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Idiopathic hypercalciuria of childhood: 4- to 11-year outcome
1Section of Pediatric Nephrology, The Children's Mercy Hospital, University of Missouri at Kansas City, 64108, USA. ualon@cmh.edu
Insights
Many children with idiopathic hypercalciuria become asymptomatic but remain hypercalciuric. Long-term follow-up is needed to assess kidney stone risk, and a low-sodium/high-potassium diet may help normalize calcium levels.
Area of Science:
- Pediatric Nephrology
- Urology
- Metabolic Disorders
Background:
- Idiopathic hypercalciuria in children often presents with hematuria, pain, or voiding symptoms.
- Most children become asymptomatic with treatment but long-term outcomes are largely unknown.
- This study investigates the long-term status of children diagnosed with idiopathic hypercalciuria without urolithiasis.
Purpose of the Study:
- To evaluate the long-term clinical and biochemical status of children with idiopathic hypercalciuria.
- To determine the persistence of hypercalciuria and the risk of developing urolithiasis.
- To assess the impact of dietary interventions on urinary calcium and sodium/potassium ratios.
Main Methods:
- Retrospective analysis of 33 children (14 males, 19 females) aged 8-17 years, 4-11 years post-diagnosis.
- Analysis of two urine samples for calcium, sodium, potassium, and creatinine to assess hypercalciuria (Ca/Cr ratio ≥ 0.21 mg/mg).
- Questionnaires, ultrasonography, and assessment of dietary intervention effects (low-Na/high-K diet).
Main Results:
- 48.4% of children remained hypercalciuric upon re-evaluation.
- No child developed clinical urolithiasis; one asymptomatic child had a small renal calcification.
- A low-sodium/high-potassium diet normalized calciuria and reduced urinary sodium/potassium ratios in persistently hypercalciuric children.
Conclusions:
- Despite becoming asymptomatic, a significant proportion of children with idiopathic hypercalciuria remain hypercalciuric long-term.
- Further follow-up is crucial to identify children at risk for kidney stone formation.
- A low-sodium/high-potassium diet shows promise in managing hypercalciuria and potentially preventing urolithiasis.
Abstract:
Apart from a minority with urolithiasis, the majority of children diagnosed with idiopathic hypercalciuria present with macro- or microhematuria, abdominal or back pain, or voiding symptoms. With dietary and pharmacological interventions, most such children become asymptomatic and are lost to follow-up, hence their long-term outcome is unclear. In the present study, we evaluated the status of 14 males and 19 females aged 8-17 years (mean 11.9 years, median 11.2 years) 4-11 years (mean 6.9 years, median 6.5 years) after the initial diagnosis of idiopathic hypercalciuria not associated with urolithiasis. A questionnaire was answered and two random urine samples provided 3-4 weeks apart were analyzed for calcium (Ca), sodium (Na), potassium (K), and creatinine (Cr). Urine Ca/Cr ratio > or =20.21 (mg/mg) was defined as hypercalciuria. At the time of the study none were under follow-up, although 7 children were still exhibiting voiding symptoms. No child developed clinical urolithiasis. Based on the first urine specimen, 16 of the 33 (48.4%) were hypercalciuric. Their 2nd urinalysis showed persistent hypercalciuria in 8 and normocalciuria in 8. Urine Na/K ratio (mEq/mEq) decreased in the latter 8 from 5.08+/-2.67 to 3.03+/-2.23 (P<0.05). Of the 17 initially normocalciuric children, 5 did not submit a 2nd specimen, 11 remained normocalciuric, and 1 became hypercalciuric with an increase in urine Na/K ratio. Twenty-three children (all 8 persistently and 9 intermittently hypercalciuric plus 6 normocalciuric) were studied by ultrasonography. Only in 1 asymptomatic persistently hypercalciuric child was a single small renal calcification noted. Introduction of a low-Na/high-K diet in 7 persistently hypercalciuric children resulted in a decrease in UNa/K ratio from 7.34+/-2.15 to 4.14+/-3.09 (P<0.01) and UCa/Cr ratio from 0.25+/-0.04 to 0.13+/-0.03 (P<0.01). We conclude that even though over time most hypercalciuric children become asymptomatic, many remain hypercalciuric. Further follow-up is required to ascertain whether these children are at risk of developing kidney stones. If they are at risk then long-term compliance with a low-Na/high-K diet might be beneficial, as it can normalize calciuria in the majority of these children.