of the eyelids and face, thick dry skin, cold intolerance, slow pulse, constipation,
weight gain, and abnormal menses.
In children, hypothyroidism can have a congenital (cretinism) or prepubertal
(juvenile hypothyroidism) onset.
Hypothyroidism is treated by administering levothyroxine sodium
(Levothroid, Synthroid), which increases levels of T3 and T4. Levothyroxine
sodium (Levothroid, Synthroid) is also used to treat simple goiter and chronic
lymphocytic (Hashimoto’s) thyroiditis.
Lyothyronine (Cytomel) is a synthetic T3 that is used for short-term treatment
of hypothyroidism. It isn’t used for maintenance therapy because lyothyronine
has a short half-life and duration.
Liotric (Euthroid, Thyrolar) is a mixture of levothyroxine sodium and liothy-
ronine sodium with no significant advantage over levothyroxine sodium.
Thyroid and thyroglubin (Proloid) are seldom used.
A list of drugs utilized in the treatment of hypothyroidism is provided in the
Appendix. Detailed tables show doses, recommendations, expectations, side
effects, contraindications, and more; available on the book’s Web site (see URL
in Appendix).Hyperthyroidism
Hyperthyroidism is an increase in circulating T4 and T3 levels resulting from
an overactive thyroid gland or excessive output of thyroid hormones.
Hyperthyroidism may be mild with few symptoms or severe leading to vascular
collapse and death.
Graves’ disease or thyrotoxicosis is the most common type of hyperthy-
roidism and is caused by a hyperfunctioning thyroid gland. Graves’ disease is
characterized by a rapid pulse (tachycardia), palpitations, excessive perspiration,
heat intolerance, nervousness, irritability, exopthalmos (bulging eyes), and
weight loss. Treatment involves surgical removal of a portion of the thyroid
gland (subtotal thyroidectomy), radioactive iodine therapy, or antithyroid drugs
that inhibit either the synthesis or the release of thyroid hormones.
Antithyroid drugs reduce the excessive secretion of T4 and T3 by inhibiting
thyroid secretion. Thiourea derivatives (thioamides) are the drugs of choice used
to decrease thyroid production.
Propylthiouracid (PTU) and methylthiouracil (Tapazole) are effective
thioamide antithyroid drugs used for treating thyrotoxic crisis and in preparation
for subtotal thyroidectomy. Methimazole does not inhibit peripheral conversion
of T4 to T3 as does PTU, but it is 10 times more potent and has a longer half-
life than PTU. Prolonged use of thioamides may cause a goiter because of the(^390) CHAPTER 21 Endocrine Medications