What you need to know about Hypothyroidism

Today I want to talk about a quite common disease in the endocrinology clinic (much more than people think), of which everyone has heard... We will talk about hypothyroidism.

Source

Hypothyroidism occurs when there is a decrease in thyroid hormones in the blood. These hormones are produced by the thyroid, a butterfly-shaped gland located in the front of the neck, and are of great importance in the metabolism and in health in general. They maintain the rhythm with which the body uses carbohydrates and fats, regulate protein production, maintain basal metabolism (and with it, temperature), influence heart rate and many other bodily activities. The disorder is much more frequent in women than in men.

Classification

• Primary hypothyroidism: when the dysfunction is in the thyroid gland itself, that is, the gland is unable to synthesize enough hormones (more than 90% of hypothyroidism cases are of this type).

• Secondary hypothyroidism: the thyroid gland is normal but the failure is in the pituitary gland that produces an insufficient amount of thyroid stimulating hormone or thyrotropin (TSH), which causes inadequate thyroid stimulation.

• Tertiary hypothyroidism: there is also a normal thyroid gland but in this case the failure is at the level of the hypothalamus, which produces an inadequate amount of thyrotropin-releasing hormone (TRH), leading to an insufficient TSH release.

Causes

• Autoimmune Etiology: Chronic autoimmune thyroiditis (Hashimoto's disease) is the most common cause of hypothyroidism in areas with iodine sufficiency. It is a chronic inflammation of the gland, with production of antibodies that attack it and that eventually leads to the destruction of thyroid cells.

• Iodine deficiency: it is the most frequent cause worldwide, especially in less developed countries (iodine is essential for the synthesis of thyroid hormone). The addition of iodine to table salt has decreased the occurrence of hypothyroidism.

• Iatrogenic: occurs when patients with hyperthyroidism receive an excessive dose of antithyroid drugs.

• Postoperative: it occurs in all cases of total thyroidectomy and in some of subtotal thyroidectomies.

• After receiving radioactive iodine or head and neck radiation.

• Secondary to drugs such as lithium and amiodarone.

• After infiltrative thyroid diseases: sarcoidosis, hemochromatosis, amyloidosis, Riedel's thyroiditis.

• Thyroid agenesis or dysgenesis, which can occur as ectopia (wrong location of the gland), aplasia or hypoplasia (incomplete development of the gland). They are nothing more than alterations in the embryological development of the thyroid, which lead to congenital hypothyroidism.

Risk factor's

Although anyone can develop hypothyroidism, the following factors confer additional risk of suffering from it:

• Female sex, especially women over 60 years.
• Having another autoimmune disease (Type 1 Diabetes Mellitus, Rheumatoid Arthritis, Lupus, Vitiligo, etc).
• Have a family history of thyroid disease.
• Having received radiation in the head and neck.
• Pregnancy.
• Having had thyroid surgery.

Symptoms and signs

The clinical signs of hypothyroidism begin insidiously, symptoms rarely occur early, are sometimes nonspecific, and are attributed to aging or stress. They vary according to the severity of the hormonal deficiency. Among the most common signs and symptoms we have:

• Lethargy, fatigue, lack of energy.
• Memory disorders, slowness of speech (bradylalia) and thought (bradypsychia).
• Weight gain.
• Sleep disorders, especially drowsiness.
• Hair loss, nails and brittle hair.
• Dry and thickened skin.
• Headache.
• Muscle aches and weakness, joint pain.
• Depression.
• Constipation.
• Intolerance to cold and decreased sweating.

Source

• Paleness.
• Swelling (edema) on the face, around the eyes and the tongue.
• Abundant or irregular menstrual periods and infertility (since it affects ovulation), decreased libido.
• Slowing of the heart rate (bradycardia.)
• Decrease and slow down of the osteotendinous reflexes.
• Hypertension.
• Decreased left ventricular stroke volume.
• Electrocardiogram disorders (PR prolongation, low voltage QRS complex and even atrioventricular block).
• There may be an increase in the size of the gland (goiter), due to the continuous stimulation of the gland (by thyroid stimulating hormone or TSH) to try to produce hormones.
• There may be anemia and high cholesterol levels.
• When hypothyroidism is prolonged (without treatment) it can reach a serious condition that puts at risk the life of the patient called myxedema coma.

Diagnosis

The diagnosis is confirmed mainly through the determination of TSH values (which will be elevated and is the most sensitive test for diagnosis) and free T4 (which will be low).

The presence of antithyroid antibodies must also be determined (antibodies against thyroid peroxidase or anti-TPO and antithyroglobulin)
There is a condition called subclinical hypothyroidism (quite common), in which TSH is elevated, but the values of T3 and T4 are still within normal.

Imaging Studies

Although of little use in hypothyroidism per se, a thyroid ultrasound should be performed in all patients in whom hypothyroidism is diagnosed, in order to detect the presence of nodules or infiltrative diseases if they are suspected.

Treatment

The treatment for hypothyroidism consists of the administration of levothyroxine (thyroid hormone) daily orally. The dose is individualized according to laboratory results and other clinical parameters and may take some time to reach the appropriate dose. Symptoms improve approximately after the first week with treatment.

It should not be administered in relation to food or drinks because it reduces its absorption, so the patient is recommended to take it on an empty stomach and wait at least half an hour for breakfast.

Levothyroxine is a safe and effective drug, it allows you to continue with a normal lifestyle. Usually, hypothyroidism requires lifelong treatment.

There is controversy as to whether subclinical hypothyroidism should receive treatment, however, I personally agree, especially in those patients who are symptomatic, pregnant, have high cholesterol levels or anemia, patients with marked smoking habit, have a goiter or have positive anti-thyroid antibodies.

A specific diet is not required in hypothyroidism.

Once the adequate dose is reached, the patient can be evaluated annually.

I hope the information has been useful, until next post

Reference:

1. https://emedicine.medscape.com/article/122393-overview