Thyroid Disease: Symptoms, Causes, Diagnosis & Treatment

Last Updated on December 28, 2022 by Shabnam Sengupta

The thyroid gland is a small butterfly-shaped endocrine gland located over the trachea in the neck region. It is an extremely important gland for normal growth and functioning of the body because it produces a hormone called thyroxine. Thyroxine is of two types T3 and T4 and regulates the normal metabolism of the body. When there is disruption of the balance of the hormones or there is inflammation or malignancy in the thyroid organ the disease is collectively placed under thyroid diseases. Thus, thyroid disease is an umbrella term which includes mainly: 

1. Hyperthyroidism, in which excessive thyroid hormones are produced 
2. Hypothyroidism, in which an insufficient amount of hormones is produced 
3. Thyroiditis where inflammation of the gland is there
4. Hashimoto’s thyroiditis is an autoimmune disease affecting the thyroid gland 
5. Other conditions like thyroid malignancies, nodule formation, etc.

Here primarily we will focus on hyperthyroidism and hypothyroidism as they are the most common among the thyroid diseases.

Symptoms

For hypothyroidism:

Since thyroid hormones Triiodothyronine (T3) and tetraiodothyronine (T4) have the primary function of regulating the metabolism thus when they decrease the breakdown of complex molecules and energy production of the cell decrease leading to starvation of various cells causing:

1. Fatigue 
2. Lethargy 
3. Decreased appetite 
4. Forgetfulness 
5. Depression 
6. Excessive menstruation 
7. Weight gain 
8. Decreased heat production in the body causing intolerance to cold 
9. Dry skin
10. Thinning of hair 
11. Hoarse voice 

For hyperthyroidism:

1. Weight loss 
2. Increased appetite 
3. Anxiety and nervousness 
4. Decreased menstruation 
5. Excessive body heat production and heat intolerance 
6. Muscle weakness and tremors 
7. Insomnia 

Causes

The causes of hyperthyroidism include:

1. Inflammation of the thyroid gland (Thyroiditis):  this damages the thyroid cells increasing the amount of hormone released into the blood
2. Excessive iodine intake: increased iodine leads to increased thyroxine production 
3. Graves’ disease: this leads to the formation of autoantibodies which mimics Thyroid stimulating hormone leading to excessive stimulation of the gland and overproduction of the hormone
4. Nodules: toxic nodules overproduces the thyroid hormone 
5. Thyroid medicines: excessive consumption of thyroid medications causes too much conversion into thyroid hormone

Causes of hypothyroidism include:

1. Iodine deficiency: Iodine is needed for hormone production and hence less iodine means less thyroxine 
2. Congenital non-development of the organ: Thyroid organ can be partially or completely absent since birth causing developmental hypothyroidism 
3. Postpartum Thyroiditis: Post pregnancy causes the development of autoantibodies leading to thyroid damage 
4. Hashimoto’s thyroiditis: It’s an autoimmune disorder where antibodies damaging the thyroid organ get developed 
5. Over response to thyroid treatment: Anti-thyroid medicines when given in excessive doses can precipitate hypothyroidism 
6. Thyroid surgery: Complete or partial removal of the gland due to some other illness can decrease the amount of hormone in the blood 
7. Radiation therapy: This destroys the thyroxine-producing cells 

Risks factors

1. Positive family history 
2. Autoimmune diseases like SLE, Rheumatoid arthritis, Pernicious anemia etc
3. Increased age (over 60 years)
4. Female gender 
5. History of thyroid surgery or radiation
6. Intake of medicines rich in iodine and lithium 

Complications

For hypothyroidism:

1. Goitre: Enlargement of thyroid organ can occur due to excessive pituitary stimulation for a prolonged period of time.
2. Cardiovascular diseases: Hypothyroidism can lead to decrease in metabolism of lipids in the body which can increase the level of cholesterol and LDL predisposing the person to heart attack etc.
3. Infertility: Excessive weight gain causes altered hormonal levels and fertility in the female and can even cause birth defects 
4. Peripheral neuropathy: Long-term uncontrolled hypothyroidism damages the peripheral nerves causing pain and tingling sensations in the limbs.
5. Mental illnesses: Decreased mental functioning can lead to dementia and depression 

For hyperthyroidism:

1. Heart problems: Excessive stimulation of the heart can cause arrhythmia and fibrillations.
2. Brittle bones: Increased calcium metabolism can lead to weak bones.
3. Skin abnormalities seen in Graves’ disease.
4. Eye problems: Bulging of eyes along with light sensitivity is seen.

Diagnosis

For hypothyroidism tests done are:

1. Physical examination: slow pulse, decreased heart rate , weight gain, dry skin, hoarse voice etc
2. Blood tests: low levels of T3 and T4, high TSH levels, high cholesterol, LDL and HDL
3. Imaging studies usually ultrasound, and further tests if necessary
4. Iodine uptake tests: decreased uptake can be present 
5. Tests to check autoantibodies: autoantibodies found in case of Hashimoto’s thyroiditis 

For hyperthyroidism tests done are:

1. Physical examination: lean and thin body, increased heart rate, rapid pulse, enlarged organ, nervousness etc
2. Blood tests: increased levels of T3 and T4 with decreased levels of TSH seen 
3. Imaging studies: along with shape and size, it shows the presence of nodules if any 
4. Iodine uptake tests: increased uptake can be present 
5. Tests to check autoantibodies: found in case of Graves’ disease 

Treatment

For hyperthyroidism treatment options are:

The approach of the treatment includes decreasing the amount of thyroid hormones in the body either by medications or by surgery or by radiation:

1. Medicines: Carbimazole and propylthiouracil block the thyroid hormone production in the body
2. Surgery: partial or complete removal of the gland brings down the hormonal levels 
3. Radiation: the high energy rays cause destruction of the thyroid hormone-producing cells bringing down the hormone level 
4. Radioactive iodine therapy: this is a cytotoxic form of iodine so when it gets taken up by the thyroid cells they get killed decreasing the hormone levels 

For hypothyroidism treatment options are:

The approach of the treatment is to restore the normal level of thyroxine in the body thus Levothyroxine is given which is the synthetic form of the tetraiodothyroxine hormone which gets converted to T4 on consumption and helps to carry out all the functions of thyroid hormone.

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