My 15 yo has abn low hr resting in high 30s. This has been ongoing for years. She has seen a cardiologist and was cleared 3 years ago but recently has become symptomatic with it. She then had an episode of tachycardia up to 130s. Went to ER, EKG showed bradycardia and sinus arrythmia, had lab done, her K+ was 3.2, TSH was 4.8, sodium was 146. CBC fine. The Doc referred her back to cardiology and he drew; reverse T3 was 37, total T3 was 90, and TRH < 5, radom sodium urine was 269, random creatinine was 256, random urine creat 258. She has sx of hypothyroid, tired all the time, recent weight gain of 15lbs. She is hungry all the time. Some depression at times, and chronic bradycardia. Do you think this is hypothyroid or is something else going on? I have not heard back from the cardiologist, went back to see PCP and she said labs were fine. I am an RN and I know that some of her labs are off. Any ideas or direction? My daughter is terrified she thinks she is dying, I don't know where else to turn. Thanks