Unit X: Uric Acid Determination Flashcards
(91 cards)
1
Q
What does NPNs stand for?
A
Non-Protein Nitrogenous Compounds
2
Q
Organ in trouble when there is elevation of NPNs in the bloodstream
A
Kidneys
3
Q
- The only NPN that tells that the liver is in trouble if it is elevated in the bloodstream
A
Ammonia
4
Q
- It is a toxic byproduct that needs to be converted to urea for detoxification
A
Ammonia
5
Q
NPN that it not considered as a waste product
A
Amino Acid
6
Q
4 NPNs that are waste products and the body needs to get rid off
A
Urea
Uric Acid
Creatinine
Ammonia
7
Q
End product of purine catabolism
A
Uric Acid
8
Q
End product of protein catabolism
A
Urea
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
10
Q
(T/F)
Uric Acid is produced in the kidneys
A
False
UA is produced in the liver
11
Q
What is the precursor of Uric Acid?
A
Xanthine
12
Q
Xanthine is acted upon by _______ ______
A
Xanthine oxidase
13
Q
(T/F)
Xanthine is to be converted to Uric Acid
A
True
14
Q
T/F
Uric Acid is the product of the catabolism of:
Exogenous (dietary) and Endogenous purine nucleosides
A
True
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
16
Q
How many percentage of most uric acids are excreted?
A
1% excreted
17
Q
Purines from the breakdown of ingested nucleic acids or tissue detruction are converted into uric acid, primarily in the _______(organ)
A
Liver
18
Q
(T/F)
Decrease in serum uric acid is uncommon
A
True
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
20
Q
The deposit of urate crystals in the joints and tissue are called
A
Tophi
21
Q
When tophi is present, it induces an intense inflammatory response known as ____
A
Gout
22
Q
This can occur in urine when uric acid concentrations is abnormally high
A
Urate crystals
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
24
Q
It is where uric acid is produced.
(Where in the organ?)
A
Liver -> Lobules -> Hepatocytes
25
-Cells that make up the lobules
-It is where uric acid is produced
Hepatocytes
26
From the hepatocytes, where do most of the uric acids go as waste products?
To the bloodstream to be disposed properly
27
Part of the kidney that reabsorbs 90% of the uric acid to be
Proximal convoluted tubule
28
Part of the kidney that secretes uric acid to be **thrown in the URINE**
Glomerulus (Distal convoluted tubule)
29
What ages of Males are commonly affected with Gout?
Females in what state are commonly affected with Gout?
Males age 30-50
Females in menopausal
30
If the physician is requesting for uric acid, it means they are suspecting that the patient has ______
Inflammatory condition in the joints: Gout
31
Uric acid is an important analyte utilized by the physician to monitor patients undergoing ________.
Because of the increased breakdown cells -> nucleic acids -> uric acid
Chemotherapy
32
33
(T/F)
Cancer cells in terms of nucleus-cytoplasm ratio is very low
False.
Very high ratio of N:C
34
(T/F)
Cancer drugs disintegrate cancer cell nucleus that contains DNA made up of pyrimidines and purines which are metabolic precursors of uric acid
True
35
If the chemotherapy is effective, the concentration of the uric acid in the plasma will be low.
False.
Chemotherapy is effective when plasma uric acid becomes high
36
T/F
High uric acid is seen in megaloblastic anemia
True
37
This disease causes DECREASED🔻 concentration of uric acid because the **cells that produces** uric acid are destroyed
Liver Disease
38
This disease causes DECREASED🔻 concentration of Uric Acid because there will be **no reabsorption** of uric acid
Renal Failure/Tubular Failure
39
Historical method for the determinatoin of uric acid
Conversion of uric acid to allantoin
40
Other name for the Spectrophotometric Assay
Blauch and Koch
41
In the spectrophotometric assay, we measure the reaction at an absorbance of ____ nm
293 nm
Tunay Tree 🌳
42
(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.
True
43
In the spectrophotometric assay, give an example of the sources of error
-Presence of protein (false increase)
-Hemoglobin and Xanthine (false decrease)
44
Presence of protein causes false-____ due to high background absorbance
False-increase
Protein = HIGH bg. absorbance = false INCREASE
45
Hemoglobin and Xanthine causes false-____ due to negative interference
False Decrease
HbX = NEGATIVE interference = false DECREASE
46
(T/F)
Uric acid has a maximum absorbance of 293 nm,
Allantoin has none
True
47
(T/F)
Decrease in absorbance is directly proportional to the concentration of uric acid
True
↓Abs : Uric Acid Concentration
48
The enzymatic measurement of uric acid employs the following principle:
(1st reaction): In the presence of ____(enzyme) the uric acid is converted into _____ and _____
In the presence of **Uricase**, the uric acid is converted into **Allantoin** and **Hydrogen peroxide**
49
This enzyme speeds up/hastens the oxidation of uric acid to allantoin
Uricase
50
Uric Acid is readily oxidized to **allantoin** and therefore can function as a/an ________ agent in chemical reaction
Reducing or Oxidizing?
**REDUCING** agent
51
# **
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
**Red-violet** quinoneimine dye
52
Which is the indicator in the coupled enzymatic reaction?
a. 4-AAP
b. EHSPT
c. quinoneimine
b. EHSPT
53
Which is the colored product in the coupled enzymatic reaction?
a. 4-AAP
b. EHSPT
c. quinoneimine
c. quinoneimine
54
(T/F)
The *source of error* in the coupled enzymatic reaction method are **reducing agents**
True
55
Examples of a reducing agent that might cause an error in the coupled enzymatic reaction method
-High bilirubin (False-positive)
- Ascorbic acid or Vitamin C
56
High Bilirubin = False-____ result
false-positive
57
This enzyme reduces hydrogen peroxide into oxygen and water
Peroxidase
58
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)
1. Uricase
2. Peroxidase
59
(T/F)
Enzymatic assays are more specific than Chemical Assays
TRUE.
Enzymatic > Chemical
60
Quinoneimine uses a light with a wavelength of ____ nm
540 nm
(same as for Hb determination)
61
What is the relationship of proportion between Quinoneimine conc. with Uric acid?
Directly proportional
Quinoneimine↑ = Uric Acid
62
In higher primates, such as human and apes, this is the final breakdown product of purine catabolism
Uric Acid
63
Most other mammals (not humans and apes), have the ability to catabolize purines into ________
Allantoin
64
Who is more water-soluble?
Uric Acid or Allantoin?
Allantoin is a more water-soluble end product
65
This chemical method is the most common method used
Phototungstic Acid (Caraway Method)
66
What is the principle of Cataway Method?
ReDox Reaction
67
This chemical method is non-specific and requires protein removal
Caraway's Method
68
Caraway Method:
Uric acid is oxidized to allantoin anc there is a subsequent reduction of _________acid to _______ _____
Subsequent reduction of **Phototungstic acid** to **Tungsten blue**
69
Blood Uric Acid Normal Ranges:
Male:
Female:
Male: 3.5-7.2 mg/dL
Female: 2.6 - 6 mg/dL
70
Expected Range of Control Normal
CN: 4.53 - 6.13 mg/dL
71
Expected Range of Control Pathologic
CP: 9.27 - 12.55 mg/dL
72
Concentration of the Standard (Cs)
6 mg/dL
73
Other Methods of Measurement:
High Performance Liquid Chromatography (HPLC) typically uses _ _ detection
UV detection
74
What is the proposed candidate reference method for Uric Acid measurement?
IDMS
Isotope Dilution Mass Spectrometry
75
This method detects characteristic fragments following ionization
IDMS
Isotope Dilution Mass Spectrometry
76
This method quantifies uric acid using isotopically labelled compound
IDMS
Isotope Dilution Mass Spectrometry
77
(T/F)
Specimen considerations:
Serum and plasma should be removed immediately from the cells as quickly as possible to prevent dilution from intracellular contents
True
78
(T/F)
Specimen considerations:
Fasting is required for BUA testing
False. Fasting is not required for both BUN and BUA testing
79
Specimen considerations:
Hemolyzed samples causes false-____ level, simply because glutathione is released in your red cells
Hemolyed: False-**decrease**
80
Specimen considerations:
Icteric samples:
Bilirubin causes false-____ or may serve as a negative interference in the reaction, especially in the peroxidase methods
Bilirubin: False-**decrease**
81
(T/F)
Specimen considerations:
Lipemia causes background interference in spectrophotometric analysis
True
82
Uric acid sample is stable in refrigirated temperature for about __-__ days
Stable at ref. temp for about **3-5 days**
83
(T/F)
Specimen considerations:
**Salicylates** and **Thiazides** can cause *FALSE ELEVATION* of uric acid values
True
84
Specimen considerations:
Which tube additives should you avoid due to their inhibiting property against uricase enzymes?
EDTA and Fluoride
85
(T/F)
For plasma samples, you may use Heparin since it is preferred for chemical analysis
True
86
Urine samples should have an ____ pH, because if urine samples are not in that pH, the tendency is your Monosidium urease will precipitate.
Alkaline pH
87
Laboratory Assay Requirements:
Wavelength: _ nm
Optical path: __cm
Temperature: __°C
- this temperature because we used the enzymatic reaction
Laboratory Assay Requirements:
Wavelength: 546 nm
Optical path: 1cm
Temperature: 37°C
88
What is the formula used for the calculation?
_ _ _ _'s _ _ _ Formula
Beer's Law Formula
89
What is the formula?
C= (Abs of sample / Abs of std) (Conc. of Std.)
90
What is the conversion factor from mg/dL to mmol/L
0.0595
~ 0.06
91
