This lecture was conducted during the Nephrology Unit Grand Ground by Medical Student rotated under Nephrology Division under the supervision and administration of Prof. Jamal Al Wakeel, Head of Nephrology Unit, Department of Medicine and Dr. Abdulkareem Al Suwaida. Nephrology Division is not responsible for the content of the presentation for it is intended for learning and /or education purpose only.

Outlines: Thyroid gland & mechanism Goiter: Definition Classification Causes Symptoms Risk factor Tests and diagnosis Treatments Lifestyle

The thyroid is a small, butterfly- shaped gland inside the neck, just below the Adam’s apple. The thyroid gland produces hormones which control the body’s metabolism and regulate the rate at which the body carries out its functions

Definition: A goiter is an abnormal enlargement of the thyroid gland and can occur for a number of different reasons..

Mortality/Morbidity: Most goiters are benign, causing only cosmetic disfigurement. Morbidity or mortality may result from compression of surrounding structures, thyroid cancer, hyperthyroidism, or hypothyroidism.

Sex and age: The female-to-male ratio is 4:1 In the Wickham study, 26% of women had a goiter, compared to 7% of men. Thyroid nodules are less frequent in men than in women, but when found, they are more likely to be malignant.

Classification: Toxic goiter: A goiter that is associated with hyperthyroidism is described as a toxic goiter. Examples of toxic goiters include diffuse toxic goiter (Graves disease), toxic multinodular goiter, and toxic adenoma

Nontoxic goiter: A goiter without hyperthyroidism orhypothyroidism is described as a nontoxic goiter. It may be diffuse or multinodular Examples of nontoxic goiters including goiter identified in early Graves disease, congenital goiter, and physiologic goiter that occurs during puberty

Other type of classification: I - palpation struma - in normal posture of head it cannot be seen. Only found when palpating. II - struma is palpative and can be easily seen. III - struma is very big and is retrosternal. Pressure and compression marks.

Causes: Worldwide, the most common cause for goiter is iodine deficiency. In countries that use iodized salt, Hashimoto's thyroiditis becomes the most common cause.

- Excess iodine or lithium ingestion, which decrease release of thyroid hormone -Goitrogens(cassava, lima beans, maize, bamboo shoots, and sweet potatoes)

-Inborn errors of metabolism causing defects in biosynthesis of thyroid hormones - Exposure to radiation -Thyroid hormone resistance

Side-effects of pharmacological therapy such as: Amiodarone : inhibits peripheral conversion of thyroxine to triiodothyronine; also interferes with thyroid hormone action. Phenobarbitone, phenytoin, carbamazepine, Rifampcin: induce metabolic degradation of T3 and T4.

Graves' disease Thyroiditis Thyroid cancer

Graves' disease one’s immune system produces a protein, called thyroid stimulating immunoglobulin (TSI). As with TSH, TSI stimulates the thyroid gland to enlarge producing a goiter. However, TSI also stimulates the thyroid to make too much thyroid hormone (causes hyperthyroidism).

It can also affect the eyes, causing bulging eyes (exophthalmos). It affects other systems of the body, including the skin, heart, circulation and nervous system.

Thyroiditis: it is the inflammation of the thyroid gland.This disease is often considered a malfunction of the immune system. Antibodies that attack the thyroid are what causes most types of thyroiditis. It can also be caused by an infection, like a virus or bacteria.

Hashimoto's thyroiditis: This is a autoimmune condition in which there is destruction of the thyroid gland by one’s own immune system. As the gland becomes more damaged, it is less able to make adequate supplies of thyroid hormone.

The pituitary gland senses a low thyroid hormone level and secretes more TSH to stimulate the thyroid. This stimulation causes the thyroid to grow, which may produce a goiter.

Thyroid neoplasm or thyroid cancer usually 4 kinds of malignant tumors of the thyroid gland: papillary, follicular, medullary or anaplastic

Symptoms: In general: -Swelling or disfigurement of the neck -Afeeling of tightness in the throat -Coughing -Difficulty breathing -Difficulty swallowing

Hyperthyroidism: Weight loss, heat intolerance, trembling hands, palpitations, insomnia, anxiety, increased bowel movement frequency.

Hypothyroidism: Weight gain, cold intolerance, constipation, very dry skin, depressed mood, muscle cramping.

Symptoms of Possible Cancer Spread: Bone pain in one spot without relief Weakness or numbness of an arm or leg that persists.

Examination of the goiter is best performed with the patient upright, sitting or standing. Inspection from the side may better outline the thyroid profile, as shown below. Asking the patient to take a sip of water facilitates inspection. The thyroid should move upon swallowing.

Palpation of the goiter is performed either facing the patient or from behind the patient, with the neck relaxed and not hyperextended. Each lobe is palpated for size, consistency, nodules, and tenderness. Cervical lymph nodes should be palpated.

Palpation of the goiter rules out a pseudogoiter, which is aprominent thyroid seen in individuals who are thin.

The pyramidal lobe often is enlarged in Graves disease. A firm rubbery thyroid gland suggests Hashimoto thyroiditis. Multiple nodules may suggest a multinodular goiter or Hashimoto thyroiditis.

A solitary hard nodule suggests malignancy, whereas a solitary firm nodule may be a thyroid cyst. Diffuse thyroid tenderness suggests subacute thyroiditis, and local thyroid tenderness suggests intranodal hemorrhage or necrosis. Cervical lymph nodes are palpated for signs of metastatic thyroid cancer

Auscultation of a soft bruit over the inferior thyroidal artery may be appreciated in a toxic goiter. Palpation of a toxic goiter may reveal a thril.

Risk factor: A lack of dietary iodine. sex. Because women are more prone to thyroid disorders than men age. Being age 50 or older Medical history. A personal or family history of autoimmune disease

Pregnancy and menopause. Certain medications. immunosuppressants, the heart drug amiodarone and the psychiatric drug lithium Radiation exposure.

Tests and diagnosis Hormone test: If the thyroid is overactive,the level of thyroid hormone in the blood will be high and the level of thyroid stimulating hormone (TSH) will be low If the thyroid is underactive the level of thyroid hormone will be low while the level of TSH will be high.

Antibody test: auto-immune antibodies. Ultrasonography: To show the size of the thyroid gland and the presence of any nodules.

Fine needle aspiration biopsy

Thyroid scan: This scan will help evaluate the structure and function of the thyroid and involves the administration of radioactive substance.

Treatment: Small benign euthyroid goiters do not require treatment.just observe. iodine supplementation by mouth

If hypothyroidism thyroid hormone replacement with levothyroxine(Levothroid,Synthroid)

aspirin or a corticosteroid medication to treat the inflammation.

Hyperthyroidism: anti-thyroid drugs such as methimazole (Tapazole) or propylthiouracil (PTU). For advanced hyperthyroidism, radioactive iodine treatment (RAI).

Surgery Large goiters with compression Malignancy When conventional drug therapy for overactive thyroid is not successful

Lifestyle: Get enough iodine(Sea vegetables, Yogurt, cow's milk, eggs, and strawberries ) The recommended minimum daily intake of iodide is 150 mcg for adults, 220 mcg for pregnant women, and 290 mcg for lactating women. avoid excessive consumption.

Avoid Goitrogens (Foods that contain cyanoglucosides include cassava, lima beans, maize, bamboo shoots, and sweet potatoes.)

Done by Ibtisam Al-Qahtani