Research News

Diet Alone Is Not Enough to Improve Bone Strength in Children with Idiopathic Hypercalciuria

Dietary modifications may be sufficient to decrease kidney stones in children with idiopathic hypercalciuria, but they are not enough to improve their bone mineral density, according to a Nationwide Children’s Hospital study appearing in Clinical Nephrology. 

Kidney stones have increased dramatically in children over the last decade.   Most children who have kidney stones have high urine calcium, known as hypercalciuria, as a contributing risk factor.  Over a third of kidney stone patients with high urine calcium have also recently been shown to have low bone density.  
Children with idiopathic hypercalciuria are initially treated with dietary modifications including increased fluid intake, recommended daily allowance for protein and calcium and avoidance of excessive sodium and oxalate.  These approaches are primarily meant to decrease urinary calcium excretion and improve symptoms such as frequency and urgency to urinate.   Children who remain symptomatic are often prescribed diuretics or dietary supplements.   
Studies have suggested a link between hypercalciuria and low bone mineral density.  However, the natural history of bone mineral density in children with this condition and its response to therapy has not been evaluated. 
“It is essential to know which factors influence bone mineral density in childhood,” said Andrew L. Schwaderer, MD, pediatric nephrologist in Nephrology at Nationwide Children’s and study author.  “Bone formation occurs in childhood and peaks in late adolescence.  Any condition that impairs bone development by young adulthood is a significant risk factor for osteoporosis later in life.” 
To better understand bone mineral density patterns in children with hypercalciuria, Dr. Schwaderer with Nationwide Children’s Principal Investigator David Hains, MD, and colleagues performed a retrospective review of patients seen in the Pediatric Nephrology Clinic at Nationwide Children’s during an 8 year period.  Participants were categorized into two groups, those who received only dietary recommendations and others who were treated both with dietary recommendations and oral potassium citrate therapy.  
Investigators found that the mean lumbar bone density scores per-year decreased in the diet-only group, suggesting that children with hypercalciuria lose bone mineral density over time.  The group that made dietary changes and used potassium citrate increased their bone mineral density measures each year.  This is the first study to report the natural history of bone mineral density in children with hypercalciuria. 
“Our findings suggest that standard dietary recommendations alone do not alter the natural history of lumbar bone mineral density, and additional intervention with potassium citrate may have a potential positive impact on bone mineral density,” said Dr. Hains. 
Drs. Hains and Schwaderer emphasize that large, prospective studies are needed before dietary and therapy changes impacting bone mineral density in pediatric hypercalciuria be officially recommended. 
Schwaderer AL, Srivastava T, Schueller L, Cronin R, Mahan JD, Hains D. Dietary modifications alone do not improve bone mineral density in children with idiopathic hypercalciuria. Clin Nephrol. 2011 Nov;76(5):341-7.

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