U4 LEC: NPNs: URIC ACID (PT. 1) Flashcards
Product of catabolism of purine bases
Uric Acid
catabolism also happens in the liver
Purine bases
Adenine, Guanine
Readily filtered by?
glomerulus
Uric acid undergoes?
reabsorption and secretion
____% reabsorbed in the _________
98-100, proximal convoluted tubules
_____% excreted in the _________
<1%, distal tubules
Renal excretion
70%
GI excretion
30%
Relatively insoluble in plasma as _______ at _______
monosodium urate, pH 7.0
At what concentrations does plasma become saturated and may form urate crystals in the tissues?
> 6.8 mg/dL
At what pH does uric acid crystals form?
< 5.75 (acidic urine)
Where does monosodium urate crystals deposit into?
tissues and joints
Where do you see uric acid crystals in pH <5.75?
acidic urine
The accumulation of high concentrations of crystals is called?
Tophi
The inflammation after accumulation in joints and tissues is called?
gouty arthritis
Gout has _____ uric acid, saturated plasma
increased
Inflammation can also lead to?
edema (swelling / pamamanas due to liquid)
Method of reliving Gouty Arthritis
use 50-100mL syringe to aspirate synovial fluid from the knee
Clinical applications of Uric Acid
- confirm diagnosis and monitor treatment of gout
- assess and prevent uric acid nephropathy during chemotherapeutic management
- assess inherited disorders of purine metabolism
- detect kidney dysfunction
- assist in the diagnosis of renal calculi
Clinical Application
Confirm diagnosis and monitor treatment of?
gout
This refers to uric acid in blood.
Monosodium urate
Clinical Application
Assess and prevent uric acid nephropathy during?
chemotherapeutic management
T/F: In chemotherapy, there is increase in the uric acid, and decreased WBC.
True
Cell lysis > kakalat nucleic acids > high purines
Clinical Application
Assess inherited disorders of?
purine metabolism
Clinical Application
Detect?
kidney dysfunction
98% is reabsorbed dapat by the kidneys so UA can be a marker
Clinical Application
Assist in the diagnosis of?
renal calculi
T/F: Uric acid can form renal calculis.
True
Most common kidney stone
Calcium Oxalate (CaOx)
Calcium Oxalate can be seen in conditions of?
- Chronic UTI
- Parahyperthyroidism (production of excessive calcium)
Hyperuricemia
> 6.0 mg/dL
Gout is present in males between?
30 to 50 yrs of age
Gout is present in females after?
menopausal
Normal value of UA
until 7.2
pero dapat daw di ka na umabot dito !
Food rich in purines
- street foods (laman loob; liver, isaw)
- beer
- red meat
- dark meat of fish
- monggo
Pain and inflammation of joints are caused by?
precipitation of sodium urates
Hyperuricemia is seen in what percentage of patients?
25% to 30%
result of overproduction of uric acid
T/F: You can be hyperuricemic and not have gout.
True
Hyperuricemia can cause?
formation of renal calculi
Hyperuricemia can also cause?
increased nuclear breakdown
Increased nuclear breakdown
seen in patients undergoing chemotherapy for?
- leukemia
- lymphoma
- multiple myeloma
- polycythemia
Increased nuclear breakdown
UA monitoring is done to avoid?
nephrotoxicity and renal calculi
Increased nuclear breakdown
Treatment
Allopurinol
Increased nuclear breakdown
Allopurinol inhibits or attacks what enzyme?
Xanthine oxidase
Increased nuclear breakdown
Xanthine Oxidase converts _______ to UA
Hypoxanthine and Xanthine
Increased nuclear breakdown
can also cause?
- Hemolytic/megaloblastic anemia
- Purine-rich diet
UA can also be used to detect?
kidney diseases (impaired filtration and secretion)
T/F: With impaired filtration and secretion, Uric Acid may increase in the blood.
True
T/F: Uric Acid is not a good indicator for renal function.
True
if problema is nasa distal = small amt lang ang nasa urine
This syndrome is an X-linked genetic disorder.
Lesch-Nyhan Syndrome
Lesch-Nyhan Syndrome
only seen in?
males (commonly in male children)
Lesch-Nyhan Syndrome
Absolute/complete deficiency of?
Hypoxanthine-Guanine Phosphoribosyltransferase (HGPT)
Lesch-Nyhan Syndrome
This enzyme is responsible for utilization of purine bases in the nucleotide salvage pathway.
Hypoxanthine-Guanine Phosphoribosyltransferase (HGPT)
Lesch-Nyhan Syndrome
Lack of HGPT prevents reutilization of purine bases in the?
nucleotide salvage pathway
Lesch-Nyhan Syndrome
Consequentially results in?
increased UA in plasma and urine
Lesch-Nyhan Syndrome
Characteristics
- deformities
- neurologic symptoms
- mental retardation
- self mutilation
Lesch-Nyhan Syndrome
____ purine synthesis, _______ degradation product
increasing
Disease Correlation
- mutations on Phosphoribosyl synthetase
- Toxemia of pregnancy (preeclampsia)
- Lactic acidosis
Disease Correlation
Glycogen storage disorder
Type I (Von Gierke)
gluconeogenesis (nucleic acids to energy)
Disease Correlation
Atrophy (tissues will eat theirselves)
Increased tissue catabolism or starvation
Causes of Hyperuricemia
Decreased UA excretion
- Preeclampsia
- Lactic acidosis
Causes of Hypouricemia
Secondary to?
severe liver disease
Causes of Hypouricemia
Defective tubular reabsorption (tuloy tuloy ineexcrete, nasa ihi and di nabalik sa blood)
Fanconi Syndrome
Causes of Hypouricemia
Chemotherapy with?
- 6-mercatopurine
- azathiopurine
Causes of Hypouricemia
6-mercatopurine and azathiopurine inhibits?
de novo purine synthesis
Causes of Hypouricemia
______ of Allopurinol
Overproduction
Reference method for Uric Acid
Isotope dilution mass spectrometry (IDMS)
Direct REDOX Method is called?
Caraway / Henry’s Method
Caraway / Henry’s Method
Utilizes?
Phosphotungstic acid
Caraway / Henry’s Method
Will produce?
Tungsten blue and allantoin
Caraway / Henry’s Method
End product of purine metabolism in lower forms
Allantoin
(UA to Allantoin)
Caraway / Henry’s Method
________ of Uric Acid in PFF
Oxidation
Caraway / Henry’s Method
__________ of Phosphotungstic Acid
Reduction
Caraway / Henry’s Method
False increaase
- turbidity
- aspirin and metabolite
- acetaminophen
- caffeine
- theophylline
Iron Reduction Method
Ferric iron will become?
ferrous iron
Most common method for Uric Acid
Enzymatic Method
Enzymatic Method
Utilizes what enzyme?
Uricase
Uricase Method is also known as?
Blauch and Koch
Uricase Method
Conversion of?
UA to Allantoin
T/F: With the help of Uricase, the amount of UA is proprtional to converted amount of Allantoin
True
Uricase Method
Measurement at?
290-293nm
Uricase Method
more specific but proteins may cause?
high background absorbance
Uricase Method
Negative interference due to?
- Hemoglobin
- Xanthine
This refers to a colorimetric method.
Coupled Enzymatic Method
Coupled Enzymatic Method
After conversion to Allantoin, utilizes?
H2O2 (Peroxide) and indicator dye to produce colored compound
Coupled Enzymatic Method
These may destroy peroxide (wala masyado sasama sa colored compound), may lead to false decrease
- Bilirubin
- Ascorbic acid
Coupled Enzymatic Method
Remedy for Peroxide
Addition of:
- Potassium ferricyanide
- Ascorbate oxidase
IDMS
Detection of?
characteristic fragments after ionization
IDMS
Quantification using?
isotopically labeled compound
Specimen Requirements
- heparinized plasma
- serum
- urine
Specimen Requirements
may affect UA concentration
Diet
T/F: Recent intake of food will not have a significant effect, hence, it is a non fasting test.
True
Specimen Requirements
This should be avoided
Gross lipemia (turbidity causes interference)
Specimen Requirements
May result to low values
Hemolysis with concomitant glutathione release
Specimen Requirements
May increase UA values
- Salicylates
- Thiazides
Specimen Requirements
Serum samples may be refrigerated for?
3 to 5 days
Specimen Requirements
Anticoagulants that should not be used
- EDTA
- Sodium Fluoride
inhibits Uricase
Specimen Requirements
Urine specimen
must be alkalinzed to pH 8(add chemicals)
Conversion Factor
0.06
Reference Values
Male
3.5-7.2 mg/dL (0.21-0.43 mmol/L)
Reference Values
Female
2.6-6.0 mg/dL (0.16-0.36 mmol/L)
Reference Values
Child
2.0-5.5 mg/dL (0.12-0.33 mmol/L)
Reference Values
Adult, Urine 24 h
250-750 mg/d (1.5-4.4 mmol/d)
