HYPOTHYROIDISM

Hypothyroidism is a condition where the thyroid gland does not produce the required amount of thyroid hormones. Before going further into understanding hypothyroidism, let’s first know about the normal functions of the thyroid gland.
The thyroid gland is an endocrine gland (Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct), a butterfly-shaped gland that is situated in front of the neck just below Adam’s apple (larynx).
The thyroid gland releases hormones that control the metabolism, the way the body uses energy, and also regulates other main functions like heart rate, breathing, body temperature, menstrual cycle, cholesterol levels, body weight, muscle strength, and many more.
The thyroid gland uses iodine to produce two main hormones called

• Triiodothyronine (T3)
• Thyroxin (T4)

The hypothalamus and pituitary gland maintain the T3 and T4 balance. When there is a low level of T3 and T4 hormones, the hypothalamus, which is in the brain, produces TSH Releasing Hormone (TRH), which stimulates the pituitary gland to release Thyroid Stimulating Hormone (TSH). This TSH hormone, in turn, stimulates the thyroid gland to produce thyroid hormones.When T3 and T4 levels are low in the blood, the pituitary gland releases more TSH to tell the thyroid gland to produce more thyroid hormones. If T3 and T4 levels are high, the pituitary gland releases less TSH to the thyroid gland to slow the production of these hormones.
So now we know how the thyroid hormones are produced and what are the main functions of these hormones. Let’s know what happens when these hormones are not balanced, i.e., when hormones are not produced as required.
As already said, when thyroid hormones are less, TSH is released to stimulate the thyroid gland to produce more thyroid hormones. If for some reason, the thyroid hormone is not produced by thyroid glands as required, negative feedback reaches the brain which leads to more secretion of TSH. This causes a vicious cycle and leads to higher than normal levels of TSH in blood and lower than normal levels of T3 and T4. This condition is called ‘hypothyroidism’, also called ‘underactive thyroid’.

WHAT IS THE CAUSE FOR THYROID TO NOT FUNCTION PROPERLY?

1. The common causes of hypothyroidism are

• Autoimmune response – Hashimoto’s disease
• Surgical removal of the thyroid gland
• Radiation therapy
• Certain Medicines

2. Other causes are

• Pregnancy
• Congenital
• Iodine deficiency
• Pituitary disorder – a benign tumour of the pituitary gland

3. Other risk factors are

• If you are a woman of age 60years or above
• Has a family history of thyroid disorder
• Have an autoimmune disease like rheumatoid arthritis etc.
• Treated with radioactive iodine

SIGNS AND SYMPTOMS OF AN UNDERACTIVE THYROID OR HYPOTHYROIDISM

The symptoms usually vary from person to person and severity of the condition. Most common and early symptoms are weight gain and fatigue. The symptoms are sometimes difficult to identify. One may not realize these symptoms are related to thyroid until more symptoms appear. But as your metabolism continues to slow, you may develop more obvious signs and symptoms.
The symptoms are as follows

• Fatigue
• Increased sensitivity to cold
• Constipation
• Dry skin
• Weight gain
• Puffy face
• Hoarseness
• Muscle weakness
• Elevated blood cholesterol level
• Muscle aches, tenderness and stiffness
• Pain, stiffness or swelling in your joints
• Heavier than normal or irregular menstrual periods
• Thinning hair
• Slowed heart rate
• Depression
• Impaired memory

DIAGNOSIS

The diagnosis is done through clinical signs and symptoms, like fluctuation in weight, dry skin etc., and confirmation by blood tests for TSH, T3, T4 levels.

MEDICATIONS

The drug used in hypothyroidism is levothyroxine, which is a synthetic version of T4. It does the functions of the thyroid hormone.
Usually, this medicine once started, will have to be continued for the entire lifetime of an individual. The dosage of the drug is to be monitored and adjusted according to the need, which is determined by regular blood tests of thyroid levels.

SECONDARY  HYPOTHYROIDISM

Secondary hypothyroidism occurs when the hypothalamus produces insufficient thyrotropin-releasing hormone (TRH) or the pituitary produces insufficient TSH. Sometimes, deficient TSH secretion due to deficient TRH secretion is termed tertiary hypothyroidism.