How bad does iron def anemia have to be before it causes heart problems? my hemo is 11 (116) and iron is 8. have chest pain and sob and low bp and dizzyness and restless legs. so sick slways!

Much lower than that: A hemoglobin of 11 is only mildly reduced. Anemia itself will not cause cardiac or more likely issues with oxygen transport until it is much lower. Exactly how low depends on whether there are pre existing cardiovascular issues.

Different levels: Typically in a hospitalized person, i would worry about acute cardiac problem as the hemoglobin (hemo) is significantly less than 10. Iron levels can be very low in some people even 2. The real issue is why the iron problem is there (blood loss, no blood preduction or stuck somewhere in your body). Iron def can causes lots of medical things and med things can cause iron/blood loss. Check it out.