Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Kidney Stones in Children ?
    ### Response:
    Kidney stones can form when substances in the urinesuch as calcium, magnesium, oxalate, and phosphorousbecome highly concentrated due to one or more causes:
                
- Defects in the urinary tract may block the flow of urine and create pools of urine.
    