Hypothyroidism: Symptoms, Causes and Treatment
Hypothyroidism - An underactive thyroid that makes too little hormone, slowing metabolism.
What is Hypothyroidism?
Hypothyroidism occurs when the thyroid gland in the neck does not produce enough thyroid hormone. This hormone controls metabolism, so low levels slow many body processes. It is more common in women and older adults. The most common cause in many countries is autoimmune thyroiditis (Hashimoto's), while iodine deficiency remains a cause in some regions.
Causes and Risk Factors
- Autoimmune thyroid disease
- Iodine deficiency
- Thyroid surgery or radioactive iodine treatment
- Some medicines such as lithium or amiodarone
- Pregnancy-related thyroid changes
Signs and Symptoms
- Tiredness and slowness
- Feeling cold
- Weight gain
- Dry skin and hair loss
- Constipation
- Low mood and poor memory
- Heavy or irregular periods
Red Flags: When to See a Doctor Urgently
- Extreme drowsiness, confusion and low temperature (rare myxoedema emergency)
- Rapid neck swelling with breathing or swallowing difficulty
Diagnosis: Tests, Lab and Imaging
A blood test measures TSH and free T4. A high TSH with low T4 confirms primary hypothyroidism. Thyroid antibodies may be checked.
Treatment and Medicines
Treatment is daily levothyroxine tablets, taken on an empty stomach. The dose is adjusted by blood tests every 6-8 weeks at first, then yearly.
Emergency
If you notice any red-flag sign, call 1122 (Pakistan), 911 (USA), 999 (UK) or 112 (Europe), or go to the nearest emergency department. See our emergency first aid guide.
Complications
Heart problems, infertility, pregnancy complications and, rarely, myxoedema coma.
Prevention
- Use iodised salt where iodine deficiency is common
- Screening in pregnancy or with symptoms
Outlook and Follow-up
With correct treatment, most people feel well and live normally.
Patient Education
Write down your questions before appointments, bring a list of all medicines, and ask what results mean for you. Use our symptom checker to learn which departments relate to your symptoms. This Hypothyroidism guide is educational and reviewed against WHO, CDC and NIH sources by the ghkh.site editorial team.
Frequently Asked Questions
Is treatment lifelong?
For most people, yes.
When should I take levothyroxine?
Usually in the morning on an empty stomach, 30-60 minutes before food, or as advised.
Can hypothyroidism cause weight gain?
Yes, mostly modest; treatment helps.
Sources
We summarise these sources in our own words. Mention of an organisation does not imply endorsement.