23-year old male, possibly with thyroid issue (iodine deficiency?), very slow heart rate (resting 46-48 bpm), had echocardiogram (structure fine, normal), stress test tolerated exercise very well, holter monitor showed possible erratic electric impulses on occasion. This is from cardiologist, but cardiologist wants me to see electrical rhythm doctor (I m fine with that). However, he wants me to start taking Toprol right now. Asked about side effects of toprol, no answer from dr. Looked them up and it said it can cause slower heart rate, difficulty breathing, etc. ????? My slow heart rate is one of the reasons I was at cardiologist today. He said it could be from a chemical imbalance, etc. so why wouldn t he want to know what s causing it before prescribing something? Besides, I m pretty sure I m iodine deficient, just started taking an oral iodine supplement recently. So confused and tired of seeing too many doctors with NO answers. . . They haven t done ultrasound of my neck/thyroid yet as doctor wants one ordered.