What is hypothyroidism?

Hypothyroidism means underactive thyroid gland that lacks the ability to grant the body vital hormones. In fact, the decrease in secretion of thyroid hormones into the blood stream causes a slow metabolism. Therefore, a hypothyroid patient will suffer from fatigue, weight gain, and difficulty coping with low temperature. Although such symptoms are not visible from the beginning, if hypothyroidism is ignored it will cause obesity, heart problems, infertility and more. Also, hormone replacement therapy is the main treatment, and your doctor will prescribe the right dose for you.

What causes hypothyroidism?

There's many causes behind this disease which proposes a primary and secondary classification.

Primary hypothyroidism causes:

Usually, the primary type occurs when the thyroid gland is incapable of producing enough thyroid hormones.

• Hashimoto's disease: Or Hashimoto thyroiditis is an autoimmune thyroid disease widely prevalent in regions rich with iodine such as the United States. Besides, it is highly linked to lymphoma.
• Iodine deficiency: The loss of iodine in the body causes hypothyroidism, since thyroid hormone cannot be produced without iodine. Moreover, it affects people living in areas having iodine deficiency, and it's the most common cause worldwide.
• Drugs medication: this includes lithium, interleukin-2, interferon, rifampin, phenobarbital, oral tyrosine kinase inhibitors and others. Hence, consult with your doctor the side effects of such medications.
• Thyroid radioactive iodine therapy: it's a method to treat hyperthyroidism and stabilize thyroid hormones levels. However, it is possible to become permanently hypothyroid if correcting hyperthyroidism leads to too much reduction of thyroid hormone production.
• Head/neck radiotherapy: radiotherapy is applied as a cancer treatment of the neck and head, but it may cause hypothyroidism.
• Thyroid surgery: the removal of your entire thyroid gland, or a substantial portion, can affect hormone production. Consequently, you'll need to take thyroid hormone for the rest of your life.
• Quervain disease: or subacute granulomatous thyroiditis, is a disease that targets middle-aged women and typically self-limiting.

Secondary/Tertiary hypothyroidism causes:

The less common form, secondary hypothyroidism, is caused by a pathology in the pituitary gland or hypothalamus, while the thyroid gland is normal.

• Pregnancy: after giving birth, about 3 in every 100 mothers will have an inflammation of the thyroid gland "Postpartum thyroiditis". This is due to the production of antibodies against their own thyroid gland "autoimmunity".
• Pituitary or hypothalamus disorders: a low thyroid hormone level results from insufficient thyroid releasing hormone (TRH) released by the hypothalamus, which then stimulates the anterior pituitary to release thyroid stimulating hormone (TSH).
• Tumor: this includes pituitary gland tumor, which leads to its inability to produce thyroid-stimulating hormone (TSH).
• Brain radiation therapy: radiation therapy can lead to hypothyroidism in nearly half of patients with head cancer. This can occur years after the end of the treatment.
• Thyroid releasing hormone (TRH) resistance: it is a rare condition where a mutation inactivates TRH receptor gene.
• Sheehan syndrome: postpartum hypopituitarism leads to postpartum steroid hormone decrease which triggers autoimmune thyroid diseases.

Common causes:

• Cancer medication: treatment with anti-CTLA-4 and anti-PD-L1/PD-1 medications has emerged as a new class of cancer medications that causes hypothyroidism.

Hypothyroidism Symptoms:

Common symptoms:

• Cold weather intolerance
• Fatigue
• Weight gain
• Dry skin
• Dull face
• Eyes puffiness
• Sweating less
• High cholesterol levels
• Hair loss
• Coarse hair
• Voice changes or hoarseness
• Fullness of throat
• Constipation
• Muscle aches
• Insomnia
• Irregular menstrual cycle
• Milky nipple discharge or galactorrhea
• Depression and anxiety
• Psychosis
• Memory loss
• Bradycardia
• Thyroid gland enlargement
• Periodic neck pain and/or sore throat

Rare symptoms:

• Building up of fluids in the abdomen "ascites"
• Shoulders, lower back and thighs muscle pain "rhabdomyolysis"
• Pericardial effusion

Symptoms of infants with hypothyroidism:

• Jaundice
• Hoarseness while crying
• A tongue that sticks out large
• Breathing difficulties
• Umbilical hernia

Hypothyroidism risk factors:

• Gender: women are more likely to acquire the disease.
• Age: women over 60 years old are at a higher risk.
• Family history: parents who has hypothyroidism.
• Radiation therapy: In patients who have had head and neck irradiation in the past.
• Autoimmunity: positive thyroid peroxidase antibodies.
• Pregnancy: mostly Hashimoto's disease.

When to see a doctor?

Without doubt, see a doctor if you are always tired without doing any effort or has any of the symptoms mentioned before. Such signs mostly include puffy, dull face, voice changes and constipation. Furthermore, follow-up visits with your doctor is necessary since this is a life threatening disease. Meanwhile, you can control hypothyroidism by taking the correct dose prescribed by your doctor, and the dose may change with time.

How to lose weight with hypothyroidism?

In the absence of treatment for hypothyroidism, you may gain weight. However, once you treat the disorder, the weight should slowly decrease. Even so, you will still have to watch your calorie intake and exercise to lose weight. Consult your physician about weight loss and a diet you can follow.

Diagnosis:

Blood test is the mainstay for diagnosing hypothyroidism. To illustrate, most patients are screened for hypothyroidism based on their serum TSH levels. Patients with severe hypothyroidism have elevated TSH levels and low free T4 levels; those with subclinical hypothyroidism (mild-moderate) have elevated TSH levels and normal free T4 levels. Not only it's the most trustworthy screening method for hypothyroidism, it also helps the doctor determine the suitable dosage to treat you. A thyroid disease screening should begin at age 35 and be repeated every five years, according to the American Thyroid Association, although there are no universal guidelines.

Treatment of hypothyroidism?

Monotherapy with levothyroxine (Synthroid, Euthyrox, Levo-T, etc...)  is the main treatment for hypothyroidism. This thyroid replacement with levothyroxine regulates thyroid hormones levels to be efficiently used by the body. In addition, the bad cholesterol will fall back to the normal range and weight loss takes place. As a matter of fact, the medication is a lifelong drug, but the dose can change according to annual TSH level test. In other words, you should never stop taking the medicine, and it's importance to consult your doctor once you switch to another brand. When taking levothyroxine at night, it is best to take it with at least four hours after the last meal. On the contrary, most people take it in the morning an hour before eating and taking other medications. Finally, do two levothyroxine pills the next morning if you miss a dose.

Complications of hypothyroidism:

• Goiter: In medical terminology, a goiter (GOI-tur) refers to an abnormal growth of the thyroid gland, which is located in the base of the neck just below the Adam's apple.
• Myxedema coma: As a result of severe hypothyroidism, myxedema coma can lead to hypothermia, reduced mental function, and other symptoms associated with slowed function in multiple organ systems. Also, myxedema coma is a life-threatening condition with a high mortality rate.
• Heart problems: Having an underactive thyroid may also increase the risk for heart disease or heart failure, mainly because an underactive thyroid increases the levels of LDL cholesterol or the bad cholesterol in the blood.
• Infertility: Hypothyroidism, and some of the causes of hypothyroidism, including autoimmune disorders, can impair ovulation and fertility.
• Obesity: Low thyroid hormones level leads to a slower metabolism that may result in obesity.
• Peripheral neuropathy: In severe cases of hypothyroidism, your peripheral nerves can be damaged.
• Defects at birth: Compared to babies born to healthy mothers, babies born to women who have untreated thyroid disease are more likely to suffer birth defects. Their intelligence is also more likely to be harmed.

References:

-Patil N, Rehman A, Jialal I. Hypothyroidism. [Updated 2022 Feb 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519536/

-Cleveland Clinic "Hypothyroidism"

-Mayo clinic "Hypothyroidism"

-Featured image credits: https://www.freepik.com/vectors/thyroid-gland