bua Flashcards
T/F Elevated levels of NPNs indicate liver problems
F - elevated NPNs generally indicate kidney problems
only NPN that tells the liver is in trouble when elevated in the bloodstream
ammonia
uric acid is produced in the ___ and filtered by the glomerulus
liver
ammonia is the toxic byproduct that needs to be converted to ____ for detoxification
urea
t/f Uric acid is the end product of protein catabolism
F - end product of purine catabolism; urea - end product of protein catabolism
Elevated levels of ammonia in the bloodstream indicate a problem with the ___
Liver
precursor for uric acid
xanthine
enzyme that converts xanthine to uric acid
Xanthine oxidase
Select: Waste products
A) Amino acids
B) Urea
C) Uric acid
D) Creatinine
E) Ammonia
B C D E
t/f Most uric acids are reabsorbed and only about 1% is excreted
t
t/f Uric acid is 98-100% reabsorbed in the distal tubules
f - reabsorbed in the proximal tubules
Select: uric acid form mainly found in plasma
A) Allantoin
B) Monosodium urate
C) Ammonia
B
condition characterized by monosodium urate crystals forming in urine due to abnormally high uric acid concentrations
gout
condition a physician is likely suspecting when requesting a uric acid test due to an inflammatory condition in the joints (arthritis)
gout
t/f Humans and apes can catabolize purines to allantoin just like most mammals
t
gout commonly affects men aged ___
30-50 years old
t/f Females are more commonly affected by gout before menopause
f - more common after menopause
when present in high concentrations, uric acid can deposit in joints and tissues as ___, leading to gout
tophi
treatment that involves monitoring uric acid levels because of its effects on cancer cells
chemotherapy
Select: Cancer cells during chemotherapy
A) They grow larger
B) They disintegrate
C) They stop reproducing
B
Cancer cells have a high nucleus-cytoplasm ratio, meaning they contain much ___.
DNA
Uric acid levels decrease when chemotherapy is effective because fewer cells are destroyed.
f - More cells destroyed leads to higher uric acid levels
t/f Decrease in serum uric acid is a common condition.
f - uncommon
Select: Elevated serum uric acid levels
A) Increased purine synthesis
B) Lesch-Nyhan syndrome
C) Nutritional disturbances
D) Tumor cell proliferation
E) Renal failure
A B C D E
OOO: Elevated serum uric acid levels
A) Psoriasis
B) Leukemia
C) Cytotoxic drugs
D) Fanconi Syndrome
E) Increased nucleic acid turnover
D
Select: High levels of uric acid in the plasma
A) Megaloblastic anemia
B) Hypothyroidism
C) Cancer
A C
organ’s disease that leads to decreased uric acid concentration due to destruction of the cells that produce it
liver disease
reference value for BUN (Blood Urea Nitrogen) is ___ mg/dL.
6-20 mg/dL
t/f uric acid measurement is the most reliable assessment fot kidney function
f - not as reliable as urea and creatinine
occur in urine when uric acid concentrations is abnormally high
Urate crystals
functional unit of the liver
Lobules
_____ are the cells that make up the lobules and are responsible for producing uric acid
hepatocytes
t/f liver is a highly vascular organ, rich with blood vessels
t
Select: Uric acid produced in the hepatocytes
A) It stays in the liver.
B) It is disposed of directly by the liver.
C) It travels through the bloodstream to be disposed of properly.
C
Sequence: Liver to disposal of UA
A) Hepatocytes
B) Bloodstream
C) Kidney
A B C
t/f kidneys are connected to the bloodstream where waste products like uric acid are filtered out
t
functional unit of the kidney is the ___.
nephron
part of the kidney responsible for draining urine into the ureter
calyxes and pelvis
acts as a filter for the blood, removing waste products like uric acid in the nephron
glomerulus
Blood enters the glomerulus through the ___ arteriole and exits through the ___ arteriole.
afferent, efferent
t/f Each kidney contains approximately 1 million to 1.5 million nephrons
t
where is uric acid secreted to be thrown into the urine
distal convoluted tubule
In renal failure or tubular failure, the proximal convoluted tubule fails to reabsorb ___, leading to decreased concentration
uric acid
Uric acid is reabsorbed in the nephron because it is used as raw material for the synthesis of ___
purines
OOO: Part of the nephron
A) Glomerulus
B) Bowman’s capsule
C) Calyxes
calyxes
Sequence: Passage of filtrate in the nephron
A) Proximal convoluted tubule
B) Distal convoluted tubule
C) Collecting ducts
D) Descending loop of Henle
E) Ascending loop of Henl
A D E B C
In renal failure, _____ of uric acid will be reabsorbed
0%
t/f Waste products like uric acid are entirely reabsorbed and not excreted by the kidney
f - most are reabsorbed for purine synthesis, some are excreted
OOO: Increase uric acid levels
A) Gout
B) Liver disease
C) Chemotherapy
B - decrease
Renal failure leads to an increase in uric acid levels because the kidneys reabsorb more of it
f - renal failure leads to decreased reabsorption of uric acid
wavelength used to measure the maximum absorbance of uric acid
293 nm
Uric acid is readily oxidized to ___ in the presence of water, oxygen, and the enzyme uricase
allantoin
conversion of uric acid to ___ is the historical method for determining uric acid.
allantoin
t/f The concentration of allantoin is measured directly to determine uric acid levels
f - Allantoin has no absorbance, uric acid is measured at 293 nm
In the spectrophotometric assay, the difference in absorbance at 293 nm before and after incubation with uricase is directly proportional to ___
Uric acid concentration.
decrease in absorbance is directly proportional to the concentration of ___ in the uric acid determination method
uric acid
enzyme that catalyzes the oxidation of uric acid to allantoin
uricase
t/f : The enzymatic method using uricase is more specific and commonly used than the chemical Caraway method
t
t/f in the coupled enzymatic reaction, the concentration of quinoneimine (colored end product in the uric acid reaction) is inversely proportional to the concentration of uric acid
f - directly proportional
In the presence of uricase, uric acid is converted to allantoin and ___, a reducing agent
hydrogen peroxide (h2o2)
secondary enzyme responsible for catalyzing the reaction between hydrogen peroxide and amino-4-antipyrine (4-AAP) to form quinoneimine
peroxidase
reagent used to convert hydrogen peroxide into oxygen and water in the enzymatic method
peroxidase
wavelength used to measure the concentration of quinoneimine in the uric acid assay
540 nm
OOO: Byproduct of the reaction involving uricase
A) Allantoin
B) Quinoneimine
C) CO2
B - from peroxidase-catalyzed rxn
t/f Enzymatic assays are less specific than chemical assays for uric acid determination
f - more specific
The chemical method for uric acid determination uses phosphotungstic acid, which is reduced to ___ during the process.
tungsten blue
most common chemical method for uric acid determination
Phosphotungstic Acid Method (Caraway Method)
In the Caraway method, uric acid is oxidized to ___, and phosphotungstic acid is reduced in alkaline solution to tungsten blue.
allantoin
t/f Caraway method is highly specific and does not require protein removal.
f - non-specific; requires protein removal
t/f : High levels of ascorbic acid (Vitamin C) can cause a false increase in uric acid concentration in the enzymatic method.
f - false decrease
formula for calculating the concentration of the unknown (Cu)
Cu = (Au / As) x Cs
Calculate: : If the absorbance of the unknown (Au) is 0.8, the absorbance of the standard (As) is 1.0, and the concentration of the standard (Cs) is 6 mg/dL, calculate the concentration of the unknown (Cu)
Cu = (0.8 / 1.0) x 6 = 4.8 mg/dL.
normal range of uric acid in males
3.5-7.2 mg/dL
normal range of uric acid in females
2.6-6.0 mg/dL
principle used in the Caraway method for uric acid determination
Reduction-Oxidation reaction
Under catalysis of peroxidase with amino-4-antipyrine (4-AAP) and EHSPT, hydrogen peroxide reacts to give a ____ quinoneimine dye.
red-violet
Monosodium urates are insoluble at pH __, causing them to form crystals that may precipitate in tissues.
7
t/f Uric acid nephropathy can occur during chemotherapy because of the selective destruction of tumor cells only.
F - chemotherapy causes non-selective destruction of both tumor and normal cells
OOO: Clinical application of blood uric acid determination
A) Confirming the diagnosis of gout
B) Monitoring liver enzyme levels
C) Detecting kidney dysfunction
B
OOO: Conditions that blood uric acid determination can help assess
A) Inherited disorders of purine metabolism
B) Diabetes mellitus
C) Renal calculi (kidney stones)
B
During chemotherapy, increased destruction of tumor and normal cells leads to ____ levels of uric acid in the blood.
increased
t/f Allantoin is more water-soluble than uric acid and can easily be excreted from the body
t
t/f uric acid can be readily oxidized to allantoin, and the level of allantoin can be measured in the system for determining uric acid levels
t
OOO: Source of error in the coupled enzymatic reaction for uric acid determination
A) High bilirubin
B) Ascorbic acid
C) Albumin
C
proposed as a candidate reference method for uric acid quantification, involving isotopically labeled compounds
Isotope Dilution Mass Spectrometry (IDMS)
OOO: Error source in spectrophotometric assays for uric acid
A) Hemoglobin
B) Protein
C) Glucose
C
High-performance liquid chromatography (HPLC) typically uses ___ detection for uric acid quantification
uv detection
t/f Serum and plasma samples for uric acid determination should be left in contact with cells for a long time to allow nucleic acids to settle.
F - should be removed immediately to prevent dilution from intracellular contents
sample type should be avoided because of its potential to cause a false decrease in uric acid levels due to the release of glutathione
Hemolyzed samples
___ is a powerful antioxidant released from red blood cells in hemolyzed samples, which interferes with peroxidase methods.
glutathione
OOO: Background interference in spectrophotometric analysis for uric acid
A) Hemolysis
B) Lipemia
C) Bilirubin
A
bilirubin in ____ samples causes false ____ or
may serve as a negative interference in the reaction, especially in the peroxidase methods
icteric; decrease
t/f recent meal have significant effects on uric acid levels, and fasting is necessary for accurate measurement
f - no significant effect on uric acid levels, and fasting is not required
uric acid samples are stable for about ___ days when refrigerated.
3-5 days
Select: Avoided anticoagulant for uric acid determination because it inhibits uricase enzymes
A) EDTA
B) Heparin
C) Lithium
D) Fluoride
A D
t/f urine samples for uric acid determination must be kept alkaline to prevent the precipitation of monosodium urate
T
additives cause false elevation of uric acid values and should be avoided before testing
Salicylates and thiazides
most commonly preferred anticoagulant for plasma samples in uric acid determination is ___
heparin
OOO: reagent used in the Uric Acid Reagent Kit
A) Amino-4-antipyrine
B) Sodium azide
C) Potassium permanganate
D) Uricase
E) Peroxidase
F) Ferrocyanide
G) Phosphate Buffer (ph 7)
C
t/f If urine samples are acidic, monosodium urate will precipitate, making uric acid analysis difficult.
t
standard uric acid concentration used in the Uric Acid Reagent Kit is typically ___ mg/dL or ___ mmol/L
6 mg/dL or 0.357 mmol/L
In the uric acid determination, the reagents are already prepared and ready-made, unlike in ___ where you need to mix R1 and R2.
urea determination
t/f during the procedure, you deliver the reagent first before the sample to ensure accurate measurement.
f - sample first
OOO: Part of the procedure for the uric acid test
A) Mix the solution by inverting the tubes 2-3 times
B) Start the incubation immediately
C) Pipet reagent into the sample first
C
correct wavelength for the uric acid assay
546 nm
t/f optical path length required for the uric acid assay is 1 cm
t
For the uric acid assay, the temperature should be set to ___ because the reaction is enzymatic
37 C
conversion factor from mg/dL to mmol/L for uric acid
0.0595
OOO: Reference range for blood uric acid
A) Male: 3.5-7.2 mg/dL
B) Female: 2.6-6.0 mg/dL
C) Child: 1.5-3.5 mg/dL
C - must be 2.0-5.5 mg/dL
reference range for 24-hour urine uric acid is ____
250-750 mg/day
According to the international unit (SI), the reference range for uric acid in males is ___ mmol/L.
0.21-0.43 mmol/L.
treatment of myeloproliferative disease with cytotoxic drugs may increase uric acid levels. One such drug is ___, which inhibits the enzyme xanthine oxidase
Allopurinol
t/f hemolytic processes do not affect uric acid levels since nucleic acids are not released from the cells.
f - nucleic acids are released during hemolysis, increasing uric acid
OOO: Increased uric acid levels
A) Starvation
B) Purine-rich diet
C) Hypoxanthine
C
condition during pregnancy where there is a decrease in uric acid excretion due to competition for renal tubule binding sites
pre-eclampsia
enzyme deficiency that causes an orange sand-like precipitate in newborns’ urine (orange sand diaper syndrome)
Hypoxanthine guanine phosphoribosyltransferase deficiency (Lesch-Nyhan syndrome)
In glycogen storage disease type 1, a deficiency of ___ causes an increase in uric acid due to excessive production of lactate and triglycerides.
Glucose-6-phosphate dehydrogenase
t/f Chronic renal disease leads to decreased uric acid excretion, resulting in higher plasma uric acid levels
t
OOO: Secondary increase in uric acid due to lactate and triglycerides competing for renal excretion
A) Fanconi syndrome
B) Fructose intolerance
C) Glycogen storage disease type 1
A) Fanconi syndrome - involves defective tubular reabsorption of uric acid in PCT
___ is the inhibitor of de novo purine synthesis, which can lead to hyperuricemia during chemotherapy
Azathioprine or 6-mercaptopurine
t/f Overtreatment with allopurinol causes hypouricemia by inhibiting uric acid production
t
condition in which the proximal convoluted tubules fail to reabsorb uric acid, leading to its excessive release in urine, is called ___
fanconi syndrome
OOO: Hypouricemia
A) Liver disease
B) Fanconi syndrome
C) Increased purine synthesis
C - hyperuricemia
When there is liver malfunction, there would be a ______ production of uric acid due to reduced function of hepatocytes
decreased
Select: hyperuricemia
A) Toxemia of pregnancy
B) Fanconi syndrome
C) Overtreatment with allopurinol
D) Chronic renal disease
A D
