Hyperuricemia

HyperuricemiaHyperuricaemia is defined as elevated levels of uric acid (≥7 mg/dL) in the blood and may be caused by either urate over production or under excretion.

Clinical presentation

Patients with hyperuricemia may be asymptomatic or have symptoms and signs relating to one of the complications of hyperuricemiahyperuricaemia (eg. gout, nephrolithiasis).

Pathology

Uric acid is produced as the end product of purine nucleotide degradation. Hypoxanthine and xathine are the intermediates which are converted to uric acid via the enzyme xanthine oxidase. Uric acid is mostly excreted via the kidneys with the rest being excreted intestinally, but up to 90% is resorbed via the transporters URAT1 and GLUT9 in the kidneys ^1,2. HyperuricemiaHyperuricaemia may result from urate under excretion, overproduction or a combination of both.

Causes:

• Under excretion³:
  • Idiopathic
  • Renal insufficiency
  • Metabolic syndrome
  • Drugs (eg. diuretics)
  • Preeclampsia and eclampsia
  • Sarcoidosis
• Overproduction:
  • Idiopathic
  • Lesch-Nyhan syndrome
  • High purine diet
  • Tumor lysis syndrome
  • Haematological diseases (eg. hemolytic anaemia, lymphoma, leukemia)
• Combined:
  • Alcohol
  • G6PD

Radiological features

No radiological features are specific for hyperuricemiahyperuricaemia. Signs of complications of hyperuricemiahyperuricaemia may be visible (eg. gout, nephrolithiasis).

Treatment and prognosis 

HyperuricemiaHyperuricaemia is treated by addressing the underlying cause of urate overproduction or under excretion, xanthine oxidase and URAT1 inhibitors are also commonly used ². HyperuricemiaHyperuricaemia is a risk factor for cardiaccardiovascular disease and gout ^2,3.