The blood urea nitrogen or BUN is a blood test that measures the amount of urea nitrogen in the bloodstream. It reflects how well your kidneys are. When a person is dehydrated, false results might be obtained as BUN levels increase when blood is concentrated. Elevated BUN levels indicate dehydration, excessive protein intake and impaired renal function. Low BUN levels indicate over hydration, liver damage and malnutrition.
An atrial septal defect allows oxygen-rich (red) blood to pass from the left atrium, through the opening in the septum, and then mix with oxygen-poor (blue) blood in the right atrium. An ostium secundum is an opening in the middle of the atrial septum which is the most common type of ASD. Atrial septal defects occur in 5 to 10 percent of all children born with congenital heart disease. For unknown reasons, girls have atrial septal defects twice as often as boys.