**3. Classification of goiter**

Goiter can be classified based on anatomically, etiologically, pathophysiologic ally and functionally (**Table 1** and **Figure 1**).

#### **3.1 Dyshormonogenesis**

Autosomal recessive disorders (exception DUOX 2 mutation). Enzymatic defect in one of the steps of thyroid hormone synthesis. The most common cause being the deficiency of thyroid peroxidase enzyme. Prevalence is more among females.


**5**

*Goiter: Overview of Aetiopathogenesis and Therapy DOI: http://dx.doi.org/10.5772/intechopen.90028*

monogenetic goiter is associated with deafness.

*Classification of goiter on the basis of pathophysiology.*

**3.2 Dietary factors**

**Figure 1.**

*3.2.1 Iodine deficiency*

*3.2.2 Dietary goitrogens*

**3.3 Drugs causing goiter**

**3.4 Hashimotos thyroiditis**

Phenobarbitone.

ing women.

Most of the cases present clinically before third decade with as earliest as in neonatal period with goiter and hypothyroidism. In Pendred syndrome dyshor-

Twenty-nine percent of world population lives in area where soil is deficient in iodine, e.g., the Himalayan region in India. The most common cause of goiter worldwide is iodine deficiency. More than 30% of population having median urine iodine less than 20 mcg/l developed goiter [9]. Daily requirement of iodine is 100–150 mcg/day, but the requirement increases in pregnant and lactat-

Soy and Millet contains flavonoids which impair thyroid peroxidase activity. Cyanogenic glucosides in Cassava, Lima beans compete for iodine uptake in thyroid follicles. Similarly cruciferous vegetables like cabbage cauliflower, broccoli contains

Drugs like Lithium, Amiodarone apart from Antithyroid drugs are known to cause goiter. Rare causes include Interferon Alfa, Rifampicin, Phenytoin, and

The condition is named after Japanese physician Hakaru Hashimoto. This autoimmune thyroid disorder is characterized by diffuse lymphocytic infiltration of thyroid gland along with follicular destruction. Serologically the patients have high titer of anti-thyroglobulin and anti TPO antibodies. Hashimoto's thyroiditis is the next most common cause of hypothyroidism after iodine deficiency. But subset of patient may remain clinically and biochemically euthyroid for rest of the life. The

glucosinolates which also competes with thyroidal iodine uptake.

condition has female to male prevalence ratio of 7:1.

#### **Table 1.**

*Anatomical, functional and morphological classification of goiter.*

*Goiter: Overview of Aetiopathogenesis and Therapy DOI: http://dx.doi.org/10.5772/intechopen.90028*

**Figure 1.**

*Goiter - Causes and Treatment*

7–10 ml and weighing of 9–21 g.

lymph node.

**3. Classification of goiter**

**3.1 Dyshormonogenesis**

Cervical goiter Retrosternal goiter Intrathoracic goiter **Functional classification**

Toxic goiter Non-toxic goiter • Euthyroidism • Hypothyroidism

Diffuse goiter Nodular goiter • Solitary nodular goiter • Multinodular goiter

**Anatomical classification of goiter**

**Morphological classification**

*Anatomical, functional and morphological classification of goiter.*

ally and functionally (**Table 1** and **Figure 1**).

**2. Anatomy and embryology of thyroid gland**

lie adjacent to follicles. C cell produce calcitonin.

Thyroid gland is located anteriorly in lower neck and extending between C5 to T1 vertebrae. A normal adult thyroid gland is approximately 40–60 mm longitudinal and 13–18 mm AP diameter in size [8]. Mean ultrasound volume is around

Microscopically the gland is divided into lobes and lobules. Lobules are further subdivided into follicles. These follicles are made up of principal (follicular) cells which are a type of epithelial cell. These cells produce colloid (iodo-thyroglobulin). Other types of epithelial cells seen in gland are parafollicular cells (c cell) which

Thyroid gland development starts by third to fourth week of gestation and originates from primitive pharynx and the neural crest cells. The development begins as a diverticulum at the dorsum of tongue. This diverticulum forms hypoglossal duct which passes from foramen caecum to infrahyoid region. The supra hyoid part of thyroglossal duct degenerates whereas the infra hyoid part develops into thyroid gland. The gland is supplied by superior thyroid artery, inferior thyroid artery and thyroidea ima. Venous drainage is provided by superior, middle and inferior thyroid vein. The lymphatic drainage courses to prelaryngeal, pretracheal and paratracheal

Goiter can be classified based on anatomically, etiologically, pathophysiologic

Autosomal recessive disorders (exception DUOX 2 mutation). Enzymatic defect in one of the steps of thyroid hormone synthesis. The most common cause being the

deficiency of thyroid peroxidase enzyme. Prevalence is more among females.

**4**

**Table 1.**

*Classification of goiter on the basis of pathophysiology.*

Most of the cases present clinically before third decade with as earliest as in neonatal period with goiter and hypothyroidism. In Pendred syndrome dyshormonogenetic goiter is associated with deafness.
