This is what happened to me:

My doctor tested me. My level was 1.57. He said, oh okay, you're fine. No worries.

2 years and 70 pounds later I go in to my doctor. "Hey, I gained a lot of weight and I don't understand why."

He says, "Oh, let's test you for thyroid problems."

Me: "But you said I was fine..."

He says, "Oh, I did? Well let's check to be safe."

It was 3.84. While it still falls within the high end of the normal range on his lab sheet (normal on his said 3.90), it SHOULD NOT have more than doubled. It should have stayed the same.

So he's like, "Oh, oops. Sorry about that. I guess we should have checked you a second time to compare."

Even if your levels are low, DO NOT believe when they say that you're fine. If you believe the problem has recently started, it could be why it's still low. Have them check it. Have them check it every month to every 3 months. Just to compare. If it goes up, then you have a problem.

Please talk to your doctor about this. I would hate to see someone else fall into the same trap as I did.