Various factors have been associated with the cause of goiter such as hereditary, hormonal, dietary, pharmacological, physiological, environmental and pathological factors. The most common causes being, iodine deficiency, Grave’s disease and hashimoto’s disease. Goiter may be caused by a mutation in the genes such as the thyroglobulin (Tg) gene, thyroid-stimulating hormone receptor (TSHR) gene and the sodium-iodide symporter (NIS) gene.

Factors associated with goiter can be classified as follows:

Hereditary factors

• Inherited defect(Familial goiter) of thyroid hormone synthesis such as:
  • Enzymatic defect deficiency
  • Dyshormonogenesis

Hormonal factors

Thyroid hormone dysfunction:

• Hyperthyroidism (overproduction of thyroid hormones)
• Hypothyroidism (underproduction of thyroid hormones)

Dietary factors

• Dietary iodine deficiency
• Goitrogens (play a major role in endemic goitre)

Pharmacological factors

• Use of goitrogenic drugs like para-aminosalicylic acid (PAS), thiocyanate and antithyroid drugs [e.g. thiouracil, carbimazole] results in hypothyroidism

Physiological factors

• Increased metabolic demand of thyroid hormones e.g. during pregnancy or puberty results in physiological goiter.

Environmental factors

• Exposure to radiations leading to:
  • Thyroid cancer
  • Hypothyroidism

Pathological factors

Intrinsic thyroid gland diseases:

• Inflammatory goitres
• Neoplastic goitres
  • Benign adenoma (follicular adenoma)
  • Malignant
    • Primary: Well differentiated, poorly differentiated, arising from parafollicular cells
    • Secondary

Goiter may be caused by:

• Iodine deficiency
• Grave’s disease
• Hashimoto’s disease

Less common causes of Goiter include:

• Pregnancy
• Radiation exposure
• Thyroid cancer
• Multinodular goiter
• Solitary thyroid nodules

• Goiter may be caused by a mutation in the following genes which vary from one family to the other: ^[1]

• Thyroglobulin (Tg) gene
• Thyroid-stimulating hormone receptor (TSHR) gene
• Sodium-iodide symporter (NIS) gene

• Multinodular goiter marker 1 (MNG1) on chromosome 14 ^[1]