Medical Management of Hypocitraturia

Abstract

Nephrolithiasis is a common disorder which left untreated has a high rate of recurrence. Hypocitraturia is a significant risk factor for the development of calcium kidney stones, and is present in up to 60 % of stone formers. Urinary citrate is an endogenous inhibitor of stone formation. Citrate forms soluble complexes with calcium, thereby reducing urinary free calcium. Furthermore, calcium-citrate complexes inhibit crystal nucleation, growth, and aggregation. Most often hypocitraturia is idiopathic, but may be associated with medical conditions such as renal tubular acidosis, gastrointestinal malabsorption, and hypokalemia. Diets high in animal protein and certain medications such as carbonic anhydrase inhibitors are also associated with hypocitraturia.

Dietary modifications have been shown to increase urinary citrate excretion and should be considered for stone formers with hypocitraturia. Potassium citrate has been demonstrated in prospective, randomized controlled trials to decrease the risk of recurrent calcium stones and decrease growth of residual stones after shock wave lithotripsy and percutaneous nephrolithotomy. There are no randomized controlled trials comparing dietary therapy to medical prophylaxis to reduce recurrent stone disease. Potassium citrate therapy should be utilized concurrently with dietary modifications in recurrent calcium stone formers with hypocitraturia. Sodium citrate therapy may be considered in stone formers intolerant to potassium citrate.