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MT6317 > Unit X: Uric Acid Determination > Flashcards

Unit X: Uric Acid Determination Flashcards

1
Q

What does NPNs stand for?

A

Non-Protein Nitrogenous Compounds

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2
Q

Organ in trouble when there is elevation of NPNs in the bloodstream

A

Kidneys

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3
Q
  • The only NPN that tells that the liver is in trouble if it is elevated in the bloodstream
A

Ammonia

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4
Q
  • It is a toxic byproduct that needs to be converted to urea for detoxification
A

Ammonia

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5
Q

NPN that it not considered as a waste product

A

Amino Acid

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6
Q

4 NPNs that are waste products and the body needs to get rid off

A

Urea
Uric Acid
Creatinine
Ammonia

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7
Q

End product of purine catabolism

A

Uric Acid

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8
Q

End product of protein catabolism

A

Urea

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9
Q

T/F

Urea is higher compared to Uric Acid

A

True

Reference Value of BUN:
6-20 mg/dL

Reference Value of BUA:
M: 3.5 -7.2 mg/dL
F: 2.6-6.0 mg/dL

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10
Q

(T/F)
Uric Acid is produced in the kidneys

A

False

UA is produced in the liver

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11
Q

What is the precursor of Uric Acid?

A

Xanthine

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12
Q

Xanthine is acted upon by _______ ______

A

Xanthine oxidase

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13
Q

(T/F)
Xanthine is to be converted to Uric Acid

A

True

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14
Q

T/F

Uric Acid is the product of the catabolism of:
Exogenous (dietary) and Endogenous purine nucleosides

A

True

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15
Q

Elevated uric acid in serum may be caused by:

A
  • Increased purine synthesis
  • Lesch-Nyhan Syndrome
  • Nutritional disturbances
  • Increase nucleic acid turnover in tumor cell proliferation
  • Leukemia
  • Psoriasis
  • Renal failure
  • reactions to cytotoxic drug
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16
Q

How many percentage of most uric acids are excreted?

A

1% excreted

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17
Q

Purines from the breakdown of ingested nucleic acids or tissue detruction are converted into uric acid, primarily in the _______(organ)

A

Liver

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18
Q

(T/F)
Decrease in serum uric acid is uncommon

A

True

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19
Q

(T/F)
Uric Acid is insoluble in plasma

A

True.
This is why in high concentrations, may deposit in the joints and tissues

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20
Q

The deposit of urate crystals in the joints and tissue are called

A

Tophi

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21
Q

When tophi is present, it induces an intense inflammatory response known as ____

A

Gout

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22
Q

This can occur in urine when uric acid concentrations is abnormally high

A

Urate crystals

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23
Q

(T/F)
Although uric acid measurement may assess the kidney function, it is not as reliable as that of urea and creatinine

A

True

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24
Q

It is where uric acid is produced.

(Where in the organ?)

A

Liver -> Lobules -> Hepatocytes

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25
Q

-Cells that make up the lobules
-It is where uric acid is produced

A

Hepatocytes

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26
Q

From the hepatocytes, where do most of the uric acids go as waste products?

A

To the bloodstream to be disposed properly

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27
Q

Part of the kidney that reabsorbs 90% of the uric acid to be

A

Proximal convoluted tubule

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28
Q

Part of the kidney that secretes uric acid to be thrown in the URINE

A

Glomerulus (Distal convoluted tubule)

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29
Q

What ages of Males are commonly affected with Gout?
Females in what state are commonly affected with Gout?

A

Males age 30-50
Females in menopausal

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30
Q

If the physician is requesting for uric acid, it means they are suspecting that the patient has ______

A

Inflammatory condition in the joints: Gout

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31
Q

Uric acid is an important analyte utilized by the physician to monitor patients undergoing ________.

Because of the increased breakdown cells -> nucleic acids -> uric acid

A

Chemotherapy

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32
Q
A
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33
Q

(T/F)
Cancer cells in terms of nucleus-cytoplasm ratio is very low

A

False.
Very high ratio of N:C

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34
Q

(T/F)
Cancer drugs disintegrate cancer cell nucleus that contains DNA made up of pyrimidines and purines which are metabolic precursors of uric acid

A

True

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35
Q

If the chemotherapy is effective, the concentration of the uric acid in the plasma will be low.

A

False.

Chemotherapy is effective when plasma uric acid becomes high

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36
Q

T/F
High uric acid is seen in megaloblastic anemia

A

True

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37
Q

This disease causes DECREASED🔻 concentration of uric acid because the cells that produces uric acid are destroyed

A

Liver Disease

38
Q

This disease causes DECREASED🔻 concentration of Uric Acid because there will be no reabsorption of uric acid

A

Renal Failure/Tubular Failure

39
Q

Historical method for the determinatoin of uric acid

A

Conversion of uric acid to allantoin

40
Q

Other name for the Spectrophotometric Assay

A

Blauch and Koch

41
Q

In the spectrophotometric assay, we measure the reaction at an absorbance of ____ nm

A

293 nm

Tunay Tree 🌳

42
Q

(T/F)

In the spectrophotometric assay,

Since we measure the sample before and after the reagent (uricase enzyme),

The difference of its absorbance is directly proportional to uric acid concentration

Ab1-Ab2 = UA conc.

A

True

43
Q

In the spectrophotometric assay, give an example of the sources of error

A

-Presence of protein (false increase)
-Hemoglobin and Xanthine (false decrease)

44
Q

Presence of protein causes false-____ due to high background absorbance

A

False-increase

Protein = HIGH bg. absorbance = false INCREASE

45
Q

Hemoglobin and Xanthine causes false-____ due to negative interference

A

False Decrease

HbX = NEGATIVE interference = false DECREASE

46
Q

(T/F)
Uric acid has a maximum absorbance of 293 nm,
Allantoin has none

A

True

47
Q

(T/F)

Decrease in absorbance is directly proportional to the concentration of uric acid

A

True

↓Abs : Uric Acid Concentration

48
Q

The enzymatic measurement of uric acid employs the following principle:

(1st reaction): In the presence of ____(enzyme) the uric acid is converted into _____ and _____

A

In the presence of Uricase, the uric acid is converted into Allantoin and Hydrogen peroxide

49
Q

This enzyme speeds up/hastens the oxidation of uric acid to allantoin

A

Uricase

50
Q

Uric Acid is readily oxidized to allantoin and therefore can function as a/an ________ agent in chemical reaction

Reducing or Oxidizing?

A

REDUCING agent

51
Q

**

For the secondary reaction, hydrogen peroxide then reacts under the catalysis of peroxidase (enzyme) with amino-4-antipyrine (4-AAP) and N-Ethyl-N-(2-hydroxy-3-sulfopropyl)-m-toluidine (EHSPT) to give you a ____________(color) quinoneimine dye

A

Red-violet quinoneimine dye

52
Q

Which is the indicator in the coupled enzymatic reaction?

a. 4-AAP
b. EHSPT
c. quinoneimine

A

b. EHSPT

53
Q

Which is the colored product in the coupled enzymatic reaction?

a. 4-AAP
b. EHSPT
c. quinoneimine

A

c. quinoneimine

54
Q

(T/F)

The source of error in the coupled enzymatic reaction method are reducing agents

A

True

55
Q

Examples of a reducing agent that might cause an error in the coupled enzymatic reaction method

A

-High bilirubin (False-positive)
- Ascorbic acid or Vitamin C

56
Q

High Bilirubin = False-____ result

A

false-positive

57
Q

This enzyme reduces hydrogen peroxide into oxygen and water

A

Peroxidase

58
Q

In the coupled enzymatic reaction method,
What is the enzyme used in the first reaction?
What is the enzyme used in the second reaction?

(this is a common board exam question)

A
  1. Uricase
  2. Peroxidase
59
Q

(T/F)
Enzymatic assays are more specific than Chemical Assays

A

TRUE.

Enzymatic > Chemical

60
Q

Quinoneimine uses a light with a wavelength of ____ nm

A

540 nm

(same as for Hb determination)

61
Q

What is the relationship of proportion between Quinoneimine conc. with Uric acid?

A

Directly proportional

Quinoneimine↑ = Uric Acid

62
Q

In higher primates, such as human and apes, this is the final breakdown product of purine catabolism

A

Uric Acid

63
Q

Most other mammals (not humans and apes), have the ability to catabolize purines into ________

A

Allantoin

64
Q

Who is more water-soluble?

Uric Acid or Allantoin?

A

Allantoin is a more water-soluble end product

65
Q

This chemical method is the most common method used

A

Phototungstic Acid (Caraway Method)

66
Q

What is the principle of Cataway Method?

A

ReDox Reaction

67
Q

This chemical method is non-specific and requires protein removal

A

Caraway’s Method

68
Q

Caraway Method:

Uric acid is oxidized to allantoin anc there is a subsequent reduction of _________acid to _______ _____

A

Subsequent reduction of Phototungstic acid to Tungsten blue

69
Q

Blood Uric Acid Normal Ranges:

Male:
Female:

A

Male: 3.5-7.2 mg/dL
Female: 2.6 - 6 mg/dL

70
Q

Expected Range of Control Normal

A

CN: 4.53 - 6.13 mg/dL

71
Q

Expected Range of Control Pathologic

A

CP: 9.27 - 12.55 mg/dL

72
Q

Concentration of the Standard (Cs)

A

6 mg/dL

73
Q

Other Methods of Measurement:

High Performance Liquid Chromatography (HPLC) typically uses _ _ detection

A

UV detection

74
Q

What is the proposed candidate reference method for Uric Acid measurement?

A

IDMS

Isotope Dilution Mass Spectrometry

75
Q

This method detects characteristic fragments following ionization

A

IDMS

Isotope Dilution Mass Spectrometry

76
Q

This method quantifies uric acid using isotopically labelled compound

A

IDMS

Isotope Dilution Mass Spectrometry

77
Q

(T/F)

Specimen considerations:
Serum and plasma should be removed immediately from the cells as quickly as possible to prevent dilution from intracellular contents

A

True

78
Q

(T/F)
Specimen considerations:
Fasting is required for BUA testing

A

False. Fasting is not required for both BUN and BUA testing

79
Q

Specimen considerations:
Hemolyzed samples causes false-____ level, simply because glutathione is released in your red cells

A

Hemolyed: False-decrease

80
Q

Specimen considerations:

Icteric samples:
Bilirubin causes false-____ or may serve as a negative interference in the reaction, especially in the peroxidase methods

A

Bilirubin: False-decrease

81
Q

(T/F)
Specimen considerations:

Lipemia causes background interference in spectrophotometric analysis

A

True

82
Q

Uric acid sample is stable in refrigirated temperature for about __-__ days

A

Stable at ref. temp for about 3-5 days

83
Q

(T/F)
Specimen considerations:

Salicylates and Thiazides can cause FALSE ELEVATION of uric acid values

A

True

84
Q

Specimen considerations:
Which tube additives should you avoid due to their inhibiting property against uricase enzymes?

A

EDTA and Fluoride

85
Q

(T/F)
For plasma samples, you may use Heparin since it is preferred for chemical analysis

A

True

86
Q

Urine samples should have an ____ pH, because if urine samples are not in that pH, the tendency is your Monosidium urease will precipitate.

A

Alkaline pH

87
Q

Laboratory Assay Requirements:
Wavelength: _ nm
Optical path: __cm
Temperature: __°C
- this temperature because we used the enzymatic reaction

A

Laboratory Assay Requirements:
Wavelength: 546 nm
Optical path: 1cm
Temperature: 37°C

88
Q

What is the formula used for the calculation?
_ _ _ _’s _ _ _ Formula

A

Beer’s Law Formula

89
Q

What is the formula?

A

C= (Abs of sample / Abs of std) (Conc. of Std.)

90
Q

What is the conversion factor from mg/dL to mmol/L

A

0.0595

~ 0.06

91
Q
A

MT6317 (2 decks)

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