[Factitious lithiasis: Case report from Western Algeria].

A 19-year-old woman with recurrent lithiasis was admitted to the urology department for renal colic. Although radiologic examinations and laboratory tests were negative, the patient regularly brought into consultations small "stones", resembling gravel, that she said had been spontaneously expelled. These 42 samples were the object of a preliminary morphological analysis under a binocular magnifier to detect their particulate components. A non-metabolic origin was suspected from the organoleptic characteristics of their surfaces and sections. In view of the diversity of the materials of these apparently false calculi, methods of precise physical analysis were necessary to ascertain their exact origin and thereby confirm the diagnosis of factitious lithiasis. The use of two methods of physical analysis, infrared spectrophotometry and x-ray diffraction, enabled us to determine their exact chemical and mineralogical composition. The samples claimed to be of urinary origin actually consisted of exogenous products of various compositions. Some samples were made of pure calcite, others of mixed calcite and silicates. Moreover several samples of the patient's first morning urine showed no correlation between the nature of the crystalluria and the composition of these stones. These tests made it possible to direct the clinician towards useful complementary investigations. This strange case represents 0.1% of the urinary calculi analysed in Western Algeria.