Kidney stones are solid crystal aggregates of minerals that pass through the urinary tract. They may cause no symptoms if they are small. Larger stones cause pain in the back or side radiating to the groin. Causes of urinary stones in children include structural problems in the urinary tract, urinary tract infections and metabolic disorders.
Structural Problems
Structural problems in the kidneys or urinary tract promote urinary stasis by obstructing the flow of urine. This predisposes towards the formation of kidney stones. In polycystic kidney disease, the kidneys contain many hollow, cavernous spheres called cysts that interfere with urine flow, leading to stone formation. Another example is ureteropelvic junction obstruction in which there is an obstruction between the kidney and ureters, the tubes leading to the bladder.
Urinary Tract Infections
Urinary tract infections are more common in children than adults, and infections with certain bacteria can lead to kidney stone formation. According to "Pediatric Urology" by John G. Gearhart, M.D., these bacteria include Proteus, Klebsiella, Psuedomonas and a few others. They produce an enzyme called urease which predisposes children to developing large stones composed of magnesium, ammonium and phosphate called struvite stones.
Metabolic Disorders
Metabolic disorders can cause high concentrations of stone forming minerals or low concentrations of chemicals that inhibit stone formation. High calcium levels in the urine are the most common metabolic problem. Citrate inhibits calcium stone formation, low levels of citrate in the urine lead to stone formation as well.
References
- "Pediatric Urology"; John G. Gearhart; 2nd Ed 2009
- "Harrison's Principles of Internal Medicine"; Anthony Fauci et al; 17th Ed 2008
