[Nephrolithiasis: From mechanisms to preventive medical treatment]

Renal lithiasis is a frequent pathology (prevalence ranging from 10 to 12% in France) and a recurrent condition. It is associated with chronic kidney disease and is responsible for 2 to 3% of cases of end-stage renal disease, especially if it is associated with nephrocalcinosis and/or is part of a monogenic disease (1.6% of lithiasis in adults, including 1% of cystinuria). In order to understand the pathophysiology of the nephrolithiasis, the analysis of stones (morphological and by infrared spectrophotometry) as well as a minimal biological evaluation including crystalluria must be carried out. Calcium nephrolithiasis is the most common form (more than 80%). Its preventive medical treatment relies on simple hygienic dietetics: non-alkaline hyperdiuresis greater than 2liters/day, normalization of calcium intakes (1g/day to be distributed over the three meals), restriction of sodium intakes (6g/day) and of protein intakes (0.8-1g/kg of theoretical weight/day), and avoidance of foods rich in oxalate. If there is a hypercalciuria (greater than 0.1mmol/kg of theoretical weight/day with normal calcium intakes), its mechanism should be explored with an oral calcium load test. In the absence of primary hyperparathyroidism, thiazide diuretics can be prescribed, taking care to prevent hypokalemia and iatrogenic hypocitraturia. The treatment of uric acid lithiasis includes alkaline hyperdiuresis (urinary pH 6.2 to 6.8). Allopurinol is only justified if the urinary excretion of uric acid exceeds 4mmol/day. With a well-managed medical treatment, more than 80% of recurrent lithiasis can be stopped, making nephrolithiasis one of the kidney diseases the more accessible to the preventive medical treatment.