Bartter syndrome type 3, also known as classic Bartter syndrome, is a rare disorder that affects a person’s kidneys, the organ that filters our blood. People affected by Bartter syndrome do not have the right amount of potassium and magnesium (elements the body needs for nutrition) in their kidneys, causing the person’s body to get rid of potassium, magnesium, and calcium. Since the person’s body is getting rid of the nutrients it needs (potassium, magnesium, and calcium), the person will have low levels of these nutrients. In addition to having low potassium, magnesium, and calcium levels, the person affected by Bartter syndrome may have low blood pressure and more basic (rather than acidic) blood. Diagnosis for Bartter syndrome usually occurs when children are in elementary school, although some children are diagnosed as young as 2-3 years old. Talk with your doctor to find the best treatment if your child has been diagnosed with Bartter syndrome type 3.