Exam 5 Flashcards
Which fractions of bilirubin are increased in a hemolytic disorder?
unconjugated and total bilirubin
Which fraction of bilirubin might be expected to be increased in a hepatic disorder?
conjugated
In severe hemolytic jaundice, what would be the expected results for bilirubin and urobilinogen in the urine?
greatly increased urobilinogen
In severe hemolytic jaundice, what would be the expected results for bilirubin and urobilinogen in the feces?
increased urobilin
In severe hemolytic jaundice, what would be the expected results for bilirubin and urobilinogen in the blood?
increased unconjugated bilirubin
Where is urobilinogen formed?
intestines
From what substance is urobilinogen formed?
bilirubin
What is another name for pre hepatic jaundice?
hemolytic
What is another name for post hepatic jaundice?
obstructive
What is another name for unconjugated bilirubin?
indirect
What is another name for conjugated bilirubin?
direct
What is the normal range for total serum bilirubin?
0.2-1.0 mg/dL
What is the normal range of direct bilirubin?
0.0-0.2 mg/dL
Indirect bilirubin is converted to direct bilirubin by conjugation with what?
glucuronic acid
What organ conjugates indirect bilirubin with glucuronic acid to form direct bilirubin?
liver
In what condition is conjugated bilirubin increased?
biliary obstruction
In the Jendrassik-Grof method for bilirubin determination, bilirubin reacts with what reagent to form the purple compound azobilirubin?
diazotized sulfanilic acid
In the Jendrassik-Grof method, what reagent is used to dissolve free bilirubin?
caffeine
In the Evelyn-Malloy method for bilirubin, quantitation of the bilirubin is made my measuring what?
azobilirubin
What reagents are used in the Watson-Schwartz test?
Ehrlich’s reagent, chloroform, N-butanol, sodium acetate
How are porphobilinogen and urobilinogen distinguished from each other since both form a colored compound with p-aminobenzaldehyde?
extraction with chloroform
In the synthesis of heme, what is the direct precursor of porphobilinogen?
Delta ALA
What does ALA in Delta ALA stand for?
aminolevulinic acid
Why is the stool clay-colored in obstructive jaundice?
urobilinogen is absent because of obstruction
To what compound is free bilirubin in the plasma attached?
albumin
What compound is the precursor of uroporphyrin, coproporphyrin, and protoporphyrin?
porphobilinogen
If you know the total bilirubin and the conjugated bilirubin values, how can you determine unconjugated bilirubin?
(total) - (conjugated) = unconjugated
Name the three enzymes involved in heme synthesis that are inhibited by lead.
Delta ALA synthase, porphobilinogen deaminase, ferrochelatase
What is the composition of Ehrlich’s reagent?
diazotized sulfanilic acid
Why is unconjugated bilirubin not found in the urine?
it is not water soluble
What color is urine that contains large amounts of porphyrins?
port wine
Increased bile pigments in the body causes the condition of?
jaundice
In bilirubin methods, total bilirubin develops a color only after what reagent is added?
methyl alcohol
What is the biochemical defect associated with Gilbert’s disease?
defective transport of bilirubin from plasma to liver cells due to reduced activity of the enzyme glucuronyl transferase
What is the most common condition leading to porphyrinuria?
lead poisoning
What normal substance results in the formation of bilirubin when it is broken down?
hemoglobin
What substance is increased in the urine of patients with lead poisoning?
Delta ALA is present
Why is bilirubin unstable once the specimen has been centrifuged?
sensitivity to light
What observation is used to determine urinary porphyrins?
red fluorescence in UV light
What is the basic unit of the structure of porphyrins?
Pyrrole ring
What specific pigment for the color of normal adult feces?
urobilin
What is indicated by the presence of lactic acid in duodenal contents?
acute or chronic gastritis, stomach carcinoma
A sweat chloride is done to check for disorders of what organ?
pancreas
What value for sweat chloride is indicative of cystic fibrosis (CF)?
60 - 200 mEq/L
In what test is an ion-exchange resin used?
Diagnex blue test
In what conditions is the gastric acidity low or absent?
gastric carcinoma
What is the normal pH of gastric juice after stimulation by a test “meal”?
1.5 - 4.0
Duodenal fluid testing is used to diagnose diseases of what organ?
pancreas
What substance is used to induce sweating in sweat chloride analysis?
pilocarpine
In the sweat test, what should be the next step once the electrodes are removed?
remove gauze from arm and weigh it
What is measured by the Diagnex blue test?
free HCl in gastric secretions
What organ, besides the intestinal tract, must be properly functioning to do the Diagnex blue test?
kidney
What is included in the determination of total gastric acidity?
free HCl and combined gastric acidity
What is the composition of Topfer’s reagent
dimethylaminobenzene
Toxic effects from the ingestion of rat poison can occur due to the presence of?
fluoride
Ferric ions are used in the detection of which common drug?
salicylates
What poisons are tested for by the Reinsch test?
arsenic and mercury
Why should you avoid contact with mercury?
absorbed by the skin
What is the sample of choice for most cases of poisoning?
urine
What specimens are preferred in cases of arsenic poisoning?
hair and nails
What level of carboxyhemoglobin can be found in cigarette smokers?
5-15%
What is the purpose of the Trindar reaction?
detection of salicylates
What organ is acetaminophen particularly toxic to?
liver
What enzyme is used to determine ethanol levels?
alcohol dehydrogenase
What is an oncofetal antigen?
protein shown to exist in both embryo fetal tissue and cancer cells
Which tumor marker is used to detect prostatic cancer?
PSA
What tumor markers are used to detect testicular cancer?
beta hCG and AFP
What color is the blood in cases of carbon monoxide poisoning?
bright cherry red
What enzyme is decreased in insecticide poisoning?
pseudocholinesterase
Name the POC test that is useful in the diagnosis of congestive heart failure.
BNP
Name one cardiac marker that is used in the triage cardiac panel.
troponin
What does AFP stand for?
alpha-fetoprotein
What does CEA stand for?
carcinoembryonic antigen
What are the metabolites of epinephrine, norepinephrine, and dopamine?
metanephrine, normetanephrine, VMA, and homovanillic acid (HVA)
In the determination of 17-ketosteroids, what is Zimmerman reagent composed of?
metadinitrobenzene
The renal excretion of sodium which in turn affects serum levels, is controlled by hormones produced where?
adrenal cortex
What is the major hormone responsible for water and electrolyte balance?
aldosterone
Explain the laboratory findings, in regards to TH and TSH, in hyperthyroidism.
increased TH and decreased TSH
Explain the laboratory findings, in regards to TH and TSH, in hypothyroidism.
decreased TH and increased TSH
1-nitroso-2-naphthol is used in the analysis of which amine metabolite?
5-HIAA
What amine is 5-HIAA a metabolite of?
serotonin
Where would you find a pheochromocytoma?
adrenal medulla
Urinary 17-ketosteroids may be elevated in diseases of which endocrine gland?
adrenal gland
Briefly explain the Pisano method.
Acid hydrolysis and absorption on an ion-exchange resin is followed by elution with ammonium hydroxide. Resulting compound is converted to vanillin and reacted with periodate. Colored product of the reaction is measured spectrophotometrically.
Give a brief description of Graves disease.
autoimmune disorder that occurs 6x more frequently in women than men. frequency in general population about 0.04%. antibodies stimulate thyroid by binding to TSH receptors causing diffuse hyperplasia of the thyroid lab results indicate increased T3, T4, FT4I, T3U and decreased or normal TSH. May have exopthalmia and goiter
What is the first and best indicator of hyper- or hypothyroidism?
TSH
What are the catecholamines?
epinephrine, norepinephrine, and dopamine
Which hormones does the thyroid gland produce?
calcitonin, T3, and T4
What is another name for epinephrine?
adrenalin
To which amino acid does the thyroid gland bind inorganic iodide from the plasma?
tyrosine
What is the principle function of the pancreas?
production of insulin and glucagon
Which organ is the major site of steroid metabolism?
liver
Briefly explain Addison’s disease
under function of adrenal cortex, decreased output of aldosterone, epinephrine, cortisol, and some sex hormones; a primary adrenal insufficiency
Cushing’s syndrome is also known as?
hyperadrenalcorticalism
hCG is produced by what?
placenta
How long after conception does hCG being to rise?
1-2 days
What is the function of vasopressin?
stimulates reabsorption of water by the kidney tubules
Where is the hormone epinephrine produced?
adrenal medulla
Argentaffinomas produce elevated levels of what?
serotonin
Briefly explain the function of oxytocin.
stimulate contractions of uterus during delivery and contractions of breast tissue cells to cause milk ejection
What is the site of action of oxytocin?
smooth muscle
What is the site of action of prolactin?
mammary glands
In men, 2/3 of all 17-ketosteroids come from where?
adrenals
In men, 1/3 of all 17-ketosteroids come from where?
testes
name some conditions, other than pregnancy, where you may find increased hCG lvels
hydatidiform mole, choriocarcinoma, testicular tumors
What foods should be excluded from the diet for at least two days prior to collecting a urine specimen for 5-HIAA?
bananas, avocados, pineapple, plums, walnuts, tomatoes, kiwi, and eggplant
How is most plasma thyroxine found?
bound to globulin
What is the chief hormone excreted by the adrenal cortex?
cortisol
The most potent and biologically active estrogen is?
17-beta-estradiol
What is the action of progesterone?
preparation of uterus for ovum implantation
What is the most potent of the biologically active androgens?
testosterone
What is the parent substance in the biosynthesis of all adrenal cortical steroids?
cholesterol
Of the thyroid iodide hormones, which is the most biologically active?
T3
What hormone regulates the rate of thyroid hormone synthesis and secretion?
TSH
Where is TSH produced?
anterior pituitary
Briefly explain the negative feedback mechanism in the relationship between cortisol and ACTH
increased cortisol levels cause the hypothalamus and pituitary to decrease production of CRH and ACTH; decreased ACTH causes adrenal glands to decrease cortisol production
