There is a medical condition where children develop a maple syrup odor to their urine. Children with this rare disorder usually have many other symptoms in early infancy like vomiting, lethargy, low muscle tone, and seizures so it is unlikely that a healthy three year old would have this disorder. Many states screen all newborns for this disorder. Sometimes people with diabetes develop an odor to their breath when their sugar level is out of control. Again, this would be unusual in a child without other symptoms such as increased urine output, increased desire to drink, weight loss, and abnormal breathing.
Most likely there is nothing concerning about the odor but anytime you have concerns about your child, especially if they are persistent over time, it is best to have your child evaluated by their doctor. At the visit be honest about what your concerns are and what you have read on the internet or heard from friends. The more your physician understands about your worries the better they can help evaluate your child and reassure you as to whether or not any further testing needs to be done.
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