Silica in Urinary Calculi

Silica Stones in Humans

“…Silica and silicates are being found with increasing fre quency as laminae or nuclei in urinary calculi made up of other urinary constituents [12].…”

“…Rarely, a large stone may get impacted and retained either in the renal pelvis [6,8], in the ureter [9,12] or in the bladder [11] (table VII). In animals, silica stones have been found all along the uri nary tract (table VIII).…”

“…The form in which silica could be found in stones is either a gel (opaline) form [6,26] or a quartz-like crystal line form [12], Silica stones were pure in 4 patients [this study, 8,11,25]; frequently they contained other ingre dients such as oxalate [25], iron [2,4,5], ammonium [ 12], traces of phosphate [5] or fibrin [6], Silica was found in 4 out of 10 renal apatite, struvite and urate stones and in 17 struvite stones in concentrations of up to 0.46% of silica [12]. A proportion of struvite stones (probably 0.7%) contained a concentration of up to 6% silica [3].…”

“…Ten cases are well documented and genuine, the reports contain sufficient data to permit their review and analysis; 6 cases (5 [25] and 1 [12]) do not have sufficient clinical data to allow analysis; 4 cases are so-called 'fakes' (2 cases [2] and 1 case [4]) or of doubtful authenticity [5].…”

“…Several methods have been used in the analysis of sil ica stones [35,36] including the following: (1) X-ray dif fraction [8,[24][25][26]; the use of the energy dispersive anal ysis of x-ray (EDAX) analyzator gives specific bands for opaline (amorphous) silica at 4.420, 1.625, 1.100, 950, 790 and 470 [10,12]; more frequently than not, x-ray diffraction produces uninterpretable diffraction rings; clear diagnostic diagrams can be obtained after heating the sample [25]; (2) chemical [3,5,26]; (3) infrared spec troscopy [8,9,11]; (4) photometric absorption [6] or atomic absorption spectrometry [ 12]; (5) emission spectrography and neutron activation analysis [3], and (6) XES [11].…”