My daughter was in er after a seizure. her potassium was 2.8 & her heart rate was around 155.she's 14.we're waiting on eeg & mri. what causes this?

Upsetting: I empathize with how upsetting this but you must be patient and wait for the tests to be done and interpreted. There is a long list of causes for seizures, some serious, some not so much. The HR of 155 is likely the heart being an "innocent bystander" - when you have a seizure, you're stressed & your heart responds to that by speeding up. Unclear why her potassium is low but it's easily corrected.

Hard to say: The findings you list are not specific to a cause.The best people to answer your questions are those that have access to the full history, exam and all the test results. It is hard to wait & you usually go to a dark place expecting the worst.However, most cases will be a fixable problem.