title: The systematic classification of gallbladder stones.
abstract: BACKGROUND
  To develop a method for systematic classification of gallbladder stones, analyze the clinical characteristics of each type of stone and provide a theoretical basis for the study of the formation mechanism of different types of gallbladder stones.
  
  
  METHODS
  A total of 807 consecutive patients with gallbladder stones were enrolled and their gallstones were studied. The material composition of gallbladder stones was analyzed using Fourier Transform Infrared spectroscopy and the distribution and microstructure of material components was observed with Scanning Electron Microscopy. The composition and distribution of elements were analyzed by an X-ray energy spectrometer. Gallbladder stones were classified accordingly, and then, gender, age, medical history and BMI of patients with each type of stone were analyzed.
  
  
  RESULTS
  Gallbladder stones were classified into 8 types and more than ten subtypes, including cholesterol stones (297), pigment stones (217), calcium carbonate stones (139), phosphate stones (12), calcium stearate stones (9), protein stones (3), cystine stones (1) and mixed stones (129). Mixed stones were those stones with two or more than two kinds of material components and the content of each component was similar. A total of 11 subtypes of mixed stones were found in this study. Patients with cholesterol stones were mainly female between the ages of 30 and 50, with higher BMI and shorter medical history than patients with pigment stones (P<0.05), however, patients with pigment, calcium carbonate, phosphate stones were mainly male between the ages of 40 and 60.
  
  
  CONCLUSIONS
  The systematic classification of gallbladder stones indicates that different types of stones have different characteristics in terms of the microstructure, elemental composition and distribution, providing an important basis for the mechanistic study of gallbladder stones.
authors.affiliation: Laboratory of Gallbladder Diseases, Institute of Gallbladder Disease of Panyu, Panyu, Guangzhou, People's Republic of China ; Laboratory of Gallbladder Diseases, The Sixth People's Hospital of Nansha, Nansha, Guangzhou, People's Republic of China.
authors.forename: Tie
authors.initials: T
authors.lastname: Qiao
authors.forename: Rui-hong
authors.initials: RH
authors.lastname: Ma
authors.forename: Xiao-bing
authors.initials: XB
authors.lastname: Luo
authors.forename: Liu-qing
authors.initials: LQ
authors.lastname: Yang
authors.forename: Zhen-liang
authors.initials: ZL
authors.lastname: Luo
authors.forename: Pei-ming
authors.initials: PM
authors.lastname: Zheng
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D042882:Gallstones / Q000145:classification* / Q000648:ultrastructure*; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D017550:Spectroscopy, Fourier Transform Infrared; D055815:Young Adult