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Hypothyroidism (Underactive Thyroid)

Slowing of body metabolism caused by insufficient thyroid hormone production.

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Endokrinoloji department. Book Appointment →

What is Hypothyroidism (Underactive Thyroid)?

Hypothyroidism is a condition in which the thyroid gland produces insufficient quantities of the hormones T3 and T4. These hormones regulate metabolic rate, heat production, heart rate, and many organ functions, so a deficiency causes a wide range of symptoms affecting the whole body.

The most common cause is Hashimoto's thyroiditis, an autoimmune disease. Other causes include reduced thyroid tissue following thyroid surgery or radioactive iodine therapy, iodine deficiency, and certain medications (lithium, amiodarone).

Diagnosis is easily established by measuring TSH in a blood test. Treatment with a single daily dose of levothyroxine (synthetic T4) is highly effective; most patients can lead a completely normal life on therapy.

Symptoms

Fatigue, sleepiness, and weakness
Unintentional weight gain
Heightened cold intolerance
Constipation
Dry skin and brittle nails, hair loss
Slow heart rate (bradycardia)
Depression, difficulty concentrating, and forgetfulness

Risk Factors

Female sex (4-7× more common)
Age over 60
Family history of autoimmune thyroid disease
Type 1 diabetes or other autoimmune diseases
Prior thyroid surgery or radioactive iodine therapy
Pregnancy or the postpartum period
Lithium or amiodarone use

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Unexplained weight gain, fatigue, and cold intolerance
  • Elevated TSH on blood testing
  • For thyroid screening during pregnancy planning or pregnancy
  • If coma features develop in severe hypothyroidism (myxedema coma — emergency!)
  • Difficulty controlling levothyroxine dose or persistent symptoms

Treatment Methods

01
Levothyroxine (synthetic T4) tablets: taken in the morning on an empty stomach
02
Dose titration based on TSH (usual target TSH 0.5-2.5 mIU/L)
03
Dose requirements increase in pregnancy; close monitoring is essential
04
If symptoms persist despite therapy, addition of T3 (liothyronine) may be considered
05
Calcium, iron, and some medications are known to reduce levothyroxine absorption
06
Annual TSH monitoring to adjust the dose

Which Department to Visit?

You can visit our Endokrinoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.