Causes Of Hyperuricaemia: High levels of urate in blood is known as hyperuricaemia. It may result from increased turnover (15%) or reduced excretion of urate (85%)
The causes are given below:
- Drugs: cytotoxics, thiazides, loop diuretics,pyrazinamide
- Increased cell turn over: Lymphoma, leukemia, psoariasisf, hemolysis, muscle death-rhabdomyolysis.
- Reduced excretion: Promary gout, chronic kidney disease, lead nephropathy, hyper parathyroidism, pre eclampsia
- Others; Hypertension, Hyperlipedaemia
- Lesch-Nyhan syndrome - a disorder of purine synthesis
How Urate Causes Renal Failure?
Urate is poorly soluble in water so over excretion can lead to crystal precipitation. Renal failure occurs most commonly becauseurate precipitates in the renal tubules. This may occur at a plasma level > 1.19mmol/L. In some instances uretric obstruction from urate crystals may occur. This responds to retrograde uretric catheterization and lavage.
Prevention Of Renal Failure: Before starting chemotherapy , ensure good hydration and initiate allopurinol (xanthine oxidase inhibitor) which prevents sharp rise in urate following chemotherapy.
Treatment Of Hyperuriceamic Acute Renal Failure:
- Exclude bilateral uretric obstruction.
- Then give prompt hydration +/- loop diuretic to wash uric acid crystals out of renal tubules.
- Correct electrolyte abnormalities.
- Once oliguria is established hemodialysis is required
Urate Renal Stones: Urate stones comprise 5-10% of all renal stones and are translucent.
Risk factors for Urate renal stones: includes:
- Acidic urine
- Highly concentrated urine
- Increased urinary excretion of urate
- Chronic diarrhea
- Distal small bowel disease or resection.
- Diabetes mellitus
- Chemotherapy for myeloproliferative disorders
- Inadequate fluid intake
- Hydration to increase urine volume (aim > 2 L/Day)
- Unlike most other renal calculi uric acid stones , can often be dissolved with either systemic or topical alkalinizing agents: Potassium citrate or Potassium bicarbonate at a dose titrated to alkalinize the urine to a pH of 6-7 dissolves some urate stones.
- If hyperuricosuria consider dietary management along with allopurinol/.