How do I know if I have Iodine overdose?

This is connected to my last question, "Is too much seaweed bad for you?". That question has been answered, and i just discovered "Iodine overdose" from that question. And i'm wondering, how do I know whether I have Iodine overdose or not? How much seaweed would I have to eat to get Iodine overdose? (grams) If I have Iodine overdose, how can I stop it?