Underactive thyroid
An underactive thyroid (hypothyroidism) means the thyroid gland in the neck does not make enough thyroid hormone, so the body slows down. It is more common in women and in areas with iodine deficiency, and it can also start after childbirth. It is easy to diagnose with a blood test and is treated well with one tablet a day.
Symptoms
- Tiredness and sleepiness
- Feeling cold when others do not
- Weight gain
- Constipation
- Dry skin and hair loss
- Low mood and slow thinking
- Heavy or irregular periods
- Swelling in the neck (goitre) in some people
Causes
- The immune system attacking the thyroid (Hashimoto disease), the most common cause
- Too little iodine in the diet
- After thyroid surgery or radioactive iodine treatment
- Some medicines
- After childbirth (usually temporary)
Prevention
- Use iodised salt at home
- The autoimmune type cannot be prevented, but early testing helps
- Ask for a thyroid blood test if you have symptoms, are planning a pregnancy, or thyroid disease runs in your family
Treatment
- A levothyroxine tablet once a day, usually for life
- Take it on an empty stomach, 30 to 60 minutes before breakfast, and apart from iron or calcium tablets
- A blood test (TSH) after 6 to 8 weeks to adjust the dose, then usually once a year
- Pregnant women need early testing and often a higher dose
- Do not stop or change the dose without a doctor
Common questions
Do I have to take the tablet for life?
Usually yes. Levothyroxine replaces a hormone your body no longer makes enough of. At the right dose it is safe long term, including in pregnancy and breastfeeding.
Can thyroid disease stop me getting pregnant?
Untreated thyroid problems can cause irregular periods, make pregnancy harder and affect the baby. With treatment and regular blood tests, most women have healthy pregnancies.