Blood Urea Nitrogen

Question 0

Proportional to the urea concentration in the sample

Answer 0

Increase of absorbance at 578 nm

Question 1

Reaction wherein ammonium ions react with hypochlorite and salicylate to give a green dye

Answer 1

Modified Berthelot Reaction

Question 2

It is hydrolyzed in the presence of water and urease to produce ammonia and carbon dioxide

Answer 2

Urea

Question 3

Contents of reagent 1

Answer 3

1 Phosphate buffer
2 Sodium salicylate
3 Sodium nitroprusside
4 EDTA
5 Urease

Question 4

Contents of reagent 2

Answer 4

1 Phosphate buffer
2 Sodium hydroxide
3 Sodium hypochlorite

Question 5

Contents of urea standard

Answer 5

1 Urea

2 BUN

Question 6

Reagent stability

Answer 6

1 Expiry date (2-8 Celsius)

Reagent 1
2 6 weeks (2-8 Celsius)
3 10 days (15-25 Celsius)

Reagent 2
4 6 weeks (2-25 Celsius)

Question 7

Serum

Answer 7

1 Plasma may be used except with ammonium heparin
2 Do not use lipemic sera
3 Serum or plasma can be stored for up to 3 days at 4 Celsius

Question 8

Wavelength

Answer 8

590 nm

Question 9

Optical path

Answer 9

1 cm

Question 10

Temperature

Answer 10

1 20-25 Celsius

2 37 Celsius

Question 11

Calculation of the urea nitrogen concentration

Answer 11

Serum/plasma
1 C = 80 x (sample absorbance/standard absorbance) (mg/dL)
2 C = 13.3 x (sample absorbance/standard absorbance) (mmol/L)

Question 12

Reference range

Answer 12

Serum/plasma: 6-20 mg/dL or 2.1-7.1 mmol/L

Question 13

Contents of reagent 2 that are irritants

Answer 13

1 Sodium hydroxide

2 Sodium hypochlorite

Question 14

Preservative

Answer 14

Sodium azide

Question 15

T or F. All anticoagulants can be used

Answer 15

F. Ammonium heparin cannot be used

Question 16

T or F. The test is not influenced by hemoglobin values up to 200 mg/dL and by bilirubin values up to 10 mg/dL

Answer 16

T

Question 17

Linearity

Answer 17

Serum/plasma: up to 400 mg/dL or 66.6 mmol/L

Question 18

Reagent 1 procedure

Answer 18

Mix and incubate for 5 minutes at 20-25 Celsius or 3 minutes at 37 Celsius

Question 19

Reagent 2 procedure

Answer 19

Mix, incubate for 10 minutes at 20-25 Celsius or for 5 minutes at 37 Celsius

Question 20

Time of measurement

Answer 20

Within 60 minutes