Hyperuricaemia

Question 1

What are the main pathways for the fate of uric acid in the body?

Answer 1

(1) Renal excretion
(2) Intestinal uricolysis by bacteria
(3) Loss through kidneys
(4) Excretion of dietary purines

Question 2

Uric acid accumulates in the plasma when GFR ≤ ________mL/min.

Answer 2

20

Question 3

What percentage of uric acid is broken down by intestinal bacteria, and into what substances?

Answer 3

25% of uric acid is broken down by intestinal bacteria into CO2 and ammonia.

Question 4

Outline causes of hyperuricaemia resulting from increased urate formation.

Answer 4

◾ Idiopathic increased purine synthesis.
◾ Enzyme deficiency e.g. HGPRT (Hypoxanthine-Guanine Phosphoribosyltransferase) can lead to increased purine synthesis and subsequently higher urate levels.
◾ Alcohol consumption can disrupt ATP metabolism, leading to increased urate formation.
◾ Hypoxia: low oxygen levels can also disrupt ATP metabolism, contributing to higher levels of urate.
◾ Hematological malignancies: conditions like leukemia and other blood cancers increase cell turnover, leading to higher urate levels.
◾ Psoriasis: This condition causes rapid skin cell turnover, which can increase urate levels.
◾ Cytotoxic drugs: chemotherapy and other cytotoxic drugs can cause rapid cell turnover, leading to increased urate formation.

Further notes:
Psoriasis is a chronic autoimmune skin condition that causes rapid skin cell proliferation, leading to thick, scaly patches on the skin. These patches can be itchy, painful, and sometimes even crack and bleed. Psoriasis can affect various parts of the body, including the elbows, knees, scalp, and lower back.

Question 5

Outline causes of hyperuricaemia resulting from decreased renal urate excretion.

Answer 5

◾ Idiopathic
◾ Renal failure: both acute and chronic renal failure can impair the kidneys’ ability to excrete uric acid, leading to its accumulation in the blood.
◾ Increased renal absorption
◾ Decreased renal secretion: this may be an effect of thiazide diuretics, salicylates, organic acids and poisons, drugs [medications such as ethambutol and pyrazinamide, used to treat tuberculosis, can reduce uric acid excretion]

Question 6

Conditions associated with increased production of uric acid include the following except ________.
(a) malignant disease
(b) cytotoxic therapy
(c) corticosteroid use
(d) psoriasis
(e) increased purine intake

Answer 6

(c) corticosteroid use

Question 7

Conditions associated with hyperuricaemia include the following except ________.
(a) Psoriasis
(b) Cytotoxics
(c) Alcoholism
(d) Renal failure
(e) Hyperthyroidism

Answer 7

(e) Hyperthyroidism

Question 8

Which of the following is not a predisposing factor for hyperuricaemia?
(a) Increased cell multiplication
(b) Increase intake of purines
(c) Increased synthesis of purines
(d) Increased rate of urate formation
(e) Increase turnover of Nucleic Acids

Answer 8

(a) Increased cell multiplication