Scenario 4: Hypothyroidism A patient  walked into your  clinic today with the following complaints: Weight gain (15 pounds), however has a decreased appetite with extreme fatigue,  cold intolerance, dry skin, hair loss, and falls asleep watching television. The patient also tearfulness with depression, and with an unknown cause and has noted she is more forgetful.  She does have blurry vision.

Hypothyroidism is a hypometabolic state that results from a deficiency in T4 and T3. The most common cause of hypothyroidism is an autoimmune disorder called Hashimoto disease, in which the thyroid is destroyed by antibodies or lymphocytes that attack the gland. Other causes are thyroiditis, congenital hypothyroidism, thyroidectomy, radiation to the thyroid, medications, iodine deficiency, and pituitary disease. Hypothyroidism is an underactive thyroid that does not produce enough hormones.

Patients with primary hypothyroidism have elevated TSH levels and decreased free hormone levels. Patients with elevated TSH levels (usually 4.5- 10.0 mIU/L) but normal free hormone levels or estimates are considered to have mild or subclinical hypothyroidism. The most common cause of hypothyroidism is autoimmune thyroiditis known as Hashimoto’s disease. Primary hypothyroidism is essentially the only disease that is characterized by sustained rises in TSH levels. As the TSH level increases early in the disease, conversion of T4 to T3 increases, maintaining T3 levels. In early hypothyroidism, TSH levels are elevated, T4 levels are normal to low, and T3 levels are normal.