Goiter
Goiter: Excerpt from Handbook of Diseases
Nontoxic or simple goiter — thyroid gland enlargement not caused by inflammation or a neoplasm — is commonly classified as endemic or sporadic.
Endemic goiter usually results from inadequate dietary intake of iodine associated with such factors as iodine-depleted soil and malnutrition. Sporadic goiter follows ingestion of certain drugs or foods.
Endemic goiter affects females more than males, especially during adolescence and pregnancy, when the demand on the body for thyroid hormone increases. Sporadic goiter affects no particular population segment. With appropriate treatment, the prognosis is good for either type.
Causes
Simple goiter occurs when the thyroid gland can’t produce and secrete enough thyroid hormone to meet metabolic requirements. As a result, the thyroid gland enlarges to compensate for inadequate hormone synthesis. Such compensation usually overcomes mild to moderate hormonal impairment.
Because thyroid-stimulating hormone (TSH) levels are generally within normal limits in patients with simple goiter, the disease probably results from impaired intrathyroidal hormone synthesis or depletion of glandular iodine, which increases the thyroid gland’s sensitivity to TSH. Thyroid growth-stimulating immunoglobulins can also cause gland enlargement. However, increased levels of TSH may be transient and therefore missed.
Endemic goiter
Endemic goiter usually results from inadequate dietary intake of iodine, which leads to inadequate production and secretion of thyroid hormone. The use of iodized salt prevents this deficiency.
Sporadic goiter
Sporadic goiter commonly results from the ingestion of large amounts of goitrogenic foods or the use of goitrogenic drugs.
Goitrogenic foods contain agents that decrease thyroxine (T4) production. Such foods include rutabagas, cabbage, soybeans, peanuts, peaches, peas, strawberries, spinach, and radishes.
Goitrogenic drugs include propylthiouracil, methimazole, iodides, and lithium. In a pregnant woman, such substances may cross the placenta and affect the fetus.
Both types
Inherited defects may be responsible for insufficient T4 synthesis or impaired iodine metabolism. Because families tend to congregate in a single geographic area, this familial factor may contribute to the incidence of both endemic and sporadic goiter.
Signs and symptoms
Thyroid enlargement may range from a mildly enlarged gland to a massive, multinodular goiter. Because simple goiter doesn’t alter the patient’s metabolic state, clinical features arise solely from enlargement of the thyroid gland.
The patient may complain of respiratory distress and dysphagia from compression of the trachea and esophagus and from swelling and distention of the neck.
In addition, large goiters may obstruct venous return, produce venous engorgement and, in rare cases, induce development of collateral venous circulation in the chest. Such obstruction may cause dizziness or syncope when the patient raises his arms above his head.
Diagnosis
An accurate diagnosis of simple goiter requires a thorough patient history and physical examination to rule out disorders with similar clinical effects, such as Graves’disease, Hashimoto’s thyroiditis, and thyroid carcinoma. A detailed patient history also may reveal goitrogenic medications or foods or endemic influence.
The results of diagnostic laboratory tests include the following:
❑ TSH — high or normal
❑ serum T4 concentrations — low normal or normal
❑ iodine 131 uptake — normal or increased (50% of the dose at 24 hours).
Treatment
The goal of treatment is to reduce thyroid hyperplasia. The following measures are used:
❑ Exogenous thyroid hormone replacement with levothyroxine is the treatment of choice; it decreases TSH secretion and allows the gland to rest. (See Patient instructions in goiter.)
❑ Small doses of iodine (Lugol’s or potassium iodide solution) commonly relieve goiter caused by iodine deficiency. Sporadic goiter requires avoidance of known goitrogenic drugs and foods.
❑ A large goiter that’s unresponsive to treatment may require subtotal thyroidectomy.
Special considerations
❑ Measure the patient’s neck circumference to check for progressive thyroid gland enlargement. Also check for the development of hard nodules in the gland, which may indicate carcinoma.
❑ Monitor the patient taking goitrogenic drugs for signs of sporadic goiter.
❑ Teach the patient about iodized salt, medications, and the symptoms of thyrotoxicosis.
Pictures
Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
More About Graves Disease
More Medical Textbooks Online about Graves Disease
Review other book chapters online related to Graves Disease:
Medical Books Excerpts
- Goiter
- "The 5-Minute Pediatric Consult" (2008)
- [ read ]
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
|
|
More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
|
|
» Next page: Exophthalmos (Signs & Symptoms: A 2-in-1 Reference for Nurses)
Rate This Website
What do you think about the features of this website?
Take our user survey and have your say:
Website User Survey
Medical Tools & Articles:
Next articles:
Tools & Services:
Medical Articles:
Forums & Message Boards
- Ask or answer a question at the Boards:
