What is thyroid gland?
The thyroid gland is located inside the neck just below the voice box (larynx). It produces two thyroid hormones, triiodothyronine (T3) and tetraiodothyronine (T4), which regulate how the body uses and stores energy. This is called metabolism.

Thyroid is controlled by another gland called the pituitary, which is located inside your brain. It produces thyroid stimulating hormone (TSH), which stimulates the thyroid to produce T3 and T4.

What is hypothyroidism?

Hypothyroidism means you have too little thyroid hormone. Symptoms may include:

• Tiredness /sluggishness
• mental depression
• forgetfulness
• feeling cold
• weight gain (only 2-4 kg)
• dry skin and hair
• constipation
• menstrual irregularities

What causes hypothyroidism?

• Autoimmune disease. In some people’s bodies, the immune system that protects the body from invading infections can mistake thyroid gland cells and their enzymes for invaders and can attack them.
• Other causes are- surgical removal of the thyroid glandor radiation treatment for other thyroid illness, congenital hypothyroidism,medicines (amiodarone, lithium, interferon alpha, and interleukin-2), damage to the pituitary gland and rare disorders that infiltrate the thyroid (amyloidosis, sarcoidosis hemochromatosis).

Why care about hypothyroidism?

In adults, untreated hypothyroidism can lead to poor mental and physical performance. It can affect blood pressure and cholesterol levels and increases risk of heart disease in future.

Diagnosis of hypothyroidism is especially important during pregnancy to ensure delivery of a healthy baby. Thyroid hormone is important for baby’s brain development upto the age of 2 years. Routine testing of all babies at birth identifies those with hypothyroidism. If treated timely, mental retardation can be prevented in the child.

How is hypothyroidism diagnosed?

Hypothyroidism can be diagnosed by simple blood tests:

• TSH and T4

If thyroid is not working properly (which is called primary hypothyroidism), pituitary tries to stimulate its function by increasing TSH. So initial stages of primary hypothyroidism, TSH is high and T4 is normal. This is called subclinical hypothyroidism. If thyroid is damaged further, TSH goes higher and T4 starts getting lower.

If pituitary is not working well, TSH levels are not increased appropriately and T4 is low. This is called secondary hypothyroidism.

How is hypothyroidism treated?

Thyroxine (T4) replacement.

• Hypothyroidism cannot be cured but can be completely controlled.
• It is treated by replacing the amount of hormone that your own thyroid can no longer make, to bring your T4 and TSH back to normal levels.
• Pure, synthetic thyroxine (T4) works in the same way as a patient’s own thyroid hormone would. Therefore, taking thyroid hormone is different from taking other medications, because its job is to replace a hormone that is missing.
• The only safety concerns about taking thyroid hormone is taking too much or too little. Your thyroid function will be monitored by your physician to make sure this does not happen.
• Because it stays in your system for a long time, it is taken just once a day.
• When thyroid hormone is used to treat hypothyroidism, the goal of treatment is to keep thyroid function within the same range as people without thyroid problems. Keeping the TSH level in the normal range does this.
• The best time to take thyroid hormone is first thing in the morning on an empty stomach. This is because food in the stomach can affect the absorption of thyroid hormone.
• If you are taking several other medications, you should discuss the timing of your thyroid hormone dose with your endocrinologist.
• Do not stop your thyroid hormone without discussing this with your endocrinologist.
• Most thyroid problems are permanent, and therefore most patients require thyroid hormone for life.
• If you miss a dose of thyroid hormone, it is usually best to take the missed dose next day morning.
• It is very important that your TSH levels are checked periodically, even if you are feeling fine, so that your dose of thyroid hormone can be adjusted if needed.

Does thyroid hormone interact with any other medications?

Taking other medications or products can sometimes cause people to need a higher or lower dose of thyroid hormone: birth control pills, estrogen, testosterone, some anti-seizure medications, some medications for depression, iron, calcium, soy and some cholesterol-lowering medications.
For all these reasons, it is important for people taking thyroid hormone to keep their doctor up to date with any changes in the medications or supplements they are taking.

Should I take thyroid hormone while I am pregnant?

Since thyroid hormone is a hormone normally present in the body, it is absolutely safe to take while pregnant. In fact, it is very important for pregnant women, or women who are planning to become pregnant, to have normal thyroid function to provide the optimum environment for her baby. Get your TSH checked when you plan pregnancy. Women who are taking thyroid hormone often need an increased dose of thyroid hormone during their pregnancy, one needs to check free T4 and TSH regularly (usually monthly) during pregnancy.