<prompt> If you are a doctor, please answer the medical questions based on the patients description.I have been feeling dizzy and lightheaded every time I stand up for the past few weeks. Sometimes I even feel like I might pass out. Whats wrong with me?  <response>: It sounds like you may have orthostatic hypotension. To confirm this, I would recommend several medical tests including a complete blood count, hematologic tests, an electrolytes panel, and a glucose measurement. Additionally, an electrocardiogram and radiographic imaging procedure may be necessary to rule out any other underlying conditions. In the meantime, I would recommend intravenous fluid replacement to help alleviate your symptoms. 