Hyperuricaemia and Gout Flashcards Preview

Clinical Biochemistry > Hyperuricaemia and Gout > Flashcards

Flashcards in Hyperuricaemia and Gout Deck (22)
Loading flashcards...
1
Q

What is Urate?

A

salt of Uric acid

with the nitrogenous base belonging to the group of purines

2
Q

How is Urate produced?

A

Uric acid is the end product of purine metabolism in primates
Other purines: Caffine, adenine

3
Q

How is Uric acid excreted?

A

Through the urine

Low concentration in plasma normally

4
Q

What 4 sources make the pool of purine nucleotides?

A
Dietary Purine
Breakdown of tissue nucleotides (Tumour lysis syndrome)
Salvage pathway (HGPRT deficiency)
Endogenous synthesis (Phosphoribosyl pyrophosphate=PRPP)
5
Q

what is the pathway of pool of purine nucleotides?

A

Pool of purine nucleotides—>Free purines—>Uric acid—>Renal failure

6
Q

What level of uric acid is hyperuricaemia?

A
It has to be greater than 0.38nm
caused by an overproduction of uric acid 
or under secretion of uric acid
no gout without crystal depostition
silent without disease
7
Q

How do we diagnose Gout?

A
Physical exam (PE)
Medical history (Hx)
Synovial fluid aspiration
X ray
Blood test
8
Q

Aetiology of gout

A

Urate crystals inside joints causing problems at the extremeties
Macrophages attach crystals but cannot dissolve them
Result:Inflamed and painful joints

9
Q

4 gout stages?

A
  1. High uric acid- No symptoms
  2. Acute flares
  3. Intercritical periods
  4. Advanced gout-Chronic Arthritis
10
Q

Where are purines in the diet come from?

A

The breakdown of ingested nucleic acids

11
Q

Where does purine synthesis occur?

A

Mainly in the liver

12
Q

What occurs in the Salvage pathway for a source of purines?

A

In the salvage pathway it reuses free purine bases
2 main enzymes used:
Adenine phosphoribosyltransferase
Hypoxanthinie Guanine phosphoribosyltransferase (HGPRT)

13
Q

Purines are used for:

A

Nucleic acid synthesis
Metabolic reactions
Purines oxidised to uric acid (urate), firstly transfered to xanthinine then transformed to uric acid

14
Q

Where does the uric acid go?

A

to kidneys,3/4 excreted.
also to gastrointestinal gut, metabolised by bacteria (uricolysis) due to lacking the enzyme uricase (breaks down uric acid)

15
Q

What is Lesh Nyhan Syndrome?

A

x linked recessive disorder
Increased synthesis of purine nucleotides
leading to gout and Hyperuricaemia

16
Q

What is Von Gierke’s disease?

A

Accumulation of G6P

Which is transformed into ribose 5 phophate, promoting gout

17
Q

What other conditions can lead to Hyperuricaemia?

A

Associated with the overproduction of cells:

  • Lymphoma
  • Other solid tumours
  • Cytotoxic tumours
  • Alcohol (lactate build up)
  • Aspirin (inhibits renal secretion)
18
Q

where does 75% of urate travel to?

A

kidney

19
Q

Using drugs can cause what secretion?

A

Renal and tubular secretion

20
Q

Reduced renal clearance of urate can be due to?

A
Volume depletion (not drinking enough)
Diuretics
Low doses of salicylates (reduces distal tuble secretion)
21
Q

Gout therapies?

A

1.Anti inflammatory drugs (NSAIDs)
2.Increased renal clearance (probenccid)
3.Xanthine oxidase inhibitor (Allopurinal)
Major factor is renal clearance by kidney

22
Q

What does renal failure cause?

A

Renal stones

raised plasma urate