Daughter is athlete,lean,great physical shape.she has been fatigued,tired walking up stairs&exercise.rhr90.blood norm.bring to pediatric card? shes18

Start with family MD: A number of things cause fatigue and tiredness that are not cardiac that can be identified by an exam and simple lab tests, so start with a visit to her primary care doctor, pediatrician or family doctor. Most common would be anemia, mono, or thyroid condition. It would be unlikely for a cardiac problem to manifest this way at age 18.