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Saudi Journal of Kidney Diseases and Transplantation
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Year : 2009  |  Volume : 20  |  Issue : 6  |  Page : 1096-1100
Urolithiasis in Tunisian children: A study of 100 cases

1 Department of Biochemistry and Toxicology, University Hospital, Monastir, Tunisia
2 Department of Pediatric Surgery, University Hospital, Monastir, Tunisia

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Date of Web Publication27-Oct-2009


The aim of this study is to assess the clinical and biological characteristics of renal stone disease among children living in the coastal region of Tunisia. This retrospective multi-center study included 100 children under the age of 16 years, who presented with urinary stones. The patients' charts were reviewed with regard to age at diagnosis, sex, history and physical exami­nation as well as laboratory and radiologic findings. Stone analysis was performed by infrared spec­trophotometry. The male/female sex ratio was 1.5 to 1. The clinical presentation of this pathology was dominated by dysuria. Stones were located in the upper urinary tract in 76 cases (76%). A total of 13% of the study subjects had positive urine cultures. Metabolic investigations were performed in all patients and were normal in 80 cases. Whewellite (calcium oxalate) was found in 77 stones (77.0%). Stone section was made of whewellite in 69.0% of cases and ammonium urate in 47.0%. Struvite stones were more frequently seen in the lower urinary tract. Our study suggests that the epidemiological profile of renal stones in Tunisia has changed towards a predominance of calcium oxalate stones and upper tract location. Also, the male predominance of pediatric urolithiasis is becoming less obvious in Tunisia

How to cite this article:
Alaya A, Nouri A, Najjar MF. Urolithiasis in Tunisian children: A study of 100 cases. Saudi J Kidney Dis Transpl 2009;20:1096-100

How to cite this URL:
Alaya A, Nouri A, Najjar MF. Urolithiasis in Tunisian children: A study of 100 cases. Saudi J Kidney Dis Transpl [serial online] 2009 [cited 2022 Aug 13];20:1096-100. Available from: https://www.sjkdt.org/text.asp?2009/20/6/1096/57276

   Introduction Top

Urolithiasis in children is a frequent disease, characterized by its varied pathophysiological background. [1] Evaluation of a patient with uro­lithiasis include a careful history and a detailed radiological and biochemical evaluation. It is always important to identify the cause of renal stone disease among children to prevent recu­rrence and possible impairment of renal func­tion. [2] A number of publications have previously reported the high prevalence and particular pa­tterns of stone disease among children in deve­loping countries. [3] Our study is aimed at asse­ssing urolithiasis among children in the coastal area of Tunisia.

   Patients and Methods Top

Between 1999 and 2007, 100 children were admitted to the department of pediatric surgery with urolithiasis. In each case, the age and sex of the patient, stone location, and circumstances of discovery were recorded.

The structure of each stone was established using a stereomicroscope to define the morpho­logy of the stones according to the Daudon's classification. [4] The molecular and crystalline composition was determined by infrared spec­troscopy and the various compounds were iden­tified by comparing their spectra with that of the reference ones. [5]

Statistical analysis of these data was carried out using software SPSS 11.0 for Windows.

   Results Top

The study children were aged between eight months and 16 years (mean age, 78 months). About 14% of the cases were infants, aged bet­ween eight months and two years, while the remaining 86% were aged between 26 months and 16 years.

Urolithiasis was more frequent among boys. The sex ratio was 1.5 to 1 (60 boys and 40 girls). This ratio was 7.0 among patients with lower urinary tract stones and 1.05 among those with upper urinary tract stones. Thus, lower urinary tract stones were more frequently seen among boys (n = 23) rather than girls (n = 3) (P < 0.05) and were more frequent among older children rather than infants (P < 0.05). Family history of renal stones was reported in 11 patients (10.6%).

The clinical presentation of this pathology was dominated by dysuria in 29 cases (29.0%) followed by urinary tract infection in 27 cases (27.0%), flank pain in 23 cases (23.0%) and ab­dominal pain in 21 cases. The location of the stone was the kidney or the ureter in 76 cases (76.0%) and the bladder or the urethra in 24 cases (24.0%)

Radio-echographic exploration of the urinary tract allowed the diagnosis of 13 associated uro­logic anomalies: eight cases of ureteropelvic junction obstruction (61.5%), four cases of vesico-uretral reflux (VUR, 30.8%) (unilateral in one case and bilateral in three cases) and one case of posterior urethral valve (7.7%). The older children seem more affected (76.9%) by these malformations than infants (23.1%) (P < 0.05).

Of the patients with urinary infections, Esche­richia coli was the commonest organism iso­lated (53.8%), followed by  Proteus mirabilis Scientific Name Search  (15.3%), Klebsiella pneumoniae Scientific Name Search  (15.3%), Strep­tococcus and Staphylococcus aureus (7.7% each).

Renal failure was noted in one case. Some me­tabolic anomalies were noted in 20.0% of the cases as mentioned under:

  1. Hypercalciuria (infant: > 0.15 mmol/kg/24 hours; child: > 0.1 mmol/kg/24 hours) was seen in nine cases; it was associated with hypercalcemia (infant: > 2.70 mmol/L; child: > 2.60 mmol/L) in one case.
  2. Hyperphosphatemia (infant: > 2.25 mmol/L; child: > 1.85 mmol/L) was seen in nine cases.
  3. Hyperoxaluria (> 0.3 mmol/L) was seen in two cases.
Stone analysis

The composition of stones was homogeneous in 44.0%. Whewellite (calcium oxalate) was found in 77 stones (77.0%), followed by ammonium urate in 49 stones (49.0%) and struvite in nine stones (9.0%) [Table 1]. The composition of the stone section was predominantly whewellite in 69.0% of cases, and predominantly ammonium urate in 47.0% [Table 2]; whewellite was the principal compound in only 19% of the cases [Table 3]. The nucleus of stone was found in six cases (3.6%). The main component of the nuc­leus was ammonium urate in 83.3% of cases. Staghorn stones were noted in 14 cases (14.0%). Their composition was again dominated by whewellite in 53.8%, struvite and carbapatite in 38.5% of cases each.

Stones were treated by surgery (98%), and ureteroscopic extraction (2%). Two patients were treated by nephrectomy.

   Discussion Top

The epidemiologic data relating to the North African pediatric urolithiasis are very heteroge­neous and not easily comparable to those ob­served in industrialized countries. [2],[6] In our study, the male preponderance (sex ratio of 1.5) was more pronounced in patients with lower urinary tract calculi compared with those observed in northern part of Tunisia by Kamoun et al. [3]

In Europe, urinary stones are mainly located in the upper urinary tract, and the proportion of bladder calculi does not exceed 14%. [7],[8] It is ab­sent even in other industrialized countries such as the United States of America. [9] Bladder stones were only observed in the rural areas of the developing countries (51.1% in Morocco, [10] and 71% in Cameroon [1] ). However, they were found in only 18.3% of our study patients. In earlier reports from Tunisia, Najjar et al reported the presence of bladder stones in 36.4% of the pa­tients, [11] while Kamoun et al reported a 24% prevalence. [3]

Urolithiasis mainly affects young children; 20 to 55% of patients are under two years (in­fants). [12],[13] Similarly, in our study, infants ac­counted for 14.0% of the cases; this is com­parable with the latest study by Najjar et al [11] from the same area.

Several studies have noted a strong association between urolithiasis and urinary tract infections. [8],[14] It is not always easy to determine if the infection is the cause or the consequence of lithiasis. The reported frequency of urinary tract infections is about 15 to 57% in patients with urolithiasis. [11],[15] In our series, associated infec­tion was found in 27.0% of the cases, a result that is comparable with that found in North America (28%), [16] Kuwait (29%) [12] and in the Northern region of Tunisia (30%). [14] Also, the prevalence of infection found in the present study is lower than our earlier study in 1986, where we found a prevalence of 57%. [11] Escheri­chia coli was the most frequent bacteria (53.8%), whereas Proteus mirabilis was present only in 15.3% of the cases; these results were in con­formity with Kamoun et al. [3] However, Jungers et al, [15] showed that Proteus remains the most frequent organism associated with renal stone disease.

The metabolic abnormalities seen in our series were lower (20.0%) than those detected in Kuwait, [12] where 83% of the cases had such abnormalities. This can be explained by the low percent of biological investigations performed in our study as well as high degree of con­sanguinity in Kuwait.

Calcium oxalate is the most frequent chemical compound in the urolithiasis; reports suggest that it is present in approximately 80% of stones. [17] Our results agree with these data, which show that whewellite represents the most frequent form (77.0% of stones). Similar results have been observed in Morocco, [18] and Cameroon, [1] as well. An interesting observation in our study is the relatively low prevalence of uric acid stones when compared with data among Tunisian chil­dren in the seventies, when uric stones were the most frequent, seen in 83% of the affected pa­tients. [19] These results confirm the observation of Daudon et al, [20] which places the current pro­file of pediatric urolithiasis in Tunisia between the developing countries and the industrialized ones.

The presence of ammonium urate is especially considered as a marker of endemic urolithiasis, when it is pure or associated with calcium oxa­late. [10] It is particularly rare in the industrialized countries such as France, where the reported prevalence is 4.7%, [4] while it is very commonly seen in childhood stones in developing countries of Africa such as Cameroon, where it reaches 57.1%. [1] In our series, ammonium urate was de­tected only in 47.0% of the cases with a male predominance; the prevalence was 20.56% in 1988. [21]

Struvite remains the best marker of urinary tract infections by urease producing bacteria; [8],[15] with 54% of struvite-containing stones are asso­ciated with clinical infection. [4] These stones can, in some cases, reach a considerable size in the excretory cavities of the kidney, from where the name coralliform stones has come. The frequency of straghorn calculi varies from 19 to 54% in childhood urolithiasis; [22] in our series, the preva­lence was 14.0% and they were associated with urinary tract infections in 38.5% of the cases. The presence of whewellite in 53.8% of the coralliform stones, agrees with the results des­cribed by several authors who found a primary metabolic cause associated with it, mainly in the form of hypercalciuria, [23]

In children with renal calculi, the aims of management should be complete clearance of stones, preservation of renal function and pre­vention of recurrence. In 98 cases, stone remo­val was achieved by open surgery. Our opinion is that open surgical procedures still provide an opportunity to clear stones in complex situa­tions. In our country, open surgery may remain important due to the prevalence of large stones, compounded by the relative lack of availability of facilities for lithotripsy and endourology in most pediatric surgical units. [24]

   Conclusion Top

Our study suggests that the epidemiological profile of renal stones in our country has cha­nged towards a predominance of calcium oxa­late stone and upper tract location due to the high frequency of urate, which might reflect specific eating habits and risk of infections particularly in the rural population. Also, the male predominance of pediatric urolithiasis has become less obvious in recent years.

   References Top

1.Angwafo FF, Daudon M, Wonkam A, et al. Pediatric urolithiasis in sub-saharian Africa: a comparative study in two regions of Cameroon. Eur Urol 2000;37(1):106-11.  Back to cited text no. 1      
2.Kamoun A, Zghal A, Daudon M, et al. Urinary calculi in children: epidemiological, biological and mineralogical aid to diagnosis. Arch Pediatr 1997;4(7):629-945.  Back to cited text no. 2      
3.Kamoun A, Daudon M, Abdelmoula J, et al. Urolithiasis in Tunisian children: a study of 120 cases based on stone composition. Pediatr Nephrol 1999;13(9):920-5.  Back to cited text no. 3      
4.Daudon M. Component analysis of urinary calculi in the etiological diagnosis of urolithiasis in the child. Arch Pediatr 2000;7(8):855-65.  Back to cited text no. 4      
5.Daudon M, Reveillaud RJ. Series of infrared of the urinary tract stones spectra and crystalluria. Laboratoire CRISTAL 1988.  Back to cited text no. 5      
6.Pietrow PK, Pope JC, Adams MC, Shyr YU, Brock JW. Clinical outcome of pediatric stone disease. J Urol 2002;167(2 Pt 1):670-3.  Back to cited text no. 6      
7.Daudon M, Jungers P. Epidemiology of urolithiasis. L'Eurobiologiste 2001;253:5-15.  Back to cited text no. 7      
8.Jungers P, Daudon M, Conort P. Nephroli­thiasis, Diagnostic and treatment. Paris. Flammarion Medecine-Sciences, 1999; 173­-192.  Back to cited text no. 8      
9.Stapleton FB. Childhood stones. Endocrinol Metab Clin North Am 2002;31(4):1001-15.  Back to cited text no. 9      
10.Oussama A, Kzaiber F, Mernari B, et al. Analysis ofcalculi by infrared spectrometry in children from the Moroccan mid-Atlas region. Ann Urol 2000;34(6):384-90.  Back to cited text no. 10      
11.Najjar MF, Najjar F, Boukef K, et al Pediatric lithiasis in the region of Monastir clinical and biological study. Le Biologiste 1986;165:31-9.  Back to cited text no. 11      
12.Al-Eisa AA, Al-Hunayyan A, Gupta R. Pediatric urolithisis in Kuwait. Int Urol Nephrol 2002;33(1):3-6.  Back to cited text no. 12      
13.Basaklar AC, Kale N. Experience with childhood urolithiasis, report of 196 cases. Br J Urol 1991;67(2):203-5.  Back to cited text no. 13      
14.Kamoun A, Daudon M, Kabaar N, et al. Aetiological factors of urinay stones in Tunisian children. Prog Urol 1995;5(6):942-5.  Back to cited text no. 14      
15.Jungers P, Rieu P, Meria P, Knebelmann B, Daudon M. Infection stones. L'Eurobiologiste 2001;254:23-8.  Back to cited text no. 15      
16.Jellouli M, Jouini R, Mekki M, et al. Urinary stones in Tunisian infants, based on a series of 64 cases. Prog Urol 2004;14(3):376-9.  Back to cited text no. 16      
17.Daudon M. Stone analysis and clinical interpretation of the results. L'Eurobiologiste 1993;203:35-46.  Back to cited text no. 17      
18.Bennani S, Debbagh A, Oussama A, El Mrini M, Ben Jalloun S. Infrared spectoscopy and urolithiasis. Ann Urol (Paris) 2000;34(6):376­-83.  Back to cited text no. 18      
19.Nahlovsky J, Farhat M, Gharbi S. extraordinary stones Frequency in Tunisian children and their probable causes.J Urol Nephrol 1969;75:539­-41.  Back to cited text no. 19      
20.Daudon M, Bounxouei B, Santa Cruz F, et al. Composition of renal stones currently observed in non-industrialized countries. Prog Urol 2004; 14(6):1151-61.  Back to cited text no. 20      
21.Najjar MF, Rammah M, Oueslati A, M'henni F, Ben Amor MA, Zouaghi H. Interest of infra red spectrophotometry for urinary calculi analysis. Le Biologiste 1988;176:215-35.  Back to cited text no. 21      
22.Benchekroun A, Lachkar A, Iken A, et al. Staghorn lithiasis: a study of 98 cases. Ann Urol 2000;34(6):370-5.  Back to cited text no. 22      
23.Faure G, Sarramon JP. Staghorn coral-type calculi. J Urol (Paris) 1982;88(7):409-501.  Back to cited text no. 23      
24.Jallouli M, Jouini R, Sayed S, et al. Pediatric urolithiasis in Tunisia: A multi-centric study of 525 patients. J Pediatr Urol 2006;2:551-4.  Back to cited text no. 24      

Correspondence Address:
Akram Alaya
Department of Biochemistry and Toxicology, University Hospital, 5000 Monastir
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Source of Support: None, Conflict of Interest: None

PMID: 19861883

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  [Table 1], [Table 2], [Table 3]

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