02 URIC ACID

Question 1

Uric acid is the product of catabolism of ___ bases like ___ and ___

Answer 1

purine
adenine & guanine

Question 2

___% of uric acid is reabsorbed in the proximal tubules

Answer 2

98-100

Question 3

___% of uric acid is excreted in the distal tubules

Answer 3

<1

Question 4

Among the excreted uric acid, ___% is excreted renally while ___% is excreted via GI tract

Answer 4

70
30

Question 5

T/F: uric acid is soluble in plasma

Answer 5

F (insoluble)

Question 6

Uric acid exists as monosodium urate at pH ___

Answer 6

7

Question 7

At concentrations ___mg/dL, plasma is saturated and urate crystals may form in the tissues

Answer 7

> 6.8 mg/dL

Question 8

At pH ___, uric acid crystals may form

Answer 8

< 5.75

Question 9

High concentrations of uric acid may cause joints and tissue inflammation, causing ___

Answer 9

gouty arthritis

Question 10

Level of uric acid in hyperuricemia

Answer 10

> 6.0 mg/dL

Question 11

Deposits of crystalline uric acid, causing deformities

Answer 11

Tophi forms

Question 12

Gout appears in male between __ and __ years old and in female after ___

Answer 12

30 & 50
menopausal

Question 13

Treatment for increased nuclear breakdown that inhibits xanthine oxidase

Answer 13

allopurinol (Zytoprim)

Question 14

Hemolytic anemia or megaloblastic anemia causes ___ (increase/decrease) in uric acid concentration

Answer 14

increase

Question 15

If uric acid levels are already high, ___ may be used which oxidizes uric acid

Answer 15

Rasburicase

Question 16

Preeclampsia and lactic acidosis causes ___ (increase/decrease) in uric acid concentration

Answer 16

increase

Question 17

Chronic renal disease causes ___ (increase/decrease) in uric acid concentration

Answer 17

increase

Question 18

T/F: uric acid is not a good indicator of renal function

Answer 18

T

Question 19

X-linked genetic disorder that is caused by the complete deficiency of hypoxanthine-guanine phosphoribosyltransferase

Answer 19

Lesch-Nyhan syndrome

Question 20

Lesch-Nyhan syndrome causes ___ (increase/decrease) in uric acid concentration

Answer 20

increase

Question 21

In Lesch-Nyhan syndrome, lack of this enzyme prevents the reutilization of purine bases in the nucleotide salvage pathway

Answer 21

Hypoxanthine-guanine phosphoribosyltransferase

Question 22

Fanconi syndrome causes ___ (increase/decrease) in uric acid concentration

Answer 22

decrease

Question 23

Chemotherapy with 6-mercaptopurine or azathiopurine causes ___ (increase/decrease) in uric acid concentration

Answer 23

decrease

Question 24

Disorder of reabsorption in the proximal convoluted tubules of the kidney

Answer 24

Fanconi syndrome

Question 25

A nonspecific, chemical method of uric acid determination that requires protein removal

Answer 25

Phosphotungstic acid method

Question 26

Direct redox method of uric acid determination

Answer 26

Caraway method/Henry's method

Question 27

A method of uric acid determination based on oxidation of uric acid in a protein-free filtrate, with subsequent reduction of phosphotungstic acid in alkaline solution

Answer 27

Caraway/Henry's method

Question 28

Interferences that causes a false increase in Caraway method

Answer 28

turbidity aspirin and metabolites acetaminophen caffeine theophylline

Question 29

In iron reduction method of uric acid determination, the ___ is measured

Answer 29

chromophore

Question 30

In the uricase method of uric acid determination, the measurement of the differential absorption of uric acid and allantoin is at what wavelength?

Answer 30

290-293 nm

Question 31

In the uricase method of uric acid determination, Hb and xanthine would cause false ___ (increase/decrease)

Answer 31

decrease

Question 32

T/F: one of the disadvantages of the uricase method is that it requires UV spectrophotometer

Answer 32

T

Question 33

In the coupled enzymatic method of uric acid determination, bilirubin and ascorbate would cause false ___ (increase/decrease)

Answer 33

decrease

Question 34

Samples allowed in uric acid determination

Answer 34

Heparinized plasma Serum Urine

Question 35

T/F: diet may affect uric acid concentration

Answer 35

T

Question 36

Interferences in uric acid determination that may falsely increase the value

Answer 36

Salicylate and thiazides

Question 37

Additives for blood collection that are not allowed for uric acid determination

Answer 37

EDTA Fluoride

Question 38

pH level for urine specimen in uric acid determination

Answer 38

8

Question 39

Normal level of uric acid in males

Answer 39

3.5-7.2 mg/dL

Question 40

Normal level of uric acid in females

Answer 40

2.6-6.0 mg/dL

Question 41

Normal level of uric acid in children

Answer 41

2.0-5.5 mg/dL

Question 42

Normal level of uric acid in adult for 24h urine

Answer 42

250-750 mg/d

Question 43

A chemical method of uric acid determination based on reduction of phosphotungstic acid in alkaline solution to tungsten blue

Answer 43

Caraway method

Question 44

The more specific and more commonly used method of uric acid determination

Answer 44

Enzymatic method

Question 45

An enzymatic method of uric acid determination that measures the h2o2 produced as uric acid that is converted to allantoin

Answer 45

Coupled enzymatic reaction

Question 46

In the coupled enzymatic reaction of uric acid determination, the color produced is ___ proportional to uric acid concentration

Answer 46

directly

Question 47

Uric acid determination: False increase/decrease Hemolysis =

Answer 47

decrease

Question 48

Conversion factor of uric acid from conventional to SI unit

Answer 48

0.0595