|Year : 2009 | Volume
| Issue : 2 | Page : 39-43
Pediatric urololithiasis in coastal Tunisia
Akram Alaya1, Nouri Abdellatif2, Mohammed Fadhel Najjar1
1 Department of Biochemistry and Toxicology, Fattouma Bourguiba Hospital, Monastir, Tunisia
2 Department of Pediatric Surgery, Fattouma Bourguiba Hospital, Monastir, Tunisia
|Date of Submission||17-Oct-2008|
|Date of Acceptance||05-Aug-2009|
|Date of Web Publication||26-Sep-2009|
Department of Biochemistry and Toxicology, Fattouma Bourguiba Hospital, 5000 Monastir
| Abstract|| |
Context: We will try to show an outline of the clinical and biological characteristics of pediatric urolithiasis among Tunisian children in the coastal region.
Materials and Methods: This retrospective study included 168 children below 16 years (100 boys and 68 girls) presented with urinary stones. Patients were reviewed in a multi-centric study with regard to age at diagnosis, sexual, historical, physical, laboratory, and radiologic findings. The physical and chemical analysis of stones was carried out by a stereomicroscope and infra-red spectroscopy respectively.
Statistical Analysis: Statistical analysis of data was carried out using software SPSS 11.0 for Windows. Statistical significance was determined using chi-square test.
Results: The sex ratio was 1.47. Clinical presentation of this pathology was dominated by abdominal pain (28%), hematuria (25.6%), dysuria (16.7%) and urinary tract infection (14.3%). Stones were located in the upper urinary tract in 75.6% of cases. Of the urine cultures, 14.3% were positive. Whewellite is found more frequently in children stones than infants (P < 0.05) and was the main component in 46.4% of stone section and 55.4 % of stone surface. Stuvite stones were more frequent among boys stones than girls' (11 Vs 2.9%) (P < 0.05).
Conclusions: The male prevalence of pediatric urolithiasis is less obvious in Tunisia. Calcium oxalate is the most frequent chemical compound in Tunisian pediatric urolithiasis.
Keywords: Children, infrared spectroscopy, stone, Tunisia
|How to cite this article:|
Alaya A, Abdellatif N, Najjar MF. Pediatric urololithiasis in coastal Tunisia. Urol Ann 2009;1:39-43
| Introduction|| |
Urolithiasis in children is a frequent disease characterized by its varied patho physiological background.  Clinical investigations of a patient with urolithiasis include a careful history, radiological and biochemical evaluation. It is always important to define the cause of urinary calculi disease among children to prevent recurrence and possible impairing of renal function.  A number of publications have previously reported the high prevalence and particular patterns of stone disease among children in developing countries.  Our study is interested in the urolithiasis of the child in the area of the Tunisian coast. By confronting the clinical data and the results from stone analysis, we will try to show an outline of the clinical and biological characteristics of pediatric urolithiasis among Tunisian children.
| Materials and Methods|| |
Between June 1996 and February 2008, 168 children (68 females, 100 males; mean age 7.3 years; age range 0.25- 16 years) suffering from urinary calculi and evaluated in our department were enrolled in the study. In each case age and sex of the patient, stone location, and circumstances of discovery were recorded. Various biochemical parameters indicative of renal functional status (serum calcium, phosphorus, alkaline phosphatase, creatinine, uric acid and electrolyte levels) were evaluated in 126 cases.
The structure of each calculus was established using stereomicroscope to define the morphology of the stone and select its representative parts (nucleus or core, internal section, and external surface), in order to determine its molecular and crystalline composition by infrared spectroscopy. About 0.5 to 2 mg powder of each stone part was pulverized with an inert powdered support (dried potassium bromide) in a proportion of 0.5 to two per cent in an agate mortar. This mixture was transferred into an appropriate die and pressed at 10t/cm 2 to form a transparent pellet 13 mm in diameter. The spectral region investigated was from 4000 to 400 cm -1 . Reference spectra were pure potassium bromide (KBr) pellets. Spectra were recorded by means of a Bruker IFS25 Fourier transform infrared spectrometer. The various compounds were identified by comparison with previously published reference spectra.
Results were expressed according to the main crystalline phase found in the stones and named as follows: whewellite (calcium oxalate monohydrate), weddellite (calcium oxalate dihydrate), carbapatite (carbonated calcium phosphate crystallized in the hexagonal system), struvite (magnesium ammonium phosphate hexahydrate), and calcite (anhydrous calcium carbonate). The stone component was considered the main one if it exceeded 70% of the total composition of calculus. Statistical analysis of these data was carried out using software SPSS 11.0 for Windows.
| Results|| |
Children under study were aged between three months to 16 years (mean age 7.3 years). About 15.47% of the cases were infants aged between three months and two years. Urolithiasis was more frequent among boys. The sex ratio was 1.47 (100 boys and 68 girls); ratio was 2.71 among infant patients. The most frequent initial symptoms were abdominal pain (28.0%) [Table 1], which was prevalent in school going child (30.3% in children vs. 15.4% in infant) (P < 0.05), hematuria in 25.6% of cases and dysuria in 16.7%. Infants seem to be more frequently affected by urinary tract infection than children (26.9 vs 12.0%) (P < 0.05). A family history of urolithiasis was recorded for 19 patients (8.9%).
Thirteen patients (7.7%) had an underlying anatomic abnormality, including vesicoureteral reflux in four cases, uretero-pelvic junction obstruction in eight cases and valves of the posterior urethra in one case. Urinary calculi were more frequently located in the upper urinary tract (75.6%) than either the lower urinary tract [Figure 1]. Bladder stone was more frequent in boys than girls (29.0 vs 7.4%) (P < 0.05). Multiple stones were found in 108 patients (64.2 %).
Evaluation of metabolic risk factors in 24-hour urine samples revealed 22 children (13.1%) with a single risk factor. Among these, hyperoxaluria (three cases), hypercalciuria (11 cases), cystinuria (two cases) and hypocitraturia (six cases) seemed to be the commonest. Among the possible predisposing factors, 24 patients (14, 3%) had urinary tract infection (UTI) at the time of diagnosis and were treated with appropriate medication. The bacteria isolated were Proteus in 12 cases, Escherichia More Details coli in eight, Klebsiella pneumoniae in two, and Streptococcus and Staphylococcus aureus in one case each. About 167 children were treated by open surgery and one by endoscopy.
The stone composition was homogeneous (greater than 90-95% of stone composition) in 37.5% of cases and calcium oxalate stone represent its principal component (60.0%), which was more frequent in children (63.4%) than infants (46.1%) (P < 0.05). Purine stones were pure in 24.6% of cases mostly observed in children (21.1 vs. 38.4% in infants) and boys (30.7 vs. 15.4% in girls) (P < 0.05).
As shown in [Table 2], the main component of the urinary stones - determined by infrared spectroscopy - was whewellite in 89 cases (53.3%). It was present in 54.7% of the stone sections and 70.2% of the surface [Figure 2]. Struvite stones were more frequent in boys than girls (P < 0.05) and were associated with urinary tract infection in 66.6% of cases. Struvite and Uric acid anhydrous were more frequent in infants than in children (P < 0.05) [Table 3].
The nucleus of stone was found in six cases (3.5%). The main component of the nucleus was ammonium urate in 33.3% of cases. Staghorm stones were noted in 14 cases. Their composition was dominated by whewellite in 53.8%, struvite and carbapatite each one in 38.5% of cases.
| Discussion|| |
The epidemiologic data relating to North African pediatric urolithiasis is very heterogeneous and not easily comparable to data from industrialized countries. ,
The well-known male preponderance has been confirmed in our study; however, this predominance is progressively decreasing compared to results previously published since the end of sixties. , According to some publications urolithiasis mainly affects baby (less than two years of age) than children. ,,
In Tunisia, baby urolithiasis was reported for the first time by Nahlovsky in the area of Sousse,  where a frequency of 31.4% was recorded. Ten years later, in the same area, Najjar et al.  reported a frequency of 37.8%. During the past 25 years, this frequency changed in the central coast of Tunisia and currently accounts for 15.47%.
Several studies noted a strong association between urolithiasis and urinary tract infections. , It is not always easy to determine if the infection is the cause or the consequence of lithiasis. The frequency of urinary tract infections was about 15 to 57% of lithiasic patients in the years 1970-1980 , and does not exceed two per cent in Europe at present.  In our series, infection reached 14.3% of cases comparable with that found in North America (eight per cent).  This result was lower than that observed in England (30%),  Kuwait (29%)  and the Northern region of Tunisia (30%) (10) but shows a decrease in infection when compated with our first study in 1986 where we find 57% infection cases.. 
The metabolic abnormalities in our series (13.1%) are lower than those detected in Kuwait  where they reach 83% of cases. This can be explained by the low level of biological investigation in our study and high level of consanguinity in Kuwait.
In Europe, urinary stones are mainly located in the upper urinary tract and the proportion of bladder calculi does not exceed 14%. , It is absent even in other industrialized countries such as the United States of America.  Bladder stones were observed only in rural areas of developing countries (51.1% in Morocco  and 71% in Cameroon).  However, in the case of our patients, they were found in only 20.2% of cases (Najjar et al. (36.4%),  Kamoun et al. (24%). 
Calcium oxalate is the most frequent chemical compound in urolithiasis present in approximately 80% of stones and represents the majority component in 70% of them. 
The data agree with our results which show that calcium oxalate was the main component in 105 cases (62.5%). It was present in 54.7% of the stone sections and 70.2% of the surface. However, these values were lower than those described in Pakistan (surface 85%, section 90%).  This frequency is comparable with that observed in Morocco,  Cameroon,  and in our precedents studies, , but shows a considerable modification of the stone composition of Tunisian children since the seventies, where uric stone represent 83%.  These results confirm those observed by Daudon et al.  which place the current profile of pediatric urolithiasis in Tunisia between developing countries and industrialized ones.
Calcium oxalate monohydrate (whewellite) remains the most frequent component in Tunisian children and infants stones ,, even if its frequency slightly decreased during the last 12 years period.  We found that whewellite was the main component in 53.3% of stones and its frequency was higher on the level of the stone surface.
The presence of ammonium urate is especially considered as a marker of endemic urolithiasis when it is pure or associated calcium oxalate and that constitutes the core of stones.  It is particularly rare in industrialized countries where it reaches 4.7% in France  and abundant for childhood stones of the developing countries of Africa such as Cameroon where it reaches 57.1%.  Ammonium urate was the main component in only 13.8 % of cases, and 19% of the stones section in our series.
According to our results, purine (ammonium urate plus uric acid anhydrous) stones were more frequent in infants than children. Metabolic (genetic or acquired) disorder can be mentioned to explain this change. However, we believe that tubular immaturity in infants associated to a lack of reabsorption of uric acid is the main reason in this case. 
Struvite remains the best marker of urinary tract infections by urease producing bacteria; , 54% of struvite-containing stones are associated with a clinical infection.  These stones can, in some cases, reach a considerable development in the excretory cavities of the kidney, from where the name of coralliform stones. The frequency of straghorm varies from 19 to 54% in childhood urolithiasis;  we found 8.3% of it and they were associated with urinary tract infections in 38.5% of cases. The presence of whewellite in 53.8% of coralliform stones agrees with the results described by several authors who found a primary metabolic cause associated to it, mainly made up by the hypercalciuria,  which was not confirmed by our analyses.
In children with renal calculi, the aims of management should be complete clearance of stones, preservation of renal function and prevention of recurrence. In 167 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 and calculi, and essentially to the rarity of equipment for lithotripsy and endourology in most pediatric surgical units. 
| Conclusion|| |
The male prevalence of pediatric urolithiasis is less obvious in Tunisia. The epidemiological profile of renal stones in our country has changed towards a predominance of calcium oxalate stone and upper tract location. The persistence of urate stones reflects particular eating habits and infectious risk factors specific to rural population. The persistence of endemic urolithiasis in our area reflects a slower progress of the standard of living in our country.
| References|| |
|1.||Angwafo FF 3rd, Daudon M, Wonkam A, Kuwong PM, Kropp KA. Pediatric urolithiasis in sub-saharian Africa: A comparative study in two regions of Cameroon. Eur Urol 2000;37:106-11. |
|2.||Kamoun A, Zghal A, Daudon M, Ben Ammar S, Zerelli L, Abdelmoula J, et al. La lithiase urinaire de l'enfant: contributions de l'anamnθse, de l'exploration biologique et de l'analyse physique des calculs au diagnostic ιtiologique. Arch Pediatr 1997;4:629-38. |
|3.||Kamoun A, Daudon M, Abdelmoula J, Hamzaoui M, Chaouachi B, Houissa T, et al. Urolithiasis in Tunisian children: a study of 120 cases based on stone composition. Pediatr Nephrol 1999;13:920-5. |
|4.||Pietrow PK, Pope JC 4th, Adams MC, Shyr Y, Brock JW 3 rd . Clinical out come of pediatric stone disease. J Urol 2002;167:670-3. |
|5.||Nahlovsky J, Farhat M, Gharbi S. Extraordinary incidence of lithiasis in children in Tunisia and their probable causes. J Urol Nephrol 1969;75:539-41. |
|6.||Najjar MF, Najjar F, Boukef K, Oueslati A, Memi J, Bechraoui T. La lithiase infantile dans la rιgion de Monastir ιtude clinique et biologique. Le Biologiste 1986;165:31-9. |
|7.||Jungers P, Daudon M, Conort P. Lithiase rιnale, diagnostic et traitement. Paris: Flammarion Mιdecine-Sciences, 1999. |
|8.|| Ali SH, Rifat UN. Etiological and clinical patterns of childhood urolithiasis in Iraq. Pediatr Nephrol 2005;20:1453-7. |
|9.||Van Kote G, Lottmann H, Fremond B, Mourey E, Dore B, Daoud S, et al. Lithotritie urinaire de l'enfant. Etude multicentrique du Groupe d'Etudes en Urologie Pιdiatrique (GEUP). Ann Urol (Paris) 1999;33:308-14. |
|10.||Kamoun A, Daudon M, Kabaar N, Dhaoui R, Ben Ammar S, Zghal A, et al. Facteurs ιtiologiques de la lithiase urinaire de l'enfant en Tunisie. Prog Urol 1995;5:942-5. |
|11.||Jungers P, Rieu P, Mιria P, Knebelmann B, Daudon M. Lithiase d'infection. L'Eurobiologiste 2001;254:23-8. |
|12.||Sternberg K, Greenfield SP, Williot P, Wan J. Pediatric stone disease: An evolving experience. J Urol 2005;174:1711-4. |
|13.||Coward RJ, Peters CJ, Duffy PG, Corry D, Kellett MJ, Choong S, et al. Epidemioloy of paediatric renal stone disease in the UK. Arch Dis Child 2003;88:962-5. |
|14.||Al-Eisa AA, Al-Hunayyan A, Gupta R. Pediatric urolithisis in Kuwait. Int Urol Nephrol 2002;33:3-6. |
|15.||Daudon M, Jungers P. Epidιmiologie de la lithiase urinaire. L'Eurobiologiste 2001;253:5-15. |
|16.||Stapleton FB. Childhood stones. Endocrinol Metab Clin N Am 2002;31:1001-5. |
|17.||Oussama A, Kzaiber F, Mernari B, Semmoud A, Daudon M. Analyse de la lithiase de l'enfant dans le moyen Atlas Marocain par spectromιtrie infrarouge. Ann Urol 2000;34:384-90. |
|18.||Daudon M. Comment analyser un calcul et comment interprιter le rιsultat. L'Eurobiologiste 1993;203:35-46. |
|19.||Rizvi SA, Naqvi SA, Hussain Z, Shahjehan S. Renal stones in children in Pakistan. Br J Urol 1985;57:618-21. |
|20.||Bennani S, Debbagh A, Oussama A, el Mrini M, Benjelloun S. Spectrophotomιtrie infrarouge et lithiase urinaire. ΐ propos de 80 cas. Ann Urol 2000;34:376-83. |
|21.||Alaya A, Nouri A, Najjar MF. Paediatric renal stone disease in Tunisia: A 12 years experience. Arch Ital Urol Androl 2008;80:50-5. |
|22.||Alaya A, Belgith M, Jouini R, Nouri A, Najjar MF. La lithiase urinaire de l'enfant en Tunisie. Aspects actuels ΰ propos de 104 cas. Prog Urol 2006;16:474-80. |
|23.||Daudon M, Bounxouei B, Santa Cruz F, Leite da Silva S, Diouf B, Angwafoo FF 3 rd , et al. Composition des calculs observιs aujourd'hui dans les pays non industrialisιs. Prog Urol 2004;14:1151-61. |
|24.||Jallouli M, Jouini R, Sayed S, Chaouachi B, Houissa T, Ayed M, et al. Pediatric urolithiasis in Tunisia: A multi-centric study of 525 patients. J Pediatr Urol 2006;2:551-4. |
|25.||Daudon M. L'analyse morphoconstitutionnelle des calculs dans le diagnostic ιtiologique d'une lithiase urinaire de l'enfant. Arch Pediatr 2000;7:855-65. |
|26.||Benchekroun A, Lachkar A, Iken A, Ghadouan M, Ben Sliman L, Belahnech Z, et al. La lithiase coralliforme. ΐ propos de 98 cas. Ann Urol (Paris) 2000;34:370-5. |
|27.||Faure G, Sarramon JP. Staghorn coral-type calculi. J Urol 1982;88: 409-501. |
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]