Hypoerthyroid and Hypothyroid are more common especially in women. With today study many thyroid specialists are saying that if thyroid blood testing are normal means you are definitely defficient in iodine.
It is said that thyroid and iodine together are the most important role in the body and as the body have enough amount of iodine the thyroid works strong and you won't have a sluggish thyroid causing you feeling weak, fatigue or lack of energy. Sluggish thyroid definitely makes you weak.
When you are at your doctor office it is best to talk about iodine levels and be sure about this. They call it Iodine loading test the test is done through urine.