Hypothyroidism
What is Hypothyroidism (Underactive Thyroid Function)?
In hypothyroidism, the production of thyroid hormones (thyroxine) is impaired.
Common Causes
Hashimoto's Thyroiditis – An autoimmune condition where the body's immune system attacks the thyroid gland, leading to decreased function.
Iodine Deficiency – Iodine is essential for the proper synthesis of thyroid hormones.
Postpartum Thyroiditis – A decrease in thyroid function following childbirth.
Genetic Factors – A family history of thyroid disorders may increase the risk.
Medications – Certain drugs, such as lithium and amiodarone, can affect thyroid function.
Total Thyroidectomy or Radioactive Iodine Treatment – Surgical removal of the thyroid gland or treatment with radioactive iodine can lead to hypothyroidism.
Symptoms
Symptoms of hypothyroidism may include:
Fatigue
Cold intolerance
Constipation
Dry skin
Weight gain
Facial puffiness
Changes in voice tone
Coarse hair and skin
Muscle weakness
Muscle pain and stiffness
Heavy or irregular menstrual cycles
Hair loss
Slow heart rate (bradycardia)
Depression
Memory problems
Diagnosis
Laboratory Tests:
Thyroid-Stimulating Hormone (TSH)
Thyroid Hormones (FT4, FT3)
Antibodies (Anti-TPO, Anti-Tg)
TSH measurement also plays an essential role in managing hypothyroidism. Based on TSH results, the doctor determines the appropriate dosage of medication.
Certain medications and supplements, such as biotin, which is found in multivitamins, can affect test results. Before undergoing testing, consult your doctor about any medications or supplements you are taking.
Treatment
Hypothyroidism is typically treated with levothyroxine, which is taken daily. This medication restores thyroid hormone levels and alleviates hypothyroid symptoms.
Most people begin to feel better within one to two weeks of starting treatment. Levothyroxine therapy is usually lifelong.
Is the Dosage Correct?
To determine the correct dose of levothyroxine, your doctor will check your TSH levels 6–8 weeks after starting treatment.
Taking too much levothyroxine may cause side effects such as:
Fatigue
Increased appetite
Sleep disturbances
Heart palpitations
How to Take Levothyroxine Correctly
Take levothyroxine on an empty stomach, ideally at the same time every day—30–60 minutes before breakfast or before taking other medications.
If taken at night, ensure at least 4 hours have passed since your last meal.
Do not skip doses or stop the medication because you feel better. If you stop taking it, hypothyroid symptoms will gradually return.
If you miss a dose, take two pills the next day.
Medications and Supplements That Affect Levothyroxine Absorption
Consult your doctor if you take any of the following, as they may interfere with levothyroxine absorption:
Iron supplements or iron-containing multivitamins
Aluminum hydroxide, found in antacids
Calcium supplements