Blood Uric Acid

Question 1

BUA is a byproduct of _ catabolism.

Answer 1

purine nucleic acid

Question 2

BUA is produced in the _ and filtered by _.

Answer 2

liver; glomerulus

Question 3

BUA excreted _% in the proximal tubules.

Answer 3

98-100%

Question 4

What is the main form of BUA in plasma?

Answer 4

monosodium urate

Question 5

What are the clinical applications in measures BUA? (5)

Answer 5

1. Confirm diagnosis and monitor treatment of gout
2. Prevent uric acid nephropathy during chemotherapeutic treatment
3. Assess inherited disorders of purine metabolism
4. Detect kidney dysfunction
5. Assist in the diagnosis of renal calculi

Question 6

Blood uric acid is a _ (reducing, oxidizing) agent.

Answer 6

reducing agent.

Question 7

BUA chemical method:

Based on the reduction of phosphotungstic acid in alkaline solution to tungsten blue.

Answer 7

Caraway method

Question 8

BUA chemical method:

Caraway method is _ (nonspecific, specific) and requires protein removal.

Answer 8

nonspecific

Question 9

Fill in the blank:

Uric acid + H3PW12O40 + O2 → ___ + tungsten blue + CO2

Answer 9

allantoin

Question 10

In enzymatic enzyme, what enzyme is use to catalyze oxidation of uric acid to acid?

Answer 10

uricase enzyme

Question 11

T/F:

Enzymatic methods is more specific and commonly used.

Answer 11

T

Question 12

BUA enzymatic methods:

It measures the hydrogen peroxide produced as uric acid is converted to allantoin.
- sources of error: reducing agents (bilirubin and ascorbic acid)

Answer 12

Coupled enzyme reaction

Question 13

BUA enzymatic methods:

The color produced is directly proportional to uric acid concentration.

Answer 13

Coupled enzymatic reaction

Question 14

BUA enzymatic methods:

What is the source of error in Coupled Enzymatic Reaction?

Answer 14

reducing agents (bilirubin and ascorbic acid)

Question 15

BUA enzymatic methods:

Product in the first step of Coupled enzymatic reaction:

Answer 15

allantoin from uric acid

Question 16

BUA enzymatic methods:

Two enzymes used in Coupled enzymatic reaction:

Answer 16

1. Uricase
2. Peroxidase

Question 17

BUA enzymatic methods:

What is the enzyme used in this reaction?

Uric acid + O2 + 2 H2O2 → allantoin + CO2 + H2O2

Answer 17

uricase

Question 18

BUA enzymatic methods:

What is the enzyme used in this reaction?

2 H2O2 + 4-AAP + EHSPT → quinoneimine + HCl + 4 H2

Answer 18

peroxidase

Question 19

BUA enzymatic methods:

It measures differential absorbance before and after incubation with uricase at 293 nm.

Answer 19

Spectrophotometric assay

Question 20

BUA enzymatic methods:

The difference is directly proportional to uric acid concentration.

Answer 20

Spectrophotometric assay

Question 21

BUA enzymatic methods:

What are the sources of error in Spectrophotometric assay?

Answer 21

• Presence of protein
• Hemoglobin
• Xanthine

Question 22

BUA Determination:

This method typically uses UV detection.

Answer 22

High-performance liquid chromatography (HPLC)

Question 23

BUA Determination:

A proposed candidate reference method, detects characteristic fragments following ionization, and quantifies uric acid using isotopically labeled compound.

Answer 23

Isotope Dilution Mass Spectrometry (IDMS)

Question 24

Specific requirements in BUA

What is the sample needed in quick preparation?

Answer 24

serum sample

Question 25

# Specific requirements in BUA Does the patient requires fasting?

Answer 25

No

Question 26

# Specific requirements in BUA Three samples that are rejected in BUA:

Answer 26

1. Hemolysis 2. Lipemia 3. Icteric

Question 27

# Specific requirements in BUA What should we do if the samples are not processed immediately?

Answer 27

refrigerate

Question 28

# Specific requirements in BUA What are the drugs needed to be avoided to prevent the increase values for uric acid?

Answer 28

* Salicylates * Thiazides

Question 29

# Specific requirements in BUA Tubes that should not be used:

Answer 29

1. EDTA 2. Sodium fluoride

Question 30

# Specific requirements in BUA The urine sample must be _ (acidic, alkaline)

Answer 30

alkaline

Question 31

What are the two Uric Acid Reagent Kit?

Answer 31

1. Phosphate buffer (EHSPT, Amino-4-antipyrine, Uricase, peroxidase, ferrocyanide, sodium azide 2. Standard Uric acid: 6 mg/dL or 0.357 mmol/L (may vary depending on manufacturer)

Question 32

# Assay requirements: Wavelength

Answer 32

546 nm

Question 33

# Assay requirements: Optical path

Answer 33

1 cm

Question 34

# Assay requirements: Temperature

Answer 34

37 C

Question 35

# Calculation: Concentration of Standard of Serum/Plasma:

Answer 35

6 mg/dL or 0.357 mmol/L

Question 36

# Calculation: Concentration of Standard of Urine:

Answer 36

88 mg/dL or 5.235 mmol/L

Question 37

# Calculation: Conversion factor from mg/dL to mmol/L:

Answer 37

0.0595

Question 38

Reference range of plasma/serum of male (adult):

Answer 38

3.5-7.2 mg/dL

Question 39

Reference range of plasma/serum of female (adult):

Answer 39

2.6-6.0 mg/dL

Question 40

Reference range of plasma/serum of a child:

Answer 40

2.0-5.5 mg/dL

Question 41

Reference range in 24-hour urine:

Answer 41

250/750 mg/day

Question 42

Clinical significance of Hyperuricemia: (10)

Answer 42

1. Gout 2. Treatment of myeloproliferative disease with cytotoxic drugs 3. Hemolytic and proliferative processes 4. Purine-rich diet 5. Increased tissue catabolism or starvation 6. Toxemia of pregnancy 7. Lactic acidosis 8. Chronic renal disease 9. Drugs and poisons 10. Enzyme deficiencies

Question 43

What are the 4 types of Enzyme Deficiencies in BUA?

Answer 43

1. Lesch-nyhan syndrome (hypoxanthine guanine phosphoribosyltransferase deficiency) 2. Phosphoribosylpyrophosphate synthetase deficiency 3. Glycogen storage disease type 1 (glucose-6-phosphate deficiency) 4. Fructose intolerance (fructose-1-phosphate aldolase deficiency)

Question 44

Clinical significance of Hypouricemia: (4)

Answer 44

1. Liver disease 2. Defective tubular reabsorption (Fanconi syndrome) 3. Chemotherapy with azathioprine or 6-mercaptopurine 4. Overtreatment with allopurinol