Thyroid Medication: Types And Dosage

The thyroid gland is located in the neck and is responsible for metabolism and other bodily functions. Lupus, also known as systemic lupus erythematosus (SLE), is an autoimmune illness in which the body's immune system attacks its own tissues and organs which causes thyroid dysfunction.

It is estimated that 6% of lupus patients have hypothyroidism (underactive thyroid) and 2% have hyperthyroidism (overactive thyroid). A malfunctioning thyroid gland can impair organ function, including the brain, heart, kidneys, liver, and skin. The treatment for both underactive and hyperactive thyroid involves restoring the body's metabolism to normal.

This article delves into thyroid medication, its types, dosage and additional lifestyle remedies.

Types of Thyroid Medications

Thyroid medications are available as pills and require a doctor's prescription. If a person is diagnosed with hypothyroidism, then the person may be offered medication to replace the hormones generated by the thyroid gland.

• Levothyroxine is a medicine for hypothyroidism that substitutes the hormone thyroxin (T4).
• Liothyronine, which substitutes the hormone triiodothyronine (T3), is often recommended only after a thorough examination by a thyroid expert (endocrinologist).

There are various thyroid medications that can help to treat hyperthyroidism. They include carbimazole and propylthiouracil. These drugs decrease hormone production in the thyroid gland and help to fight the disorder.

The  Mechanism of Action in Thyroid Medications

Thyroid medications work by either replacing or blocking thyroid hormone production: 

• In Hypothyroidism

Thyroid medications replace thyroid hormones that the body cannot produce in the right amounts.

• In Hyperthyroidism

Thyroid medications block the production of thyroid hormones, which the body produces too much of. Antithyroid medications (ATDs) work by blocking the thyroid gland components such as tyrosine residues in thyroglobulin. This activity inhibits thyroid peroxidase (TPO) from adding iodine, and reduces the formation of thyroid hormone.

Dosage and Administration of Thyroid Medication 

The recommended dosage and instructions for administering thyroid medication are as follows:

Usual Adult Dose for Hypothyroidism

The dosage is 30 mg taken orally once a day on an empty stomach. Then, it should be increased by 15 mg per day for 2 to 3 weeks to reach normal serum T3 and T4 levels.

Usual Adult Dose for Thyroid Cancer

For follicular and papillary thyroid cancer, taking higher doses than recommended for replacement treatment (30 mg to 120 mg per day) is necessary. 

Usual Pediatric or infant Dose for Hypothyroidism

In children, as in adults, the medication is administered orally on an empty stomach:

• 0 to 6 months: 4.8 to 6 mg/kg/day
• 6 to 12 months: 3.6 to 4.8 mg/kg/day
• 1 to 5 years: 3 to 3.6 mg/kg/day
• 6 to 12 years: 2.4 to 3 mg/kg/day
• >=12 years: 1.2 to 1.8 mg/kg/day

What are the Potential Side Effects of Thyroid Medication?

Thyroid medications can have multiple side effects if not taken correctly. Adverse effects may include:

• Diarrhoea
• Trouble sleeping
• Increased appetite
• Feeling nervous
• Tiredness

If a patient is administering thyroid medicines to manage hyperthyroidism, common side effects may include:

• Vomiting
• Stomach discomfort
• Nausea
• Rash 

If a person is suffering from any of these impacts from thyroid medication, then they should consult the doctor immediately.

The Interactions with Other Medications in Thyroid 

Medicines for managing various unrelated conditions can sometimes directly affect thyroid function. The most typically implicated medicines are amiodarone and lithium.

Amiodarone

Because of its high iodine concentration, amiodarone, a drug often used to treat cardiac rhythm disorders, has complicated effects on thyroid function. It has been linked to both hyperthyroidism and hypothyroidism.

Amiodarone prevents the conversion of thyroxine (T4) to triiodothyronine (T3) in the body. Because T3 is the active thyroid hormone, this causes reduced amounts of the active hormone. This impact can worsen the symptoms of persons who already have hypothyroidism.

As a result, amiodarone is not suggested (contraindicated) for anyone with present or previous thyroid disorders.

Lithium

This medication can cause clinical hypothyroidism by directly affecting the thyroid gland and blocking the release of thyroid hormones. This can worsen the condition in individuals who already have hypothyroidism and is therefore not suitable for them.

The Role of Diet and Lifestyle Changes in Thyroid Health

Adopting preventive strategies, including proper nutrition and healthy lifestyle habits can lower the risk of thyroid disorders and support optimal thyroid function for overall well-being. Below are some useful tips:

• Eating a Balanced Diet

Thyroid health requires a well-balanced and nutritional diet. Including foods high in iodine, such as seaweed, seafood, dairy, as well as iodised salt, can promote thyroid function. Zinc found in whole grains, nuts, and lean meats can enhance hormone synthesis.

• Monitoring Iodine Intake

While iodine is necessary for thyroid function, both excess and lack of it can be harmful. Hence, one must be aware of the daily iodine intake. For specific guidance, it is better to consult a doctor or an endocrinologist.

• Managing Stress

Chronic stress can impair thyroid function. Stress-relieving activities such as deep breathing exercises,  yoga, meditation, or hobbies can help a person balance their cortisol levels and thereby improve thyroid health.

• Limiting Environmental Toxins

Pollution, chemicals, and heavy metals are all environmental toxins that can disrupt thyroid function. To reduce exposure, one can opt for natural cleaning products and be aware of environmental pollution.

• Prioritising Regular Check-Ups

Regular check-ups are required for early diagnosis of any potential thyroid problems. If a person experiences overactive or underactive thyroid symptoms, the doctor may advise a thyroid function test to detect anomalies and give proper medication.

Thyroid Medication During Pregnancy and Breastfeeding

Pregnant women are usually treated with the antithyroid medication propylthiouracil (PTU) during the first trimester. Methimazole (MMI), another antithyroid medication, is simpler to administer and causes fewer side effects; it has a slightly higher risk of causing congenital abnormalities compared to PTU.

Minimal amounts of antithyroid medication can enter the baby's bloodstream, potentially reducing the baby's thyroid hormone levels. To avoid this, doctors prescribe the lowest effective dose to manage the mother's elevated thyroid hormone levels while avoiding hypothyroidism (underactive thyroid) in the baby.

This careful balance is important because both untreated high thyroid hormone levels and low levels can affect the baby’s health.

Treatment of Older People with Thyroid Medication

Older patients with hypothyroidism require treatment with levothyroxine, starting with 25 to 50 mcg daily and increasing cautiously every 4-6 weeks until thyroid hormones and TSH levels return to normal.

Therefore, older people with no symptoms of heart disease, stroke, or dementia may begin with higher dosages and progress to full hormone replacement more rapidly.

Conclusion

Thyroid diseases need a comprehensive treatment that involves proper diagnosis, medicine, and better lifestyle choices. Thyroid medicines, such as levothyroxine for hypothyroidism and antithyroid treatments, can help control hormone levels and restore metabolic balance in the body.

By implementing medical treatments, preventive measures, and frequent health check-ups, a person may enhance overall health and manage thyroid-related disorders.