BLOOD URIC ACID, BUA LABORATORY DETERMINATIONS (TOPIC 3 NON-PROTEINS)

Question 1

Waste product of purine (nucleic acids) catabolism.

Answer 1

Blood uric acid (BUA)

Question 2

Uric acids are _____ in the blood and ____ in acidic urine.

Answer 2

monosodium urates
uric acid crystals

Question 3

Excreted in the urine but ___ are reabsorbed.

Answer 3

90 %

Question 4

When accumulated in the blood it is deposited in the tissues and joints as crystals.

Answer 4

Blood uric acid (BUA)

Question 5

Purines are also present in foods like

Answer 5

liver,
dried beans,
peas and
Beer.

Question 6

Matabolism of Blood Uric Acid

Answer 6

Purines (Guanine monophosphates)(Adenosine Monophosphates)
[Deamination and phosphorylation to form hypoxanthine]

–> Hypoxanthine or Xanthine
[Xanthine oxidase converts hypoxanthine to uric acid]

–> Uric Acid (water insoluble excreted in the urine)
[In some mammals presence of uricase enzyme converts uric acid to allantoin which is water solluble]

Question 7

BUA is mainly synthesized in the

Answer 7

Liver
Intestines
Muscles
Kidney

Question 8

Majority of BUA are reabsorbed from the kidney due to its;

Answer 8

Antioxidant property
Anti-neurodegenerative property
Anti-helminth activity

Question 9

Uric acid can be measured in

Answer 9

serum, urine and plasma.

Question 10

anticoagulant of choice

Avoid what anticoagulant?

and Specimen considerations

Answer 10

Heparin

Potassium Oxalate

Hemolysed
Lipemic

Question 11

BUA determination (chemical method)

Caraway Method

Answer 11

Reduction of uric acid to tungsten blue by PTA

Uric Acid –(up arrow)Phosphotungstic acid,(down arrow)reduction–> allantoin + CO2+ tungsten blue

NaCO3 is added to improve specificity
Requires protein removal

Question 12

BUA determination (enzymatic method)

Uricase method

Answer 12

Oxidation of uric acid by uricase and addition of H2O2

Uric acid –(Uricase)–> allantoin + CO2 + H2O2

Question 13

BUA determination (enzymatic method)

Coupled enzyme I method

Answer 13

Uric Acid –(Uricase)–> allantoin + CO2 + H2O2

H2O2 + phenol + 4-aminoantipyrine –(Peroxidase)–> quinoneimine dye

Interferences : bilirubin and ascorbic acid
Used in automated machines

Question 14

BUA determination (enzymatic method)

Coupled enzyme II method

Answer 14

Urice Acid –(Uricase)–> allantoin + CO2 + H2O2

H2O2 + ethanol –(catalse)–> H2O + acetaldehyde

Acetaldehyde + NAD –> Acetate + NADH + H+ (340 nm)

Question 15

BUA determination METHOD
Sample diluted with known amount of labeled uric acid, record ratio of 2 isotope

Answer 15

Isotope dilution/mass spectrophotometry

Question 16

BUA determination method that is highly specific

Answer 16

HPLC

Question 17

BUA determination method Measurement of decrease absorbance at 290-293 nm due to destruction of uric acid.

Answer 17

Spectrophotometric

Question 18

BUA normal vallues

Children
Female
Male
Conversion Factor

Answer 18

2-5 mg/dl
2-6
3-7
x 0.059

Question 19

Clinical significance of high level of BUA

Answer 19

Hyperuricemia

Question 20

Overproduction of uric acid and over consumption of food rich in purine, drugs and alcohol.

Answer 20

GOUT

Question 21

Uric acid precipitates as monosodium urates crystals in joints causing pain and inflammation.

Answer 21

GOUT

Question 22

Clinical Significance Predominant in men 40-50 years of age.

Answer 22

GOUT

Question 23

It has been hypothesized that BUA accumulation is cause of enhance reabsorption of uric acid in the kidney and inhibits tubular secretion.

What disease?

Answer 23

von Gierk’s disease

Question 24

Patient under chemotherapy
Due to increase breakdown of cells releasing purines

What are these?

Answer 24

Leukemia
Lymphoma
Multiple Myeloma
Plycythemia vera
Megaloblastic anemia

Question 25

Inherited X-linked disorder.
Absence of hypoxanthine–guanine phosphoribosyl transferase.

Answer 25

Lesch-Nyhan syndrome (inborn error of purine metabolism).

Question 26

have a high risk of developing gout.

Answer 26

T2DM

Question 27

less common
Found in Liver disease
and Fanconi syndrome - renal type aminoaciduria

Answer 27

Hypouricemia