Graves’ disease is the most common cause of hyperthyroidism, or overactive thyroid. In Graves’, the body’s hyperactive immune system produces an antibody that attaches to the TSH receptors on the thyroid gland. Because TSH isn’t actually triggering the release of T3 and T4, the negative feedback system the body has in place doesn’t work and the thyroid continually makes and releases thyroid hormones. Since the antibodies consistently trigger the thyroid cells to produce more T3 and T4, the body responds by increasing the thyroid’s size, causing a classic thyroid symptom called goiter. 

The other primary external symptom of Graves’ is called exophthalmos, or protrusion of the eyes. Exophthalmos has two causes. The first is due to a prolonged ‘fight or flight’ response – the widening of the eyes by a retraction of the upper lids. The second is due to that overactive immune system: the fat and muscles around the eyes become swollen due to an increase in the number of lymphocytes present and other symptoms of inflammation, pushing the eyes forward. 

Internally, excess thyroid hormones are also stressing the sympathetic nervous system, constantly preparing us for a threat that’s not really there. Resting metabolic rate increases, causing weight loss. Resting heart rate jumps irregularly (arrhythmia) or increases to over 100 beats per minute (tachycardia). Heat intolerance and heavy perspiration are also symptoms. 

Diagnosis of Graves’ through blood tests relies largely on high-circulating levels of T3 and T4 and low TSH levels, as well as antibodies for TSH receptors. Occasionally, an iodine uptake test is used for confirmation. In this test, the patient consumes a low dose of radioactive iodine. Since thyroid cells actively take up iodine, the degree and location of overactive cells present in radiography as darkened areas of the thyroid. 

Pharmaceutical treatment for Graves’ consists of symptom relief through beta blockers, which dull sympathetic nervous system activity, and antithyroid medications that prevent the thyroid from making hormones, such as methimazole. In more severe cases, surgical removal of or destruction of the hyperactive cells through radioactive iodine is a treatment option.