Fact: The majority of Dysautonomia patients- specifically POTS patients- are hypovolemic, despite adequate hydration. Standard blood and urine tests may not always detect this hypovolemia, as the patient is typically deficient in plasma and red blood cells. Blood volume analysis with a radio-tracer can be used to evaluate a POTS patient for hypovolemia (Dysautonomia International).
Hypovolemia, or low blood volume, is a daily struggle for me. In order to combat this issue, I receive two to four liters of IV Saline each week, as well as push a liter or more of water and Pedialyte through my j-tube each day.