A thyroid disease refers to conditions that affect the thyroid gland, which is a butterfly-shaped gland located at the base of the neck. This gland regulates many metabolic processes for the body, and thyroid diseases like hypothyroidism, hyperthyroidism, goiter, thyroid nodules, and thyroid cancer can affect its functioning or structure. This makes understanding the causes, symptoms, and types of thyroid disease important to manage and treat it effectively.

Thyroid disease: Causes, symptoms, and types

Hyperthyroidism
This refers to the overproduction of the thyroid hormone, but this condition can be due to any of the following factors:

• Toxic adenomas : There is a development of nodules in the gland that start secreting thyroid hormones and upset the chemical balance in the body.
• Grave’s disease : This occurs because of the overproduction of the thyroid hormone.
• Subacute thyroiditis : This happens when the thyroid gland experiences inflammation and leaks excess hormones, causing temporary hyperthyroidism that can last from a few weeks to months.
• The pituitary gland malfunctions or the thyroid gland has cancerous growths : This is a rare but possible cause of hyperthyroidism.

Hypothyroidism
When the gland produces insufficient thyroid hormone, it leads to hypothyroidism. Some of the symptoms associated with this are fatigue, dry skin, muscle weakness and aches, sensitivity to cold, fluid retention, depression, and excessive menstrual bleeding or irregular cycles. When hypothyroidism is not treated for long, it can lead to myxedema coma, which is a rare but fatal condition. The causes of hypothyroidism may be attributed to the following factors:

• Hashimoto’s thyroiditis : This is an autoimmune disease attacking the thyroid tissues, which eventually die and stop releasing hormones.
• Removal of the thyroid gland : When the thyroid gland is removed surgically or destroyed chemically, it may lead to hypothyroidism.
• Exposure to excess iodine : This can happen through cold or sinus medicines, and contrast dyes given before X-rays may also expose you to iodine.
• Lithium : This has been thought to be a cause of this condition.

Goiter
This refers to thyroid gland enlargement, no matter what causes it. This is not really a disease, but it can be related to hyperthyroidism, hypothyroidism, and normal thyroid function.

Thyroid nodules
These refer to abnormal masses and lumps inside the gland that can be because of benign tumors and cysts. Large nodules may trigger symptoms that are linked to compression of the surrounding structures.

Thyroid cancer
This is a much more common medical condition among adult women than in men, and most people are below the age of 55 years when diagnosed with this condition. Thyroid cancers can be of different types depending on the cell type in the thyroid affected by cancer. However, the good news is that most cases have a very good prognosis and the survival rates are high, particularly when diagnosed early.

Postpartum thyroiditis
This refers to thyroid inflammation post-delivery, and the symptoms usually manifest within 1 to 4 months of delivery. The common symptoms are tiredness, mood swings, constipation, dry skin, and depression.