Hypothyroidism is a disease characterized by the reduced functional activity of the thyroid gland and a decrease in the level of hormones it produces.
The thyroid gland, shaped like a butterfly, is located in the central part of the neck. This gland secretes and releases hormones T4, or thyroxine, and T3, or triiodothyronine. These hormones are involved in the body's growth, maintenance of most bodily functions, and the regulation of metabolism.
Because these thyroid hormones are involved in many body processes, hypothyroidism can cause health issues such as decreased heart rate, intestinal disorders, weight gain, depression, decreased fertility, etc.
Causes of Hypothyroidism
The most common cause is Hashimoto's disease or chronic thyroiditis, an inflammation of the thyroid gland. These health issues are caused by a reaction of the immune system against the thyroid gland.
The inflammation damages the gland's cells, which causes changes in the production of hormones. It can happen at any age, but is most often seen in middle-aged women.
Thyroidectomy, a thyroid removal surgery done for thyroid cancer or nodules, can also cause hypothyroidism. See a full list of symptoms for hypo and hyperthyroidism here.
Another possible origin may be postpartum thyroiditis, which is asymptomatic. Thyroiditis causes hyperthyroidism followed by hypothyroidism, and in 80% of cases, it's cleared after a year.
Hypothyroidism can also be congenital—detected by heel prick testing and effectively treated shortly after birth.
There are risk factors that increase the chances of hypothyroidism in an individual:
- Family history of endocrine problems or goiter.
- Being over 50 years old.
- Having an autoimmune disease that attacks thyroid cells and their enzymes.
- Having undergone radiation to the neck or head to treat cancer.
- Undergone some treatments such as lithium or amiodarone.
- Low or excessive iodine diet: Iodine is necessary to synthesize thyroid hormones. In excess, it can damage the gland.
- Sheehan's syndrome affects the pituitary gland after severe bleeding during childbirth.
Symptoms of Hypothyroidism
- Reduced heart rate, irregular heartbeat, or arrhythmia. It could cause bradycardia, which, in extreme cases, can lead to cardiac arrest.
- Low blood pressure and cholesterol.
- Decreased levels of liver enzymes.
- Fatigue and sleepiness.
- Muscle and joint pain.
- Weight gain due to fluid retention.
- Constipation or hard stools.
- Altered menstrual periods and fertility problems.
- Weak skin, hair, and nails.
- Swollen face, hands, and feet.
- Low libido.
Prevention of Hypothyroidism
There is no known way to entirely prevent hypothyroidism. The only prevention is to control the level of iodine in our diet and adjust it to the recommended level.
The thyroid gland needs iodine to make enough hormones. A good way to increase iodine intake is to consume iodized salt.
Types of Hypothyroidism
The most common type of hypothyroidism. The thyroid gland doesn’t function properly, causing a goiter. This is an abnormal enlargement of the thyroid gland seen in the neck.
This type of thyroid does not show any symptoms, but it causes the pituitary gland to stop producing thyroid-stimulating hormones (thyrotropin or TSH). This leads to inadequate secretion of thyroid hormones.
It affects the hypothalamus, a region of the brain responsible (among other things) for secreting thyrotropin-releasing hormone (TRH). This secretion stimulates the pituitary gland to release thyrotropin (TSH), which, in turn, is responsible for stimulating the thyroid gland. It causes a chain reaction that alters the function of both the pituitary gland and the thyroid gland.
Diagnosis of Hypothyroidism
When hypothyroidism is suspected, the most effective way to confirm the diagnosis is to perform a blood test to measure the levels of TSH and thyroxine.
Likewise, the levels of cholesterol, liver enzymes, prolactin, and sodium are analyzed. The hemogram measures the composition of each of the cellular elements of the blood—white and red blood cells and platelets. It also checks if they have a normal shape and structure.
If there is a goiter (enlarged thyroid), it may be advisable to perform a thyroid ultrasound.
In certain cases, when it's believed that there could be alterations in the development of the gland or an enzyme deficiency, performing a thyroid scan can be very useful.
Treatments of Hypothyroidism
Treatment depends on the severity of the disease, the patient's age, and the existence of other health issues.
In general, treatment is the oral administration of the drug levothyroxine. Levothyroxine replenishes the level of thyroid hormones that the patient should have. The dose will vary depending on the needs of each patient.
The patient will need to undergo check-ups every two to three months during the beginning of treatment to check their hormone levels. They will have to continue taking levothyroxine and have periodic check-ups, usually once a year. Except for a few cases where hypothyroidism is a chronic condition, treatment will be life-long.