struvite and Infections

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.. 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).. 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.. 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.

Topics: Humans; Infections; Magnesium Compounds; Phosphates; Spectroscopy, Fourier Transform Infrared; Struvite; Tomography, X-Ray Computed; Urinary Calculi

Complete metabolic evaluation was performed in 21 patients with infected renal lithiasis. Patients with pure struvite stones (struvite +/- carbonate apatite) were significantly less likely to have metabolic abnormalities than patients who had struvite +/- carbonate apatite+calcium oxalate (2 of 14 v 7 of 7, P = 0.0003). Urine calcium excretion was markedly higher in the mixed stone group than the pure struvite group (342 +/- 98 mg/24 h v 136 +/- 82 mg/24 h; P < 0.0001). The differing opinions among researchers regarding the likelihood of finding metabolic abnormalities in patients with urolithiasis and infection probably reflect differences in the definitions of the populations studied. If patients with calculi containing only struvite +/- carbonate apatite are evaluated, we believe that few significant metabolic abnormalities will be identified.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Apatites; Calcium; Calcium Oxalate; Female; Humans; Infections; Magnesium Compounds; Male; Middle Aged; Phosphates; Sex Characteristics; Struvite; Urinary Calculi; Urine