Silica stones in humans.

Twenty cases of silica stones (including a personal one, the first case ever observed--April 1952) are reviewed. Almost all of the patients had been taking magnesium trisilicate for several years, one up to 40 years. The average age of the patients was 54 years. There were 9 males and 1 female. The patients came from the following locations, given in chronological order: Beirut, Lebanon (1952); Stockholm, Sweden (1953, 1962); Houston, Tex., USA (1958, 1961); New York, N.Y., USA (1960); Johannesburg, South Africa (1964); London, UK (1973, 1982); Osaka, Japan (1978); Madrid, Spain (1978, 1981); and Torrance, Calif., USA (1984). 14 patients passed out the stones spontaneously. In 3 patients, the stone was formed in the left kidney. Bilateral renal stones were found in 2 patients. In 2 patients, they were removed from the left ureter and in 2 patients they were found in the bladder. The size of the stones varied between 2 mm and 3 cm, the weight from 8 mg to 3.6 g. The silica stone is of a relatively low radio density. Our case is the only one in whom the level of urinary silica was determined; it was of the order of 0.006% i.e. 1 mmol/l.