專技 - 藥物治療學題庫下載題庫

The medical management of uric acid nephrolithiasis includes hydration sufficient to maintain a urine volume of at least 2 to 3 L/day, alkalinization of urine, avoidance of purine-rich foods, moderation of protein intake, and reduction of urinary uric acid excretion.

Maintenance of a 24-hour urine volume of at least 2 L with an adequate intake of fluids is desirable for all patients with gout, but especially for those who form stones. Alkalinizing agents should be used with the objective of making the urine less acidic. Urine pH should be maintained at 6 to 6.5.⁸⁰ In this pH range, up to 85% of uric acid will be in the form of the soluble urate ion.

Reduction of urine acidity is usually accomplished by the administration of potassium bicarbonate or potassium citrate 30 to 80 mEq/day (mmol/day).⁸⁰Administration of alkali via sodium salts is a less desirable option for two reasons. First, the sodium-induced volume expansion will increase sodium excretion and can secondarily cause hypercalcemia because calcium passively follows the reabsorption of sodium in the proximal tubule and loop of Henle. In the presence of uric acid, the resultant hypercalcemia can lead to calcium oxalate stone formation. Second, older patients with uric acid kidney stones may also have hypertension, heart failure, or impaired kidney function. Because of these conditions, they should not be overloaded with alkalinizing sodium salts or unlimited fluid intake, as these can worsen these conditions.⁸⁰

Carbonic anhydrase inhibitors (eg, acetazolamide and topiramate) produce rapid and effective urinary alkalinization; however, they are not recommended because they cause metabolic acidosis and hypocitraturia which may result in increased urinary saturation of calcium salts and calcium stone formation.