Cautionary Note Regarding Urinary Calculi Analysis with the Merckognost® Kit

Abstract

Our laboratory has been using the Merckognost® (E. Merck) urinary calculi analysis kit for renal calculi analysis. A review of results from 1994 (performed with lot nos. 03053, 03050, 07092, 16124, 10034, 14085, 16124, and 12036) showed the presence of calcium oxalate in all stones except one that was pure uric acid. Although calcium oxalate because of its high insolubility is the most common component of renal calculi, its presence in 99.8% of the stones analyzed was much higher than reported in literature (Table 1⇓ ). In a large series of 10 438 stones analyzed by infrared spectroscopy with microsampling (1), calcium oxalate was reported present in 86% of stones. In addition, the absence of pure calcium phosphate stones was unusual, because most studies report 5–21% of stones as pure calcium phosphate (2)(3)(4). View this table: Table 1. Distribution of calculi composition (%) in our laboratory …