title: Stability of the infection marker struvite in urinary stone samples.
abstract: OBJECTIVE
  Struvite in kidney stones is an important marker for infection. In kidney stone samples, struvite is known to be prone to chemical breakdown, but no data exist on the stability of samples stored in dry form. The objective of this study was to examine stability of struvite under increasingly poor conditions of storage.
  
  
  METHODS
  Samples of struvite kidney stones were broken to obtain 38 pieces averaging 67 mg in weight, and these were randomized into four storage conditions: Airtight containers stored in the dark, open containers in the dark, open containers in ambient light, and open containers at elevated temperature (40°C). Pieces were left for 6 months, and then analyzed for changes using micro CT and Fourier transform infrared spectroscopy (FT-IR).
  
  
  RESULTS
  Initial samples proved to be struvite, indicating no transformation in the large specimens that had been stored in airtight containers in the dark for more than 6 years before this study. Pieces of struvite taken from these large specimens appeared unchanged by micro CT and FT-IR after being stored in closed containers for 6 months, but 8 of 9 pieces in open containers showed the presence of newberyite in surface layers, as did 10 of 10 pieces in open containers out in ambient light. All pieces stored at 40°C showed transformation of struvite, with 60% of the pieces showing the presence of amorphous phosphates, indicating complete breakdown of struvite in the surface layers of the pieces.
  
  
  CONCLUSIONS
  We conclude that struvite in dry kidney stone samples is stable when the specimens are stored in airtight containers at room temperature, even after several years.
authors: Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5120, USA. jwillia3@anatomy.iupui.edu
authors: James C
authors: JC
authors: Williams
authors: Andrew J
authors: AJ
authors: Sacks
authors: Kate
authors: K
authors: Englert
authors: Rachel
authors: R
authors: Deal
authors: Takeisha L
authors: TL
authors: Farmer
authors: Molly E
authors: ME
authors: Jackson
authors: James E
authors: JE
authors: Lingeman
authors: James A
authors: JA
authors: McAteer
mesh_terms: D006801:Humans; D007239:Infections / Q000175:diagnosis*; D017616:Magnesium Compounds; D010710:Phosphates; D017550:Spectroscopy, Fourier Transform Infrared; D000069877:Struvite; D014057:Tomography, X-Ray Computed; D014545:Urinary Calculi / Q000000981:diagnostic imaging / Q000382:microbiology*
chemical_list: D017616:Magnesium Compounds; D010710:Phosphates; D000069877:Struvite