|Year : 2015 | Volume
| Issue : 2 | Page : 117-119
Renal silica calculi in children: Report of two cases and review of literature
VBR Gouru, SP Vaddi, SR Dadireddy, S Gnanaguruswamy
Department of Urology and Renal Transplantation, Narayana Medical College, Chintareddypalem, Nellore, Andhra Pradesh, India
|Date of Web Publication||16-Jun-2015|
Dr. VBR Gouru
Department of Urology and Renal Transplantation, Narayana Medical College, Chintareddypalem, Nellore - 524 003, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Renal silicate calculi are rare, with an incidence of 0.2% of all urinary calculi in humans. Several case reports showing that the long-term administration of magnesium trisilicate induced silica renal calculi. We report two cases of silicate renal calculi in children and the composition is purely silicon dioxide (100%) in both cases. The first child was a 7-year-old boy who presented with fever, vomiting, and loin pain for 2 months. His father and younger sister had undergone interventions for renal calculi. Intravenous urogram (IVU) revealed a left renal calculus of 2.2 × 1.8 cm which was treated by percutaneous nephrolithotomy (PCNL). The second case was an 8-year-old girl who's clinical and radiological evaluation lead to a diagnosis of left renal calculi which was treated by PCNL. In both cases the composition of the stone was 100% silicon dioxide.
Keywords: Renal silica in humans, silica calculi, silica renal calculi in children
|How to cite this article:|
Gouru V, Vaddi S P, Dadireddy S R, Gnanaguruswamy S. Renal silica calculi in children: Report of two cases and review of literature. Arch Int Surg 2015;5:117-9
|How to cite this URL:|
Gouru V, Vaddi S P, Dadireddy S R, Gnanaguruswamy S. Renal silica calculi in children: Report of two cases and review of literature. Arch Int Surg [serial online] 2015 [cited 2020 Oct 24];5:117-9. Available from: https://www.archintsurg.org/text.asp?2015/5/2/117/158828
| Introduction|| |
Renal silicate calculi are rare, with an incidence of 0.2% of all urinary calculi in humans.  There are several reports ,, showing that the long-term administration of magnesium trisilicate antacid in patients with gastric and duodenal ulcers induces silica urinary calculi. Urinary silicate calculi without any predisposing causes have also been reported in literature. Silica calculi in children and infants are very rare. We report idiopathic silicate renal calculi in two children who underwent percutaneous nephrolithotomy (PCNL) for stone clearance.
| Case Report|| |
A 7-year-old boy presented with fever, vomiting, and loin pain for 2 months. His father and younger sister had undergone interventions for renal calculi. The urine pH was 6.5 and urinary sediment showed 6-8 WBC (white blood cells)/HPF (High Power Field). Urine culture was positive for Escherichia More Details coli (10 5 CFU (colony forming units)/ml). Serum biochemistry (serum creatinine, serum calcium, phosphorus, and uric acid) were unremarkable. On investigation, he was found to have radiopaque left renal calculus 2.2 × 1.8 cm on intravenous pyelogram. The patient underwent left PCNL. The stone fragments were hard and brown in color [Figure 1]a. Stone analysis of sibling revealed mixed stone with combination of whewhelite, carbonate, and weddelite.
An 8-year-old girl presented with left loin pain and fever for 1 week. The urinalysis revealed a pH of 6.0. Peripheral blood count and his serum chemistry were unremarkable. On radiologic evaluation, a radiopaque left renal calculus [Figure 2] was seen. She underwent left PCNL. The stone had a rough surface and light brown in color on gross examination [Figure 1]b.
|Figure 2: Axial CT section showing left renal calculi. CT = Computerized tomography|
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In both cases calculi composed of column-shaped crystals of alpha-quartz ended with rhombohedron surfaces. No distinct nidus was seen microscopically. On Fourier transform infrared (FTIR) spectroscopy analysis, its wavelength pattern exhibited a peak at 1,100-1,200 cm−1 [Figure 3]. The composition of the stone was 100% silicon dioxide (SiO 2 ). Both children had no history of taking magnesium trisilicate, antiepileptic drugs, or any other medications. The 24-h LithoRisk analysis was unremarkable in both children.
|Figure 3: Fourier transform infrared (FTIR) analysis showing wavelength peak at 1,100-1,200 cm−1|
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| Discussion|| |
Silica is a major component of sand; granite; quartz; and other types of rocks, clays, and gems in the Earth's crust.  Silicon dioxide is poorly soluble in water. Urinary silicate calculi are common in herbivorous animals such as bovine and cattle, but rare in humans. , Most of human reports (50 cases) are from Japan. ,,,, The age of reported cases ranged from 24 to 77 years. Toshiyuki et al., reported mixed silicate (78%) and calcium oxalate (22%) renal calculi in an infant fed with silicate-rich water for diluting milk.  We report two cases in children of 7-8 years, without any predisposing factor.
Silicate urinary calculi are known to occur in patients taking large amount of antacids containing silicate. When a silicate reacts with acid in the stomach, part of the silica is precipitated as a gel and part remains as a solution in the form of a colloid. The silicates in the solution form are readily absorbed across the intestinal wall and excreted rapidly in the urine. Alkalization by the gut fluid changes a silica colloid into a more soluble and absorbable compound. , Urinary excretion of silicates is directly proportional to the dietary silicate intake. King et al.,  in their animal studies showed that, introduction of soluble or of particulate silica into the stomachs of animals lead to marked increase in the output of silicates in the urine without any corresponding increase in the blood. Page  reported that the urinary silica concentration depends on intake of silica-containing foods such as vegetables, grains, or sea food. In volunteers, the urinary silica went up from a pretreatment level of 1.46 to 12.27 mg/dL who received 5 g of magnesium trisilicate per day. This elevation was apparent on the 2 nd day of administration. The urinary silica decreased to 1.8 mg/dL on the 2 nd day after discontinuation of the magnesium trisilicate. 
Along with increased dietary intake, alkaline urine predisposes to silicate stone formation. The urinary pH of patients with silica stones is found to be alkaline in various case reports. , According to Takemoto et al., the trigger of silicate stone formation is urine alkalinization.  He proposed that high concentration of the silicate in the urine induces aggregation of the silicate and later the deposition of the calcium salt around silicate aggregates is driven by urine alkalinization.  Urine pH is within normal range in our patients. The alkaline urine and concentration of silica are important determinants for silica calculi. The random sample of human urine contains an average of 1.31  to 1.46 mg/dL.  Haddad and Kouyoumdjian reported that his patient with silicate urolithiasis had 6 mg/dL.  The sibling of the above mentioned first case had calcium oxalate and carbonate mixed stone composition though they share same dietary and environmental factors. The cause for silica calculi could not be found in our cases.
| Conclusion|| |
Silicate renal calculi in humans are rare entity. Increased dietary intake in the form of silicate containing antacids and alkaline urine predispose to silicate calculi. Still various idiopathic cases have been reported. Stone analysis and characteristic wave pattern on FTIR can establish the diagnosis. Silicate renal calculi in children without any predisposing causes are extremely rare.
| References|| |
Haddad FS, Kouyoumdjian A. Silica stones in humans. Urol Int 1986;41:70-6.
Lee MH, Lee YH, Hsu TH, Chen MT, Chang LS. Silica stone - Development due to long time oral trisilicate intake. Scand J Urol Nephrol 1993;27:267-9.
Page RC, Heffner RR, Frey A. Urinary excretion of silica in humans following oral administration of magnesium trisilicate. Am J Dig Dis 1941;8:13-5.
Martin KR. The chemistry of silica and its potential health benefits. J Nutr Health Aging 2007;11:94-7.
Takemoto M, Itatani H, Kinoshita K, Yachiku S. Silica calculi (author′s transl). Nihon Hinyokika Gakkai Zasshi 1978;69:664-8. Japanese.
Nishizono T, Eta SI, Enokida H, Nishiyama K, Kawahara M, Nakagawa M. Renal silica calculi in an infant. Int J Urol 2004;11:119-21.
Toba T, Koike H, Nobushita T. Staghorn silicate calculi: A case report. Hinyokika Kiyo 2012;58:325-8. Japanese.
Kobayashi K, Ohara S, Yano A, Tacho T, Fujii M, Mutaguchi K. Silicate calculi: A case report. Nishinihon J Urol 2004;66:507-10.
King EJ, Stantial H, Dolan M. The biochemistry of silicic acid: The excretion of administered silica. Biochem J 1933;27:1007-14.
King EJ, Stantial H. The biochemistry of silica acid. I: Micro-determination of silica. Biochem J 1933;27:990-1001.
[Figure 1], [Figure 2], [Figure 3]