Urology Annals

ORIGINAL ARTICLE
Year
: 2009  |  Volume : 1  |  Issue : 2  |  Page : 52--55

Hypercalciuria, a promoting factor to urinary tract infection in children


Alaleh Gheissari1, TajSaadat Adjoodani1, Peyman Eshraghi2,  
1 Department of Pediatric Nephrology, St Al-Zahra Hospital, Isfahan University of Medical Sciences, Iran
2 Department of Endocrine and Metabolism, Amirkola Children Hospital, Babol Medical University, Iran

Correspondence Address:
Alaleh Gheissari
Department of Pediatric Nephrology, St Al-Zahra Hospital, Isfahan University of Medical Sciences
Iran

Abstract

Aim: Urinary tract infection (UTI) is one of the most common diseases of urogenital tract in children. Detecting predisposing factors for UTI takes an important place in managing patients with UTI. Recently, a few studies emphasized on idiopathic hypercalciuria (IH) as a predisposing factor for UTI and dysfunctional voiding. Therefore, we carried out a survey to find out whether non-calculus IH is a contributing factor in children with the first attack of pyelonephritis. Materials and Methods: This is a case-control study carried out on 60 children aged 2-11 years admitted at St Al-Zahra hospital, Isfahan, Iran, with the first episode of upper UTI and 200 age- and gender-matched normal healthy children between September 2003 and February 2005. We used second fasting spot urine sample to measure calcium and creatinine. Two urine samples were obtained one week apart to increase the accuracy of measurement. All samples were collected after at least 6 weeks of completing the treatment course of pyelonephritis. Ultrasound examination and VCUG were performed in all patients before entering the survey as case group to rule out obstruction and VUR. Results: Mean age of case and control group were 4.86 ± 3.08 years and 4.22 ± 2.9 years, respectively. The mean calcium to creatinine ratio (Ca/Cr) in case and control group were 0.308 ± 0.21 and 0.208 ± 0.12 mg/mg, respectively, P < 0.001. The difference between the mean values of these two groups was significant only in age group ≤6 years, P < 0.0001 and odds ratio was 2.1 (95% CI 1.03-7.8). After determining the mean values of urine Ca/Cr ration according to both age groups and gender, it was cleared that only significant difference was related to male <6 years. Conclusion: The likelihood of hypercalciuria should be assessed especially in male children with UTI and without any urinary tract obstruction.



How to cite this article:
Gheissari A, Adjoodani T, Eshraghi P. Hypercalciuria, a promoting factor to urinary tract infection in children.Urol Ann 2009;1:52-55


How to cite this URL:
Gheissari A, Adjoodani T, Eshraghi P. Hypercalciuria, a promoting factor to urinary tract infection in children. Urol Ann [serial online] 2009 [cited 2020 Aug 8 ];1:52-55
Available from: http://www.urologyannals.com/text.asp?2009/1/2/52/56046


Full Text

[±±±TAG:2]Introduction



Urinary tract infection (UTI) is one of the most common diseases of urogenital tract in children. About 3-5% of girls and 1% of boys experience at least one episode of UTI during childhood. [1] Kidney scar due to UTI is an etiology for developing hypertension and various degrees of renal functional impairment. Therefore, detecting predisposing factors for UTI takes an important place in managing patients with UTI. Vesicoureteral reflux (VUR), voiding dysfunction, urinary tract obstruction (UTO), poor hygiene and anatomical abnormalities are some of the known predisposing factors for developing UTI. However, a substantial number of these patients develop recurrent episodes of UTI without a clear evidence of these known risk factors. Recently, a few studies emphasized on idiopathic hypercalciuria (IH) as a predisposing factor for UTI and dysfunctional voiding. [2],[3],[4],[5],[6] Some of these studies have been conducted on patients with recurrent UTI and or urinary tract anatomical abnormalities. On the other hand, idiopathic hypercalciuria is a common finding among referral patients to pediatric nephrologists' offices with chief complaints related to urinary tract other than UTI. Therefore, we carried out a survey to find out whether non-calculus IH is a contributing factor in children with the first attack of pyelonephritis.

 Materials and Methods



This is a case-control study carried out on 60 children aged 2-11 years admitted at St Al-Zahra hospital, Isfahan, Iran, with the first episode of upper UTI and 200 age- and gender-matched normal healthy children between September 2003 and February 2005. The sampling method was non-probability convenience sampling. We performed the study on children with first episode of pyelonephritis and without urinary tract abnormalities and/or stones. The likelihood of disease was compared between the two groups.

Inclusion criteria for case group:

1. Children between 2 and 11 years of age.

2. No evidence or past history of kidney stone, urinary tract obstruction and moderate-to-high-grade reflux (low-grade reflux might be under-diagnosed by standard Voiding Cystourethrogram, VCUG)

3. Proven pyelonephritis; diagnosis was made on:

Positive clean-catch or catheter specimens voiding (colony counts more than 100 000 colonies/ml for clean-catch voiding and more than 10 000 colonies/ml for catheter specimen voiding were considered as positive cultures)Oral temperature >38.5˚C, or rectal temperature >39˚C for children under 5 years plus at least one of the following signs or symptoms: Abdominal painDysuriaUrinary frequencyUrinary urgencyFlank pain and or tendernessAnd at least one of the following paraclinical findings:Quantitative C-reactive protein (CRP) more than 0.5 mg/dlHigh erythrocyte sedimentation rate (ESR >30 mm/hr)Low urine specific gravity regarding the patients' hydration

To avoid excessive exposure to radiation, Dimercaptosuccinic acid (DMSA) as diagnostic tool was performed in a small number of patients with a low colony count of microorganisms and or confusing signs and symptoms.

4. Negative urine culture at the time of measuring urine calcium and creatinine and at least 6 weeks after completing the treatment course of pyelonephritis.

5. No documented history of previous UTI.

6. Normal venous blood gas and serum calcium.

7. No history of recent consumption of loop and thiazide diuretics.

We used second fasting spot urine sample to measure calcium and creatinine. Two urine samples were obtained one week apart to increase the accuracy of measurement. All samples were collected after at least 6 weeks of completing the treatment course of pyelonephritis and achieving two consecutive negative cultures in case group. We used adjusted Ca/Cr ratios (mg/mg) (95 th percentile for age) as follows: [7]



Age 19 months to 6 years 0.42Age >6 years 0.22

Regarding the age groups mentioned above, patients were divided into two groups: between 2-6 years and more than 6 years up to 11 years.

Urine calcium (uCa, mg/dl) and serum creatinine (sCr, mg/dl) were determined by cresolphthalein and Jaffe method, respectively.

Ultrasound examination and VCUG were performed in all patients before entering the survey as case group to rule out UTO and VUR.

Data was analyzed by SPSS 15 software. To assess risk estimation, odds ratio (95% confidence interval) was used. Considering confounding factors, such as age and gender, we used the Mantel-Haenszel method.

 Results



Mean age of case and control group were 4.86 ± 3.08 years and 4.22 ± 2.9 years, respectively. Approximately 83% of case and 58% of control group were female (about 63% of all participants). The mean calcium to creatinine ratio (Ca/Cr) in case and control group were 0.308 ± 0.21 and 0.208 ± 0.12 mg/mg, respectively, P [3],[5],[6] A few researches emphasized on the role of hypercalciuria in producing UTI. [2],[4],[8],[9] However, most of these studies were carried out on children with a history of recurrent UTI, abnormalities of urinary tract, urinary tract stones and or dysfunctional voiding. Different mechanisms have been shown as responsible mechanism for UTI, such as uroepithelial damage by calcium oxalate monohydrate, the balance between bacterial virulence and host resistance, an inflammatory response to lipopolysaccharide (LPS) and low urinary secretory IgA (sIgA). [10],[11],[12],[13] Hypercalciuria can predispose patients to UTI due to uroepithelial damage. Akil et al., showed that hypercalciuric rats revealed proliferation and apical cytoplasmic vacuole formation in transitional epithelial cells of bladder and ureter specimens, and also vacuolization of proximal and distal tubules, tubular degeneration, interstitial edema and vasodilatation of the kidney. [10] According to Vachvanichsanong et al., decreasing urinary calcium excretion was associated with decreased symptoms of dysfunctional voiding. [6] Kaminska et al., showed that treatment of pre-urolithiasis state could decrease the recurrence rate of UTI. [8]

The prevalence of idiopathic hypercalciuria is different among various populations; from as low as 0.6% in Japanese to as high as 17.6% in white Americans. [14],[15]

A recent study conducted in Tehran, Iran, showed a prevalence of 5.4% among school-age children. [5]

We found that idiopathic hypercalciuria without any other UTOs could increase the chance of UTI in children less than 6 years of age up to 2.1 times compared to the control group. However, this increment was significant only in male patients. As UTI is not a common disease in male after first year of life, the likelihood of hypercalciuria should be assessed especially in male children with UTI and without any UTOs.

However, the inadequacy of patients in each age-group was the shortage of our study. We recommend more research on larger groups and even longitudinal follow-up studies to clarify the exact role of hypercalciuria in inducing UTI.

 Acknowledgments



We would like to express our gratitude to Dr. Ziba Farajzadegan for analyzing our data.

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