Comparison of Risk Factors for Pediatric Kidney Stone Formation: The Effects of Sex

Abstract

Background: Urinary stones are affecting more children, and pediatric stone formers have unique pathophysiology compared to adults. While adult stone formers are most frequently male, children have an age dependent sex prevalence. Under 10 years, a majority of stone formers are boys; adolescent stone formers are mostly female. Previous adult studies have shown that stone composition is influenced by the sex and age of the stone former. Thus, we hypothesize that female and male stone forming children will also have sex and age specific stone phenotypes. Methods: Retrospective chart review of a large pediatric center's stone forming children 6/1/2009 to 6/1/2016. Patients were identified by ICD 9 codes: N20, N20.1, and N20.9. Charts were reviewed for radiographic evidence of stones or documented visualized stone passage. Results: One hundred and thirty six subjects: 54 males and 82 females. Females were older, median age 14 years [interquartile range (IQR): 11, 15] vs. males' median age 12 years (IQR: 11, 14) ( p < 0.01). Females had lower height z -scores, median 0.2 (IQR: −0.8, 0.8) vs. males' median 0.8 (IQR: −0.2, 1.8) ( p < 0.01). Presenting symptoms were similar except flank pain affecting 39% of females vs. 22% of males ( p = 0.04). Leukocyte esterase was positive in more females than males (33 vs. 4%) ( p < 0.001). Males had a higher BUN/Cr ratio, mean ± standard deviation of 19.8 ± 6.3 vs. 16.6 ± 6.5 in females ( p = 0.01). Glomerular hyperfiltration was present in 9% of patients while 35% of patients had estimated glomerular filtration rate (eGFR) < 90 ml/min/1.73 m 2 . Treatment strategies and clinical course were similar except females were told to increase dietary citrate more frequently than males (21 vs. 4%) ( p < 0.01). Conclusion: We have provided a novel analysis and demonstrated that low height z -score and pyuria are more common in female stone formers. We have also shown that 9% of pediatric stone formers have labs consistent with hyperfiltration. Whether high protein intake and/or chronic dehydration are associated with hyperfiltration and long-term renal function in children with kidney stones will be an area for future research.

Gender Differences in Kidney Stone Disease (KSD): Findings from a Systematic Review

“…Furthermore, the lifetime risk of developing KSD among females increased by 45% during the study period (1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012). Both this study and one by Schwadrerer et al recorded that girls were most likely to experience KSD in adolescence [42,43]. This age group is increasingly affected by KSD which is consistent with findings from NHNES [10].…”

“…A large contributing factor for this is considered to be the paralleled rise of body mass index (BMI) in this age group [41]. Three studies were identified, which investigated gender differences in paediatric KSD [42][43][44]. Taisan et al reported findings from a longitudinal study over a 30-year period and found the overall risk of KSD doubled in children [42].…”

Comparing Nephrolithiasis with Nephrocalcinosis in Children; A Study From Two Tertiary Centers in Saudi Arabia

“…The clinical outcome of kidney disease in children is poorly understood. According to a recent report, male and female patients have similar hospitalization rates and frequency of stone episodes [23]. In an older study that attempted to investigate clinical outcomes in children with urolithiasis, the investigators were unable to comment on the outcome of urolithiasis in their patients [21].…”

Double obstruction of upper and lower urinary tract in a child due to renal stone disease: Endoscopic treatment

“…The diagnosis of RSD in children has doubled from 7.2 to 14.5/100,000 person-years in the past 2 to 3 decades. [3,4] Colicky abdominal pain is the most common presentation of stone disease (50-80%) followed by non-specific abdominal pain and gross hematuria in 30-50% children. Lower urinary tract symptoms such as frequency, urgency and dysuria, urinary tract infection, urinary retention in case of stone obstructing the urethra, and passage of stones are the other common presentations.…”