Toxicology screening platfrom
Immunoassay
Toxicology confirmatory platform
Chromatography
gas= gold standard
Can also do liquid
Antidotes for ethylene glycol poisoning?
Fomepizole
Antidote for acetaminophen poisoning?
Acetylcysteine (to replenish glutathione stores)
How long after ingestion should you wait to get an acetaminophen level?
4 hours…. need to wait for drug to get fully distributed
Elimination of drug is independent of drug concentration
0 order kinetics
Elimination is dependent on drug concentration
first order kinetics
Most common cause of acute liver failure in UK and US?
Acetaminophen poisoning
Nomogram used to monitor acetaminophen poisoning?
Rumack and Matthew nomogram
Hepatotoxicity is rare if the antidote to acetaminophen poisoning is administered with in what time frame?
8 hours
Anhydrosis Mydriasis Flushing Fever Delirium
Anticholinergic Toxidrome
Agent blocks Ach
Common agents: antihistamines, atropine, TCA, parkinson’s drugs, Jimson weed
Diarrhea Urination Miosis Bradycardia Bronchoconstriction Emesis Lacrimation Sweating/salvation
Cholinergic Toxidrome
(ACh inhibitor)
Common agents: organophosphate, insecticides
CNS depression Miosis Respiratory depression Bradycardia Hypotension Decreased bowel sounds Decreased reflexes
Opioid Toxidrome
Treatment for opioid overdose?
Naloxone
CNS depression
Ataxia
Slurred speech
Normal VS
Sedative Hypnotic Toxidrome
Common agents: Barbs and benzos
Agitation Anxiety Tremors Delusions Paranois Tachycardia Seizures HTN Mydriasis Hyperpyrexia DIAPHORESIS
Sympathomimetic Toxidrome
Common agents: Amphetamines, cocaine, ephedrine
*** TO distinguish from Anti-cholinergic toxidrome….. sympathomimetic has sweating!
Anticholinergic = “Dry as a bone”
What antibiotic can cause false positives on the opiod urine screen?
Levofloxacin
Most common cause for UA test cancellation
Sitting at room temp for > 2 hours
When would you use a Clinitest?
To look for reducing sugars
When would you use Ictotest?
Used to confirm presence of bilirubin
What ketones does chemistry pick up in urine?
Acetoacetic acid, and acetone but NOT B-hydroxybutyric acid
Normal urine specific gravilty?
Decreased = more dilute
Normal 1.003- 1.03
Increased = more concentrated
Typical urine pH
4.5 -8
If low pH could be high protein diet, acidosis
If high pH could be after meals, UTI, or bacterial contamination
Can chemistry distinguish between hemoglobinuria and myoglobinuria?
Nope!
Levels of proteinuria
Minimal ~ 50 mg/day
Moderate 50-400 mg/day
Marked > 400 mg/day
Urine strip is more sensitive to which protein?
Albumin
What do urine nitrites indicate?
GRAM NEG bacterial infection
RBCs casts indicate?
Intrinsic renal disease
Fatty casts indicate?
Diagnostic of Nephrotic syndrome
Broad Casts indicate?
Diagnostic of renal failure
Total protein ratio < 0.5
LDH ratio < 0.6
Transudate
Total protein ratio > 0.5
LDH ratio > 0.6
Exudate
At what pH does an effusion need to be drained?
pH < 7.2
Acid can cause more damage, and that pH indicates a definite pathology
SAAG > 1.1 (1.2)
> 1.1 suggests portal HTN
> 1.2 suggests transudate
SAAG < 1.1 (1.2)
< 1.1 suggests malignancy
< 1.2 suggests exudate
Leukocyte levels for joint aspiration
0- 2,000 WBC= Non inflammatory
2,000- 10,000 WBC = inflammatory
> 10,000 WBC = septic joint
Normal opening pressure for CSF
50-180 mmH20
CSF with high predominance of PMN
Bacterial meningitis
CSF with high predominance of lymphocytes
VIRAL but could be fungal or TB
Stool analysis:
Low osmotic gap < 50 mOsm/kg with high fecal sodium
Secretory diarrhea
Stool analysis:
High osmotic gap > 100 mOsm/kg with low sodium
Osmotic diarrhea
Define transudate
fluid accumulation caused by hydrostatic and osmotic pressure across a HEALTHY membrane (CHF, low serum albumin, constrictive pericarditis)
Define exudate
Fluid accumulation caused by MEMBRANE DAMAGE (malignancy, PE, pneumonia, TB, rheum, chylothroax)
What things are evaluated in Light’s Criteria?
Protein
LDH
Can also look at:
Albumin gradient
What are the components of the Framingham Risk Score?
Gives 10 year risk for CVD event
Components: Age Gender smoking Total cholesterol HDL Systolic BP HTN Rx
Friedewald Calculation of LDL-C?
cLDL = [Total Chol] - [HDL Chol] - TG/5
B-48
Chylomicron
Structural
Chylomicrons have all the apolipoproteins except for?
B100 (binds LDL receptor)
B-100
*binds LDL receptor Found on: VLDL IDL LDL
An increase/decrease in Troponin by what percent is clinical significant?
20% (or 1 standard deviation)
What lab should you always get on an acutely decompensated HF patient?
Troponin
Which of the troponins is not cardiac specific?
TnC
Tnl, and Tnt are cardiac specific
Which lab is NOT recommended as part of routine MI work-up, but is continually ordered by physicians?
CK-MB
What process can cause falsely elevated Troponin I, and falsely low Troponin T?
Hemolysis
What part of the Pro-BNP molecule is active with a short half life?
BNP
What part of the Pro-BNP molecule is inactive with a longer half life, and more stable for analytical measurement?
NT-proBNP
When might you see falsely elevated BNP?
In CKD patients, both BNP and NT-proBNP are renally cleared
HBsAg Neg
Anti-HBc Neg
Anti- HBs Neg
Not infected
Not immunized
HBsAg Neg
Anti-HBc Neg
Anti- HBs Pos
Vaccinated
HBsAg Neg
Anti-HBc Pos
Anti-HBs Pos
Infected but cleared now
has seroconverted (no antigen detected)
HBsAg Neg
Anti-HBc Pos
Anti- HBs Neg
Window Period
** Only Anti-HBc will be positive during window period! **
HBsAg Pos
Anti-HBc (IgM) Pos
Anti-HBs Neg
ACUTE infection
(because IgM, and because positive surface antigen without antibody)
**Don’t know if they will seroconvert or not at this point **
HBsAg Pos
Anti HBc (IgM) Neg
Anti HBC (total) Pos
Anti-HBs Neg
Chronic Infection
**virus on board, past acute period, has not yet seroconverted cuz no Anti-HBs **
ALT, AST > AP
Hepatocellular injury, necrosis
AP > ALT or AST
Cholestatic injury
Elevated AP with normal AST/ALT
OR
AP > ALT, AST
Infiltrative (neoplasm, amyloid)
What test is more specific for liver disease? and has a longer half life?
ALT (AST is found in muscle and red cells)
What should you order to see if the elevated Alk Phos is from the liver?
GGT
AST: ALT > 2
AST < 400
Alcoholic hepatitis
What defines chronic hepatits?
> 3 months duration (transaminases around 300)
Benign defect in UDPGT activity
Jaundice when stressed
Gilbert Syndrome
Bronze diabetes
Ferritin > 200
Hereditary Hemochromatosis
Defect in ATP7B
LOW serum ceruloplasmin
Kayser Fleischer Rings
Wilson Disease
Absent UDPGT activity
Crigler-Najjar Type 1
deficient UDPGT
Crigler-Najjar Type 2
What liver diseases should you expect if elevated direct bilirubin?
Dubin Johnson
Rotor’s Syndrome
If ALT is > 5,000 what should you be thinking about?
Acetaminophen, ischemia, or unusual viruses
What is the best test to order for a patient with a history of
gastric bypass who has had vomiting/diarrhea for the past
week and presents to the ED?
A. Plasma thiamine
B. Urinary thiamine
C. Erythrocyte transketolase activity
D. Whole blood thiamine
D
Plasma and urinary thiamine would show recent intake
Limited storage of thiamine, deficiency can occur in 10-21 days with poor intake
45 year old known alcoholic with burning eyes, sore tongue, reduced appetite, ab pain, dull hair, oily skin
Vit Def?
Riboflavin
10 yr old girl with skin eruptions, ataxia, mental changes, diarrhea, hx of hartnup disease
Vit Def?
B3 = Niacin!
Dermatitis, dementia, diarrhea
Found in foods high in tryptan
Burning feet syndrome
Prisoners
B-Pantothenic Acid
Select the best answer to the question. Why do alcoholics
have an increased AST/ALT ratio?
A. The cofactor, PLP, is needed for both AST and ALT enzymes
and usually deficient in alcoholics
B. In alcoholic hepatitis, there is damage to mitochondria which
releases an isoform of AST to increase the concentration
C. Alcoholics have a reduction in ALT due to liver damage
D. All of the above
Answer D
B does contribute the most, but all are true
What vitmain can cause interference with the T4 and TSH assays?
Biotin
Falsely high T4
Falsely low TSH
Folic acid deficiency can lead to.... A. microcytic anemia B. Pellagra C. Neural tube defects in fetuses of pregnant women D. Wernicke-Korsakoff syndrome
Answer C
Megaloblastic anemia
Neuropathy
Neuropsychiatric damage
B12 deficiency
What vitamin can causes labs to find no cholesterol?
High dose vit C
Called the Trinder Reaction, causes falsely low cholesterol in lab assay
Swollen, bruised, bleeding joints, spongy gums, loose teeth, increased risk of CHD and CVA
Vit Deficiency?
Vitamin C
Which fat soluble vitamin is a radical scavenger in
membranes that protects against lipid peroxidation?
A. Vitamin C
B. Vitamin B12
C. Vitamin K
D. Vitamin E
Answer D
When should you test Vit K levels?
If pt has abnormal INR and does NOT respond to Vit K therapy
An 88-year-old woman with a history of chronic
lymphocytic leukemia presented for routine
ophthalmologic examination. She complained of ‘itchy,
burning eyes’ and general visual decline. Her past ocular
history included uneventful bilateral cataract surgery. The
suspected vitamin deficiency is….
A. Vitamin A
B. Vitamin D
C. Vitamin B12
D. folic acid
Answer: A