An underactive thyroid gland (hypothyroidism) is where your thyroid gland doesn’t produce enough hormones.
Common signs of an underactive thyroid are tiredness, weight gain and feeling depressed.
About Thyroid gland
Thyroid Gland: Size, Shape & Function
The thyroid is a butterfly-shaped endocrine (hormone secreting) gland in the neck that is found on both sides of the trachea (windpipe). It secretes the hormone Thyroxine which controls the rate of metabolism. Thyroid gland is one of the many endocrine glands such as adrenal, pituitary, pancreas, testes, etc.
The thyroid weighs about 20-25 gms in an adult. It is butterfly shaped and it consists of two lobes which are connected together by a median isthmus as shown in the picture. It is located in the front of the neck and is situated just below the larynx or the Adam’s apple.
The function of the thyroid gland is to take up iodine from the foods that we eat and to convert it into thyroid hormones namely Thyroxine (T4) and Triiodothyronine (T3) and Calcitonin (which is involved in calcium metabolism). The cells of this gland combine iodine and the amino acid tyrosine to make T3 and T4. Later T3 and T4 are then released into the blood stream and are transported throughout the body where they control the general metabolism (conversion of oxygen and calories to energy). The regulation of the metabolism of every cell in the body requires thyroid hormones. The ratio of production of T4 and T3 is 80:20. However, T3 is about 4 times more potent than T4.
The production of thyroid hormones is under direct control of the pituitary gland. Pituitary is an endocrine gland which is situated at the base of the brain and it secretes certain vital hormones which includes TSH (Thyroid stimulating hormone) or Thyrotropin, besides others. When the level of thyroid hormones (T3 and T4) falls below the required amount, the pituitary gland secretes TSH which stimulates increased production of T3 and T4. As the levels of T3 and T4 keep rising in the blood, the pituitary senses this and reduces TSH production.
The hypothalamus is that part of the brain which produces TRH (Thyrotropin Releasing Hormone). TRH regulates the production of TSH by the pituitary, i.e. it has a regulatory control over the pituitary gland.
Complications of Underactive thyroid
If left untreated, hypothyroidism can lead to several other health issues.
A goiter is an enlargement of the thyroid gland. The symptoms of goiter include:
• Swelling in the throat, ranging from a small lump to a huge mass.
• Swallowing problems, if the goiter is large enough to press on the oesophagus (food pipe).
• Breathing problems, if the goiter is large enough to press on the trachea (windpipe).
Hypothyroidism may also be associated with an increased risk of heart disease, primarily because high levels of low-density lipoprotein (LDL) cholesterol- the ‘bad’ cholesterol can occur in people with an Underactive thyroid. Hypothyroidism can also lead to an enlarged heart and heart failure.
It may lead to slowness of the mental activity. Depression may occur early in hypothyroidism and may become more severe over time.
This is a rare, life-threatening condition, which results due to prolonged, severe, untreated hypothyroidism. The symptoms include intense cold intolerance and drowsiness followed by profound lethargy and unconsciousness. The skin becomes dry and puffy.
A more severe condition referred to as Myxedema coma, if occurs in any case, would call for immediate medical help.
Concerning females and child birth related issues:
Infertility as well as miscarriage are the commonly encountered complications seen in females with untreated hypothyroidism. The babies born to women with untreated thyroid disease may have a higher risk of birth defects. These children are also more prone to serious intellectual and developmental problems.
Infants with untreated hypothyroidism present at birth are also at risk of serious problems with both physical and mental development. But if the condition is diagnosed within the first few months of life, the chances of normal development are excellent.