Editor,—Akcay et al observed a significantly lower urinary citrate excretion in children with a previous history of urolithiasis.1 Their findings are comparable with data presented in adult stone forming patients, showing a high incidence of hypocitraturia.2 As citrate is a potent inhibitor of calcium-oxalate or calcium-phosphate crystal aggregation,3 hypocitraturia is one important factor influencing recurrent urolithiasis. Urinary citrate excretion, expressed as a citrate/creatinine ratio, in idiopathic stone forming children (n = 25) …