A low thyroid function has specific causes, yet the symptoms of this condition are numerous and can be mistaken for symptoms of other disorders, including psychological syndromes. Also, as an individual you might experience and describe your signs of a low thyroid in a unique way that can confuse the issue.
To add to this, a blood test may show that your thyroid hormones are low, but still considered in a normal range, not requiring drug therapy. If this is the case, while frustrating for you, you are lucky, because remedying a couple of simple nutritional deficiencies may return you to a true 'normal'. Review the following symptoms typically associated with a hypothyroid condition:
difficulty losing weight
tired all the time
moodiness
hair loss
loose skin
depression
aching muscles
feeling cold
Chronic Fatigue Syndrome
lack of libido
sore joints
memory loss

difficulty concentrating
It is easy to see why this 'low normal' thyroid function can be difficult to figure out. If you are over forty, you may be told that your natural aging process has started. If your dominant symptom is depression, for example, you may be prescribed psychiatric drugs. These will for certain not help your thyroid hormones get up to par. And so on and so on with each symptom - a dominant symptom can be assigned to the wrong diagnosis.
Nutritional factors can be explored here. It is common knowledge that an iodine deficiency can be responsible for a sluggish thyroid gland. Yet, iodine is only part of the nutrition required to manufacture thyroid hormones. If you are deficient in other minerals like selenium, copper, and zinc, and the amino acid L-Tyrosine, just taking some iodine won't help to completely remedy the situation.