Purine and Uric Acid Metabolism Flashcards
Describe uric acid
Poorly soluble in plasma
Lower the pH the less soluble it becomes
Uric acid reversible reaction to urate releasing proton
Comes from the breakdown of purines (e.g. A, G)
Name the purines
Adenine
Guanine
Hypoxanthine
Xanthine
What is the source of purines
Diet
Breakdown of nucleotides from tissues
Synthesis in the body
How does uric acid leave the body
Excreted in urine (predominately)
Breakdown in the gut (small amount)
Describe gout
High uric acid levels in the blood cause urate/uric acid crystals to deposit in joint
The crystals cause inflammation, which then causes the swelling, pain and redness
What is uric acid balance
Production/intake vs. excretion
Explain purine metabolism
Purine synthesis + dietary purines + tissue nucleotides = body purine nucleotides
= purines to uric acid (end product) to excretion
What are forms of dietary purines
Meat
Offal - heart, liver and kidney
Seafood - muscles
Fish - herring and sardines
Oatmeal, soya and yeast extracts
Fructose - found in soft drinks
What can lead to reduced excretion
Reduced kidney function
Risk of gout
Metabolic syndrome
- obesity
- raised triglycerides
- raised blood pressure
Coronary heart disease
Diabetes
What are complications of high uric acid
Kidney stones
- urate crystals can form in the kidneys
- cause damage to the kidneys and reduces kidney function
Gout
Gouty tophi - urate crystals deposited in the soft tissue
What does purine metabolism include
De novo synthesis
Recycling pathways
What is uric acid
Metabolic end product of purine metabolism
Define hyperuricemia
Due to over-production or under-excretion of uric acid or due to a combination
What are the most commonly affected joints from gout
Big toe
What are the most commonly affected joints from gout
Big toe
