My son who is now 6 and half years since more than two years once or twice a year he has 100 per cent blood in urine. When we give him water within an hour it will come to normal .We experienced when he has taken less water it happens. We have done all the related test and even genetic test. But all the reports are normal. Even yesterday he started having blood in urine but stop within 1 hour by drinking water. Please advise us what may be the causes and its prevention. Till now nothing can be diagnosed.