Hypothyroidism: Symptoms, Causes & Treatment Options

Hypothyroidism is one of the most common endocrine conditions and it is characterized by low thyroid activity, which causes it to produce fewer hormones, leading to the appearance of symptoms such as fatigue, decreased heart rate, increase in weight, hair loss, and dry skin.

This condition is more common in women over 40 years old who have close relatives with hypothyroidism, those who have had a part of or the whole thyroid removed, or those who have had some kind of radiation treatment to the head and neck.

Treatment for hypothyroidism is aimed at regulating thyroid hormone levels and thus relieving the symptoms. For this, endocrinologists usually prescribe synthetic hormones such as Levothyroxine. 

Hypothyroidism: Symptoms, Causes & Treatment Options

Signs and symptoms 

The signs and symptoms that can show your thyroid is underactive can appear gradually through the years according to the decrease in T3 and T4 hormone levels. The major signs and symptoms of hypothyroidism include:

  • Headache, muscle, and joint pain;
  • Irregular menstruation, which can cause trouble conceiving;
  • Fragile, breakable nails and dry, rough skin;
  • Swollen eyelids;
  • Hair loss and finer, dry, dull hair;
  • Slower heartbeat;
  • Constant fatigue;
  • Difficulty concentrating, and memory problems;
  • Low sex drive;
  • Increase in weight with no apparent cause.

In addition, there are cases where the person may undergo personality changes, depression, and dementia, however, these symptoms only happen in people who have very low levels of T3 and T4.

In children, hypothyroidism can also interfere with development, so in adolescence, puberty may come later and the child may not grow as much. In addition, if a baby has congenital hypothyroidism, and it is not detected in the first week after birth, the child may show signs of neurological problems.

Main causes

The most common cause of hypothyroidism is Hashimoto's Thyroiditis, which is an autoimmune disease where the body's antibodies start attacking the thyroid gland. In addition, hypothyroidism can also happen because of a deficiency in iodine, which is a condition known as goiter, in which there is an increase in thyroid size but a decrease in T3 and T4 production, due to low iodine concentration.

Treatment for hyperthyroidism or the use of some types of medication such as lithium carbonate, amiodarone, propylthiouracil, or methimazole can also lead to hypothyroidism, and it is thus important to visit an endocrinologist if any of these symptoms appear after starting using some kind of drug.

People who have taken thyroid medication to lose weight also can develop hypothyroidism because since these hormones are already present in the bloodstream, the thyroid may stop or decrease its natural production.

In addition to these causes, hypothyroidism can also happen during pregnancy or in the postnatal stage, but it usually goes back to normal after birth.


The best way to diagnose hypothyroidism is to consult an endocrinologist, in order to assess all signs and symptoms and do a blood test that checks for T3 and T4 levels, which are usually low in hypothyroidism, and TSH leves, which are usually high.

In addition, the doctor may also prescribe antibody tests, lymph node mapping and thyroid ultrasound.

When to do a thyroid blood test

If you have clear signs and symptoms of hypothyroidism or if you fall into one of the categories below, a thyroid blood test may be recommended: 

If you are a woman over 50 years old If you have had radiotherapy treatment on the head or neckIf you have Diabetes type 1
If you are pregnantIf you've done thyroid surgery If you have auto-immune diseases
If you have goiter If you have a family history of thyroid conditionsIf you have heart conditions
If you have Down Syndrome If you have Turner Syndrome If you're lactating and you're not pregnant or breastfeeding 

Treatment options

Treatment for hypothyroidism is relatively simple through hormonal replacement with synthetic hormones, such as levothyroxine. Levothyroxine should be taken when fasting, at least 30 minutes before breakfast, so that the food digestion does not decrease its effectiveness. An endocrinologist should prescribe the dose, and it can vary throughout treatment according to the levels of T3 and T4 circulating in the blood.

After 6 weeks of medication, the doctor may check your symptoms and request a TSH test to check whether you need to adjust the dose until the free T4 levels are normal. After that thyroid tests should be carried out once or twice a year, to check whether the medication doses need adjusting.

In addition to medication, it's important that the person control blood cholesterol levels, avoid eating fat, and do a diet that helps with the good functioning of the liver, and avoid intense stress, as this harms the secretion of hormones through the thyroid. In some cases, a check-up with a nutritionist may be recommended so that the nutrition treatment with an iodine supplement can help decrease the symptoms of hypothyroidism. 

With subclinical hypothyroidism, when there are no symptoms involved, the doctor may prescribe medications because these help decrease the risk of cardiovascular problems, which is important for people who are overweight or have high cholesterol or diabetes.

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  • SOCIEDADE BRASILEIRA DE ENDOCRINOLOGIA E METABOLOGIA. Hipotireoidismo: Sintomas. Available on: <http://www.tireoide.org.br/hipotireoidismo-sintomas/>. Access in 21 Feb 2020
  • McDERMOTT, Michael T. et al. Segredos em Endocrinologia. 5 ed. Rio de Janeiro: Elsevier, 2010. pp. 290-294.
  • SOCIEDADE BRASILEIRA DE ENDOCRINOLOGIA E METABOLOGIA. 10 Coisas que Você Precisa Saber sobre Hipotireoidismo. Available on: <https://www.endocrino.org.br/10-coisas-que-voce-precisa-saber-sobre-hipotireoidismo/>. Access in 21 Feb 2020
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