Chapter Summary

Multinodular goiter is an enlarged thyroid gland with multiple colloid nodules that is frequently asymptomatic and euthyroid.

General features of hyperthyroidism include tachycardia, nervousness, diaphoresis, heat intolerance, weakness, tremors, diarrhea, and weight loss. Free T4 is elevated and TSH is decreased in primary hyperthyroidism and increased in secondary and tertiary hyperthyroidism.

Graves disease is an autoimmune disease characterized by production of IgG autoantibodies to the TSH receptor. Clinical features include hyperthyroidism, goiter, exophthalmos, and pretibial myxedema. Hyperthyroidism can also be caused by toxic multinodular goiter, toxic adenoma, and transiently during Hashimoto disease and subacute thyroiditis.

General features of hypothyroidism include fatigue, lethargy, sensitivity to cold temperatures, decreased cardiac output, myxedema, and constipation. Free T4 is decreased and TSH is elevated in primary hypothyroidism and decreased in secondary and tertiary hypothyroidism.

Congenital hypothyroidism develops secondary to iodine deficiency during intrauterine and neonatal life and causes mental retardation, musculoskeletal problems, and goiter. Endemic goiter is uncommon in the United States and is due to dietary deficiency of iodine.

Hashimoto thyroiditis is a chronic autoimmune disease characterized by immune destruction of the thyroid gland and hypothyroidism.

Subacute thyroiditis is a cause of transient hyperthyroidism following a viral illness.

Riedel thyroiditis is a rare disease of unknown etiology characterized by destruction of the thyroid gland by dense fibrosis of surrounding structures.

Thyroid adenomas are usually painless, solitary nodules.

Thyroid carcinomas occur in a number of histologic types, including papillary (most common with excellent prognosis), follicular (tends to spread hematogenously), medullary (secretes calcitonin, makes amyloid, and may be associated with MEN II or III), and anaplastic (rapidly fatal).

Primary hyperparathyroidism is most often due to parathyroid adenoma or parathyroid hyperplasia, and can be characterized by elevated serum calcium and PTH, kidney stones, osteoporosis and osteitis fibrosa cystica, metastatic calcifications, and neurologic changes. Many cases are asymptomatic Secondary hyperparathyroidism can be seen in any disease that results in hypocalcemia leading to increased secretion of PTH by the parathyroid glands, including chronic renal failure, vitamin D deficiency, and malabsorption,

Hypoparathyroidism is characterized by hypocalcemia, tetany, psychiatric disturbances, and cardiac conduction defects. It can be the result of surgical removal of the glands during thyroidectomy, DiGeorge syndrome, or it can be idiopathic.

Pituitary adenomas an produce prolactin (causing galactorrhea, amenorrhea, and infertility), growth hormone (causing gigantism and acromegaly), or other pituitary hormones. Sheehan syndrome is ischemic necrosis of the pituitary secondary to hypotension from postpartum hemorrhage resulting in panhypopituitarism. Diabetes insipidus is ADH deficiency resulting in hypotonic polyuria, hypernatremia, and dehydration. SIADH is excessive production of ADH, resulting in oliguria, water retention, hyponatremia, and cerebral edema.

Chapter Summary (continued)

Cushing syndrome is characterized by increased levels of glucocorticoids, whose origin may be iatrogenic, pituitary corticotroph adenoma, adrenocortical adenoma, or paraneoplastic syndrome.

Primary hyperaldosteronism occurs when an adrenocortical adenoma produces aldosterone, leading to hypertension, hypokalemia, elevated aldosterone, and decreased renin.

Adrenogenital syndromes are adrenal disorders characterized by excess production of androgens and virilization and can be due to either an adrenocortical adenoma/carcinoma or congenital adrenal hyperplasia.

Waterhouse-Friderichsen syndrome is acute adrenal insufficiency with shock and DIC seen in the setting of bilateral hemorrhagic infarction of the adrenal glands, usually in a child with a Neisseria infection.

Addison disease is chronic adrenocortical insufficiency and is due to destruction of the adrenal cortex, leading to a deficiency of glucocorticoids, mineralocorticoids, and androgens.

Pheochromocytoma is an uncommon tumor of the adrenal medulla that produces catecholamines and may present with severe headache, tachycardia, diaphoresis, and hypertensive episodes.

MEN I features tumors of the pituitary gland, parathyroids, and pancreas. MEN II features medullary carcinoma of the thyroid, pheochromocytoma, and parathyroid lesions. MEN III features medullary carcinoma of the thyroid, pheochromocytoma, and mucocutaneous neuromas.

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