval of 1 half-life each. |
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When do the peak and trough of drug dosages occur?
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Peak: soon after a dose (typically)
Trough: just before a dose |
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What is the most common thing that circulating drugs are bound to?
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Albumin
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Which part is the active component of the drug, free or bound?
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Free
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Increasing the amount of a protein that binds drugs into the circulation will do what to a drug's availability?
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Less free drug is available, and thus may have a weaker effect than anticipated for a dose
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A patient is taking Drug A, a drug with a narrow therapeutic window. He is prescribed a new Drug B. Three days later, he is admitted to the ER with toxicity of Drug A. What could be a mechanism involved in this that includes binding proteins?
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Likely Drug B displaced Drug A off of a binding protein, increasing the amount of Drug A available
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Which drugs remain tightly confined in the vascular space, lipophobic (aka-hydrophilic) or lipophilic (hydrophobic)?
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Lipophobic/hydrophilic
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The degree to which a drug can distribute into various body tissues (vasculature, adipose tissue, interstitium, etc) is defined as its:
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Volume of distribution
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What equation can calculate a drugs volume of distribution?
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Vd=D/C
where D= dose and C=resulting measured plasma concentration |
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What is the most typical specimen received for drug screening (drugs of abuse)?
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Urine
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Urine drug of abuse screens have a low or high sensitivity?
Low or high specificity? |
High sensitivity
Low specificity |
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What method is most frequently employed in drug of abuse screens?
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Immunoassay
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Why does every positive drug of abuse screen require confirmation?
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False positives due to cross-reactivity can occur
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What methods are typically used for confirmatory testing for a positive drug of abuse screen?
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Mass spectrometry and or gas chromatography
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What is "chain of custody?"
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A method insuring that a specimen that will have potential consequences is under control of someone or in locked storage at all times.
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Name 7 different checks that can be performed to evaluate a urine sample for adulteration:
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Color, Odor, Temperature, pH, Specific gravity, creatinine, nitrite
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What is the half-life of Cocaine?
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1 hour
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How long is cocaine detectable in testing?
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24-72 hours
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Key metabolites of cocaine:
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benzoyl ecgonine methyl ester
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What is the half-life of heroin?
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3 minutes
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How long is heroin detectable in testing?
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72 hours
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Key metabolite of heroin:
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6-acetyl morphine
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What is the half-life of amphetamine?
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30 minutes
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How long are amphetamines detectable in testing?
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72 hours
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2 key metabolites of amphetamines:
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norepinephrine and phenylacetone
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What is the half-life of PCP?
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30 minutes
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How long is PCP detectable in testing?
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72 hours
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2 metabolites of PCP:
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hyroxylated and gluconarated PCP
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What is the half-life of cannabis?
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8 hours (wow!)
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How long is cannabis detectable in testing?
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Weeks
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What is the key metabolite of cannabis?
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delta-9-THC-COOH
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What is physiologic basis of chest pain in cocaine users?
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Vasoconstriction with concurrent increased rate and blood pressure
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What happens to the specificity of myoglobin, CK-MB, and troponin I in cocaine-induced myocardial infarction?
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CK-MB and myoglobin specificity decrease due to skeletal muscle effects, but Troponin I stays the same
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Acute intoxication with opiates can lead to: (name 5 symptoms)
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Sedation, pinpoint pupils, constipation, bradycardia, and hypotension (also respiratory depression)
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What drug is commonly used to counteract opioid intoxication?
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Narcan (Naloxone) (also Nalmefene) are synthetic opioid antagonists that counteract the opioid effects
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Withdrawl from opiates commonly causes the following: (name 7 symptoms)
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increased lacrimation, rhinorrhea, diaphoresis, dilated pupils, tachycardia, irritability, restlessness
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What is methadone?
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A long-acting opioid that can be used to help withdrawl symptoms (less high, more sustained treatment of all withdrawl symptoms)
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What is clonidine's role in opioid withdrawl?
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It does not interact with the opiod receptors (like methadone does) but counteracts the symptoms through other mechanisms.
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Why does propoxyphene cause more symptoms than other opioids?
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It (and its metabolite) have a interference with calcium channels of the heart, very similar to quinidine.
Can cause cardiac conduction abnormalities and even seizures |
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How do barbituates act on the CNS?
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They facilitate GABA (a depressant) effect in the CNS, especially in the medulla
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How do amphetamines (and methamphetamines) act on the CNS?
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Mediate release of dopamine
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What are long-term effects of meth and amphetamine use that are related to their mechanism of action?
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The release of dopamine eventually depletes and destroys the dopamine secreting cells of the substantia nigra and cause Parkinsonian syndrome (it's irreversible!)
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How does phencyclidine (PCP) act on the CNS?
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It acts on blocking catecholamine re-uptake
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What unique symptomatology often occurs with PCP use? (2 things)
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Its especially known for psychiatric effects. Horizontal nystagmus is very often seen.
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What other lab testing, besides a drug screen, must be carried out in those individuals suspected of having PCP intoxication?
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Glucose monitoring: often can cause hypoglycemia
CK and BUN: can cause rhabdomyolysis |
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At what blood alcohol level does coma/death occur?
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>0.4 % BAC
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Outline the steps of alcohol metabolism:
In what organ does this occur? |
Liver
Ethanol metabolized by alcohol dehydrogenase to acetaldehyde. Acetaldehyde is then converted by aldehyde dehydrogenase to acetic acid |
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What type of tube should whole blood for alcohol testing be submitted in?
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Sodium fluoride and potassium oxalate will prevent increases (from fermentation) or decreases in the level
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What methodology is used for analyzing blood for alcohol content?
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Enzymatic method utilizing alcohol dehydrogenase
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What is the short-coming is using an alcohol dehydrogenase method for analyzing blood alcohol content?
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Only measures ethanol, will not pick up methanol
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What principle is used for analyzing breath alcohol?
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Since blood alcohol diffuses across alveolar septa and is excreted in expiration, the level can be measured in breath
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What is the ratio of blood:breath alcohol?
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2100:1
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What liver function test is often increased in chronic alcohol users?
When does it increase? |
GGT (gamma glutamyl transferase)
>4 drinks per day for more than 4 weeks 4 weeks of abstinence to decrease |
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Wat is CDT? What is it being used for evaluating?
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Carbohydrate deficient transferrin: being investigated as a marker of heavy alcohol consumption. More specific than GGT, at least as sensitive as GGT. Raises sooner than GGT.
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Which 2 populations may not be as easy to monitor with CDT levels? Why?
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Women: they have naturally higher CDT, and it doesn't rise as much with alcohol.
Those with chronic liver disease--they have elevated levels of CDT without drinking being involved |
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What RBC parameter measured by a CBC (or peripheral smear review!) is elevated with heavy alcohol consumption?
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MCV
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How is anion gap calculated?
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Sodium - (Chloride + BIcarb) = anion gap
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When is an increase in anion gap significant?
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20 mEq/L or higher is significant
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What is an important cause of decreased anion gap?
Why is this important? |
Hypoalbuminemia. For every 1gram decrease, there is a 2.5 mEq decrease in anion gap.
Important because this could "mask" an increase in anion gap! |
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An increase in anion gap can lead typically to acidosis or alkalosis?
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Acidosis
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Numerous toxins cause anion gap metabolic acidosis: (listed are 12)
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Acetominophen, Salicylates, ascorbate, hydrogen sulfide, ethylene glycol, methanol, ethanol, formaldehyde, carbon monoxide, nitroprusside, epinephrine, paraldehyde
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What is a toxidrome?
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A set of symptoms that can suggest a particular agent or group of agents have been ingested
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