Mulan

hyperthyroidismHyperthyroidism / Thyrotoxicosis

Thyrotoxicosis is an excess of thyroid hormone.

Hyperthyroidism is an excess of thyroid hormone caused by overactive thyroid tissue.

Hyperthyroidism is almost always (>99%) a primary thyroid problem.

Signs of hyperthyroidism include:

--heat intolerance, insomnia --anxiety, irritability, tremor, hyper-reflexia

--increased metabolism, weight loss --hyperdefecation

--palpitations, tachyarrythmias --hypercalcemia, hypercalciuria

--warm moist skin, sweating --gynecomastia

Graves’ Disease

**The most common cause of hyperthyroidism is Graves’ Disease.

Graves’ Disease is an autoimmune disease in which thyroid stimulating immuglobulins (TSIs) bind and activate the TSH receptor on thyrocytes.

Graves’ Disease occurs mostly in 15-35 yo females.

Some particular signs of Graves’ Disease include:

1. Graves’ ophthalmopathy (proptosis, extraocular muscle fibrosis, retroorbital fat/edema)

2. Pretibial myxedema (non-pitting edema)

3. Thyroid achropachy (clubbing of the digits)

All of these signs are caused directly by the TSIs, not the excess thyroid hormones. So these signs are seen in Graves’ Disease but not thyrotoxicosis. Also, removing the thyroid gland to correct the hormone imbalance will not correct Graves’ ophthalmopathy or myxedema.

Other causes of primary hyperthyroidism

1. Toxic Adenoma, a single large autonomously functioning hyperplastic thyroid nodule.

2. Toxic Multinodular Goiter, a growth of multiple autonomously functioning hyperplastic nodules.

3. Subacute thyroiditis, often preceded by a viral illness and causing exquisite thyroid gland pain that radiates to the jaw and ears. Radionuclide uptake is very low.

4. Lymphocytic (Autoimmune) thyroiditis, which may have a period of hyperthyroidism followed by hypothyroidism. This oftens occurs postpartum. Radionuclide uptake is very low.

Diagnosis of hyperthyroidism

**In primary hyperthyroidism (>99%), TSH...