Kidney stones are solid, pebble-like masses that form in the kidneys when high levels of certain minerals occur in urine. While commonly associated with adults, kidney stones can affect children of all ages. These formations vary in size, from a grain of sand to, in rare instances, the size of a golf ball.
Understanding Pediatric Kidney Stones
Pediatric kidney stone occurrence has increased notably in recent decades, with some reports showing a 4% to 10% annual rise. This trend highlights a shift from what was once primarily an adult condition. Though still less common in children, their growing prevalence is a significant public health concern. The majority of kidney stones found in children are calcium-based, such as calcium oxalate or calcium phosphate stones. Less frequently, stones can be composed of uric acid, cystine, or struvite.
Causes and Risk Factors in Children
Multiple factors contribute to kidney stone formation in children, including metabolic, genetic, dietary, and medical influences. Metabolic abnormalities are a primary cause, including hypercalciuria (excess calcium in urine) and hypocitraturia (low citrate levels). Other issues include hyperoxaluria (high oxalate levels) and cystinuria, an inherited disorder causing excess cystine. Genetic predispositions also play a role, as children with a family history of kidney stones have an increased likelihood of developing them.
Dietary habits significantly influence stone formation. Insufficient fluid intake, leading to concentrated urine, is a common factor. Diets high in sodium can increase calcium levels, while excessive protein intake may elevate uric acid and calcium, simultaneously reducing stone-inhibiting citrate. Conversely, not consuming enough calcium can paradoxically increase the risk of calcium oxalate stones by raising oxalate levels.
Certain medical conditions and medications can also contribute. These include urinary tract infections, structural abnormalities of the urinary tract, and conditions causing chronic diarrhea, such as inflammatory bowel disease. Some medications like diuretics, calcium-based antacids, and certain seizure drugs can also increase stone risk.
Recognizing Symptoms and Diagnosis
Recognizing kidney stone symptoms in children can be challenging, as they vary depending on the child’s age and the stone’s location. Older children and teenagers may experience sharp, intense pain in the back, side, lower abdomen, or groin, which can come and go in waves. Nausea, vomiting, and blood in the urine (hematuria), which may appear pink, red, or brown, are common indicators. Some children might report a constant need to urinate or pain during urination. In infants and young children, symptoms are less specific and may include irritability, unexplained fever, or general abdominal pain.
Diagnosis involves a physical examination and a review of the child’s medical history. Laboratory tests, such as urinalysis, can detect blood, infection, and high levels of stone-forming minerals. A 24-hour urine collection may also be performed to measure various substances that contribute to stone formation.
Imaging techniques are crucial for confirming a diagnosis and determining stone characteristics. Ultrasound is the preferred initial imaging choice due to its non-invasive nature and lack of radiation exposure. If more detailed information is needed, an abdominal X-ray or a computed tomography (CT) scan may be used, though CT scans involve radiation and are reserved for cases where ultrasound is inconclusive.
Treatment Approaches for Children
Treatment for pediatric kidney stones is individualized, considering the stone’s size, location, composition, and the child’s overall health, with an emphasis on minimizing invasiveness. For small stones, conservative management is sufficient, focusing on increased fluid intake to help the stone pass naturally and pain management. Collecting the passed stone for analysis can help determine its composition and guide future prevention strategies.
For larger or symptomatic stones, interventional procedures may be necessary. Extracorporeal shock wave lithotripsy (ESWL) is a non-invasive option that uses shock waves to break stones into smaller fragments that can then be passed. This procedure is a first-line treatment for stones less than 1 cm.
Ureteroscopy involves inserting a thin scope through the urethra and bladder into the ureter or kidney to visualize and remove the stone, or to break it up with a laser. For very large or complex stones, percutaneous nephrolithotomy (PCNL) may be performed. This minimally invasive surgical procedure involves making a small incision in the back to directly access the kidney and remove the stone.
Preventing Recurrence
Preventing kidney stone recurrence is a significant aspect of long-term management for children. Ensuring adequate fluid intake is a primary strategy, as diluted urine helps prevent minerals from crystallizing. Children should drink enough water daily for their urine to be pale or almost colorless. Citrus drinks, like sugar-free lemonade, can also be beneficial due to their citrate content, which inhibits stone formation.
Dietary modifications are important. Limiting sodium intake can reduce calcium excretion, and avoiding excessive animal protein may prevent uric acid and calcium increases. For children prone to calcium oxalate stones, restricting high-oxalate foods like dark chocolate, black tea, and spinach may be advised. Calcium intake should not be restricted unless specifically recommended by a doctor. Ongoing medical follow-up, including regular urine and blood tests, helps monitor metabolic factors and adjust preventive measures.