Metabolic risk factors in children with kidney stone disease: an update

Cystinuria Complicated by Anuria From Bilateral Obstructing Stones Requiring Bilateral Mini Percutaneous Nephrolithotomy in a 22-Month-Old

Pediatric nephrolithiasis is increasing in incidence and presents differently compared to adults. We report a case of nephrolithiasis in a pediatric patient, presenting with complaints of emesis, anuria, hematuria, and abdominal distension, leading to a diagnosis of bilateral obstructing cystine stones requiring bilateral percutaneous nephrolithotomy. Pediatric patients with anuria should be evaluated for bilateral nephrolithiasis as an etiology. Calculous anuria requires prompt recognition of the pathologic process and relief of the obstruction with close follow-up and supportive care until definitive stone management. Bilateral percutaneous nephrolithotomy can provide definitive surgical intervention without significant morbidity.

Urolithiasis in children; The importance of stone localization in treatment and follow-up

To evaluate the demographic, etiologic, treatment, and follow-up differences in stones according to their location within the kidney. This retrospective study comprised 337 patients with urolithiasis between 2015 and 2019. Patients were classified into 2 groups according to stone location as lower pole stones (LPS) and upper-middle pole stones (UMPS). The patient's data were recorded at 3-month intervals for one year. One hundred and eighty-three (54.3%) female and 154 (45.7%) men were included in the study. One hundred and twenty-nine (38.3%) of the stones were in the LPS and 208 (61.7%) in the UMPS. UMPS was more common in patients aged > 12 months (p < 0.01). At least one metabolic risk factor was present in 93 (72.1%) patients with LPS and 164 (78.4%) with UMPS. The most common urinary metabolic risk factors were hyperoxaluria (31.8%) in patients with LPS and hypocitraturia (34.1%) in patients with UMPS. ROC analysis results showed that cut-off values of 5.5 mm for LPS and 6.1 mm for UMPS did not provide improve with medical treatment. At the 6- and 12-month follow-ups, the improvement rates were higher in the UMPS group than in the LPS group (p < 0.05). During the follow-up, recurrence was detected in 43 patients: 29% of patients with LPS and 5.8% of patients with UMPS (p < 0.01). Patients with small stones can be followed up. Surgical treatment may be considered for small stones in the LPS. In addition, the risk of recurrence is higher in patients with LPS, and close follow-up is required.

Metabolic and Genetic Evaluation in Children with Nephrolithiasis

OBJECTIVE

To evaluate metabolic and genetic abnormalities in children with nephrolithiasis attending a referral center in North India.

METHODS

The patients aged 1-18 y old with nephrolithiasis underwent biochemical evaluation and whole-exome sequencing. The authors evaluated for monogenic variants in 56 genes and compared allele frequency of 39 reported polymorphisms between patients and 1739 controls from the GenomeAsia 100 K database.

RESULTS

Fifty-four patients, aged 9.1 ± 3.7 y were included. Stones were bilateral in 42.6%, familial in 33.3%, and recurrent in 25.9%. The most common metabolic abnormalities were hypercalciuria (35.2%), hyperoxaluria (24.1%), or both (11.1%), while xanthinuria (n = 3), cystinuria (n = 1), and hyperuricosuria (n = 1) were rare. Exome sequencing identified an etiology in 6 (11.1%) patients with pathogenic/likely pathogenic causative variants. Three variants in MOCOS and one in ATP7B were pathogenic; likely pathogenic variants included MOCOS (n = 2), AGXT, and SLC7A9 (n = 1, each). Causality was not attributed to two SLC34A1 likely pathogenic variants, due to lack of matching phenotype and dominant family history. Compared to controls, allele frequency of the polymorphism TRPV5 rs4252402 was significantly higher in familial stone disease (allele frequency 0.47 versus 0.53; OR 3.2, p = 0.0001).

CONCLUSION

The chief metabolic abnormalities were hypercalciuria and hyperoxaluria. A monogenic etiology was identified in 11% with pathogenic or likely pathogenic variants using a gene panel for nephrolithiasis. Heterozygous missense variants in the sodium-phosphate cotransporter SLC34A1 were common and required evaluation for attributing pathogenicity. Rare polymorphisms in TRPV5 might increase the risk of familial stones. These findings suggest that a combination of metabolic and genetic evaluation is useful for determining the etiology of nephrolithiasis.

Do dietary factors play a role in infantile urolithiasis?

BACKGROUND

Urolithiasis is a significant cause of morbidity that may be diagnosed at a young age. However, there is little research on the role of nutrition in pediatric urolithiasis, and research on the infantile period is extremely rare. The aim of this study is to investigate the effect of dietary factors on those diagnosed with "idiopathic" infantile urolithiasis.

METHOD

The study group included 44 infants without a proven etiological factor for urolithiasis. The control group consisted of 60 fully healthy infants of matched age and gender. The parents and caregivers of each infant in the patient and control groups were carefully questioned by the same researcher for their dietary characteristics.

RESULT

The duration of formula usage and daily volume of formula were statistically higher in the study group than the control group (p = 0.041 and p = 0.003, respectively). The urolithiasis group consumed significantly more cow's milk and dairy products (p = 0.033 and p = 0.001). There was no statistically meaningful difference between the two groups in terms of starting age for free water and salty food, as well as daily water intake.

CONCLUSION

We concluded that dietary conditions could also be a risk factor for idiopathic urolithiasis. We believe that nutritional factors for infantile urolithiasis should be better described, in addition to genetic, anatomical, and metabolic factors. A higher resolution version of the Graphical abstract is available as Supplementary information.