title: High Prevalence of Opaline Silica in Urinary Stones From Burkina Faso.
abstract: OBJECTIVE
  To underline peculiar composition of kidney stones and to propose an epidemiologic study of urinary stones in West African countries, where epidemiologic studies are scarce. Only few data are available regarding stone composition in sub-Saharan countries. Recently, a set of 100 stones consecutively removed by surgery in the Department of Urology of the University Hospital of Ouagadougou in Burkina Faso were collected for physical analysis, which provided the opportunity to obtain an epidemiologic profile of stone composition in this country.
  
  
  METHODS
  A total of 100 stones from 64 men, 22 women, 10 boys, and four girls were analyzed by morphologic examination, infrared spectroscopy, and electron microscopy in our laboratory. The results were considered by sex and separately for adults and children.
  
  
  RESULTS
  Sixty-five percent of the 100 stones contained calcium oxalate as the main component. Interestingly, the second main component was opaline silica (18%). Furthermore, opaline silica was identified in any proportion in 48% of the stones. The prevalence was sex and age dependent. Opaline silica was detected as the main component in 42% of the nuclei, which underlines its role as one of the main components involved in the initiation of calculi in this country.
  
  
  CONCLUSIONS
  For the first time, a dramatically high occurrence of a "scarce" urinary stone component, namely opaline silica, was reported in a series of consecutive calculi from a single country. We propose that a regular consumption of clay could be the origin of this phenomenon in these populations.
authors.affiliation: CNRS, Laboratoire de Physique des Solides, Université Paris XI, Orsay, France; INSERM, UMR 1138, Centre de Recherche des Cordeliers, Laboratoire de Physiopathologie Orale Moléculaire, Equipe Berdal, Université Paris-5, Université Paris-6, Université Paris-7, Paris, France. Electronic address: arnaud.dessombz@crc.jussieu.fr.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Dessombz
authors.affiliation: Service Urologie, CHU Yalgado Ouédraogo, Ouagadougou, Burkina Faso.
authors.forename: Brahima
authors.initials: B
authors.lastname: Kirakoya
authors.affiliation: Service de Néphrologie et Hémodialyse, CHU Yalgado Ouédraogo, Ouagadougou, Burkina Faso.
authors.forename: Gérard
authors.initials: G
authors.lastname: Coulibaly
authors.affiliation: Service Urologie, CHU Yalgado Ouédraogo, Ouagadougou, Burkina Faso.
authors.forename: Richard W
authors.initials: RW
authors.lastname: Ouedraogo
authors.affiliation: CNRS, Laboratoire de Physique des Solides, Université Paris XI, Orsay, France; CNRS, Institut des Nanosciences, Université Paris VI, Paris, France.
authors.forename: Lise
authors.initials: L
authors.lastname: Picaut
authors.affiliation: CNRS, Laboratoire de Physique des Solides, Université Paris XI, Orsay, France.
authors.forename: Raphael
authors.initials: R
authors.lastname: Weil
authors.affiliation: CNRS, Laboratoire de Chimie de la Matière Condensée de Paris, UPMC Paris-6, Collège de France, Paris, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Bazin
authors.affiliation: APHP, Service des Explorations Fonctionnelles, Hôpital Tenon, Paris, France; INSERM, UMR S 1155, Hôpital Tenon, Paris, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Daudon
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002050:Burkina Faso / Q000453:epidemiology; D002129:Calcium Oxalate / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000737:chemistry* / Q000453:epidemiology*; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D015995:Prevalence; D012737:Sex Factors; D012822:Silicon Dioxide / Q000032:analysis*; D017550:Spectroscopy, Fourier Transform Infrared; D055815:Young Adult
chemical_list: C029019:opoka; D002129:Calcium Oxalate; D012822:Silicon Dioxide