Hello I have gone through your question and understand your concern. From your description i can deduct that your child has frequent urination and poliuria.Important element is that he doesn t have excessive fluid intake. My first idea is that the cause can be Vasopressin or ADH deficiency. This condition is calledl diabetes insipidus and it can be central due to hypothalamic or pituitary disorders or nephrogenic due to Resistance to ADH action at the site of renal tubules. Other potential causes are:Diabetes mellitus,Hypercalciuria,renal tubular acidosis,Barter s syndrome. My suggestion for you is to talk with his pediatrician and to start the specific tests for diabetes insipidus and other potential causes,necessary to reach the right diagnose. Second suggestion:Encourage your child to drink extra fluids to prevent dehydration and avoid giving him high-protein foods. Hope this is helpful.If you have other questions,feel free and ask. Take care.