[2S] UNIT 9.2 Uric Acid Determination Flashcards
One of the NPNs present in the bloodstream
Uric Acid
Organ in trouble when there is elevation of NPNs in the bloodstream
Kidneys
Only NPN that tells that the liver is in trouble if it is elevated in the bloodstream
Ammonia
Toxic byproduct that needs to be converted to urea for detoxification
Ammonia
Other NPNs circulating in the plasma
Not considered as waste product
Amino acids
Other NPNs circulating in the plasma
● Waste products
● Body needs to get rid of
Urea, Uric acid, Creatinine, Ammonia
End product of purine catabolism
Uric Acid
End product of protein catabolism
Urea
T/F: Urea is higher compared to creatinine
T
Precursor of uric acid
Xanthine
Where is uric acid produced?
Liver
Xanthine is acted upon by what enzyme and to be converted to?
○ Acted upon by Xanthine oxidase
○ To be converted to uric acid
It is a waste product
Uric Acid
Main product of the catabolism of exogenous (dietary) and endogenous purine nucleosides (Adenine and Guanine)
Uric Acid
T/F: Most uric acids are reabsorbed and 1% is excreted
T
T/F: Decrease in serum uric acid is common
F; uncommon
T/F: Although uric acid measurement may assess kidney function, uric acid is not as reliable as that of urea and creatinine.
T
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
1st organ
Liver
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
■ Cells that make up the lobules
■ It is where uric acid is produced
Hepatocytes
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
Functional unit of the liver
Lobules
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
Very vascular organ riched with blood vessels
Liver
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
In the liver, ______ synthesize the uric acid
Hepatocytes
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
travels in the bloodstream in order for them to be disposed properly
Hepatocytes
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
Urinary bladder → urethra (vary in size)
Inner Medulla
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
This network of blood vessels are connected to the kidneys
Hepatocytes
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
3rd site
Kidney (Outer Cortex)
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
Produce uric acid (waste product) → throw it in the _____
blood
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
Calyxes and Pelvis → Drains in the ureter and urinary bladder
Inner Medulla
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
Functional unit of kidney
Nephron
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
T/F: We can live with only 1 nephron and 1 kidney
F; we cannot live with only 1 nephron
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
Each kidney contains approximately 1 million to ____ nephrons
1.5 million
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
● Found in medulla
● Contains blood vessel
Nephron
HOW IT TRAVELS FROM HEPATOCYTE TO KIDNEYS
● Part of nephron that acts as a filter
● Tuft of capillaries
Glomerulus
Why is it reabsorbed if it is a waste product?
It uses raw material for the synthesis of purines
If the physician is requesting for uric acid, it means he/she is suspecting that the patient has inflammatory condition in the joints
Gout
Effective Chemotherapy = ↑ uric acid _ plasma
↑
CHEMOTHERAPY
More cells destroyed _ uric acid
↑ (megalo & cancer)
● Men age 30-50 years old are more commonly affected
● Females: menopausal
Gout
● Decrease concentration of uric acid
● The cells that produces uric acid are destroyed
Liver Disease
● Decrease concentration of uric acid
● 90% of uric acid is reabsorbed in the proximal convoluted tubule
● There will be no reabsorption of uric acid
Renal / Tubular Failure
Mixture of enzymatic and chemical method
Method of Determination
Measure the reaction at an absorbance of _____
293 nm
Historical method for the determination of uric acid
Conversion of uric acid to allantoin
METHOD OF DETERMINATION
Decrease in absorbance is _____ proportional to the concentration of uric acid
directly
Principle of the reagent used in the experiment:
Uric acid + O2 + 2 H2O2 → allantoin + CO2 + H2O2
Uricase
In the presence of uricase, uric acid is converted to?
allantoin and hydrogen peroxide
Principle of the reagent used in the experiment:
2 H2O2 + 4-AAP + EHSPT → quinoneimine + HCl + 4 H2
Peroxidase
Under catalysis of peroxidase with amino-4-antipyrine (4-AAP) and EHSPT, hydrogen peroxide reacts to give a?
red-violet quinoneimine dye
hasten the oxidation of uric acid to allantoin
Uricase
Quinoneimine uses a light with a wavelength of ___
nm
540
T/F: Concentration of quinoneimine (indicator) is directly proportional to uric acid
T
T/F: ENZYMATIC ASSAYS ARE MORE SPECIFIC
THAN CHEMICAL ASSAYS
T
BUA Main form in Plasma
Monosodium Urate
Principle of Caraway Method
Reduction-Oxidation Reaction
CLINICAL APPLICATIONS
T/F: Confirm diagnosis and monitor treatment of gout
T
CLINICAL APPLICATIONS
T/F: Prevent uric acid nephropathy during chemotherapeutic treatment
T
CLINICAL APPLICATIONS
T/F: Assist in the diagnosis of renal calculi
T
CLINICAL APPLICATIONS
T/F: Assess inherited disorders of pyrimidine metabolism
F; purine
CLINICAL APPLICATIONS
T/F: Detect liver dysfunction
F; kidney
Based on reduction of phosphotungstic acid in alkaline solution to tungsten blue
CHEMICAL: Caraway
In carbonate solution (Na2CO3/OH-):
uric acid + H3PW12O40 + O2 → allantoin + tungsten blue + CO2
CHEMICAL: Caraway
Non-specific and requires protein removal
CHEMICAL: Caraway
● Uses uricase enzyme to catalyze oxidation of uric acid to allantoin
● More specific and more commonly used
Enzymatic Methods
Measures the hydrogen peroxide produced as uric acid is converted to allantoin
ENZYMATIC: Coupled Enzymatic Reaction
Color produced is directly proportional to uric acid
concentration
ENZYMATIC: Coupled Enzymatic Reaction
2 Sources of error in coupled enzymatic reaction
Reducing Agents
- High bilirubin
- Ascorbic acid / Vit C
Measures differentiation absorbance before and after incubation with uricase at 293 nm
ENZYMATIC: Spectrophotometric Assay
Difference is directly proportional to uric acid
concentration
ENZYMATIC: Spectrophotometric Assay
2 Sources of error in spectrophotometric assay
Presence of protein
Hemoglobin & Xanthine
OTHER METHODS
Typically uses UV detection
High Performance Liquid Chromatography (HPLC)
OTHER METHODS
● Proposed candidate reference method
● Detects characteristic fragments following ionization
● Quantifies uric acid using isotopically labeled compound
Isotope Dilution Mass Spectrometry (IDMS)
Specimen used
Heparinized plasma, urine or serum
T/F: Heparin inhibits uricase enzymes
F; EDTA & Fluoride
Uric Acid Reagent Kit
Phosphate buffer (pH 7.0), EHSPT, Amino-4-antipyrine, Uricase, peroxidase, ferrocyanide, sodium azide
ASSAY REQUIREMENTS
● Wavelength:
● Optical path:
● Temperature:
● Read against ________
546 nm
1 cm
37° C
reagent blank
HYPER OR HYPOURICEMIA
Gout
Hyperuricemia
HYPER OR HYPOURICEMIA
Treatment of myeloproliferative disease with cytotoxic drugs
Hyperuricemia
HYPER OR HYPOURICEMIA
Hemolytic and proliferative
processes
Hyperuricemia
HYPER OR HYPOURICEMIA
Purine-rich diet
Hyperuricemia
HYPER OR HYPOURICEMIA
Toxemia of pregnancy
Hyperuricemia
HYPER OR HYPOURICEMIA
Increased tissue catabolism or starvation
Hyperuricemia
HYPER OR HYPOURICEMIA
Lactic acidosis
Hyperuricemia
HYPER OR HYPOURICEMIA
Chronic renal disease
Hyperuricemia
HYPER OR HYPOURICEMIA
Lesch-nyhan syndrome (hypoxanthine guanine phosphoribosyltransferase deficiency)
Hyperuricemia
HYPER OR HYPOURICEMIA
Fructose intolerance (fructose-1-phosphate aldolase deficiency)
Hyperuricemia
HYPER OR HYPOURICEMIA
Drugs and poisons
Hyperuricemia
HYPER OR HYPOURICEMIA
Phosphoribosylpyrophosphate synthetase deficiency
Hyperuricemia
HYPER OR HYPOURICEMIA
Liver disease
Hypouricemia
HYPER OR HYPOURICEMIA
Glycogen storage disease type 1 (glucose-6-phosphate deficiency)
Hyperuricemia
HYPER OR HYPOURICEMIA
Defective tubular reabsorption (Fanconi syndrome)
Hypouricemia
HYPER OR HYPOURICEMIA
Chemotherapy with azathioprine or 6-mercaptopurine
Hypouricemia
HYPER OR HYPOURICEMIA
Overtreatment with allopurinol
Hypouricemia
CONCENTRATION OF STANDARD
Plasma / Serum
6 mg/dL
CONCENTRATION OF STANDARD
Urine
88 mg/dL
Conversion factor of mg to mmol/L
0.0595
REFERENCE RANGE PLASMA / SERUM
Male
a. 3.5-7.2 mg/dL
b. 2.0-5.5 mg/dL
c. 2.6-6.0 mg/dL
d. 250-750 mg/day
a. 3.5-7.2 mg/dL
REFERENCE RANGE PLASMA / SERUM
Female
a. 3.5-7.2 mg/dL
b. 2.0-5.5 mg/dL
c. 2.6-6.0 mg/dL
d. 250-750 mg/day
c. 2.6-6.0 mg/dL
REFERENCE RANGE PLASMA / SERUM
Child
a. 3.5-7.2 mg/dL
b. 2.0-5.5 mg/dL
c. 2.6-6.0 mg/dL
d. 250-750 mg/day
b. 2.0-5.5 mg/dL
REFERENCE RANGE
Urine 24h
250-750 mg/day