Hypothyroidism
قصور الغدة الدرقية
A condition in which the thyroid gland doesn't produce enough thyroid hormone, slowing down the body's metabolism. Common symptoms include fatigue, weight gain, cold intolerance, and dry skin. It's diagnosed with a blood test and usually well controlled with daily thyroid hormone replacement.
This information is for general awareness only and does not replace professional medical advice. Consult a doctor for diagnosis and treatment.
Quick answer
Hypothyroidism (underactive thyroid) means the thyroid gland does not make enough thyroid hormone, which slows down many of the body's processes.
Common symptoms include tiredness, feeling cold, weight gain, constipation, dry skin, low mood and slowed thinking. They develop gradually and can be mistaken for ageing or stress.
It is diagnosed with a blood test (TSH and thyroid hormone levels) and is usually treated with daily thyroid hormone replacement tablets prescribed and adjusted by a doctor. With treatment, most people feel well.
Symptoms
Tiredness and low energy
Feeling cold
Sensitivity to cold when others are comfortable.
Weight gain
Usually modest.
Constipation
Dry skin and thinning hair
Low mood or depression
Slowed thinking or poor concentration
Muscle aches and joint stiffness
Heavier or irregular periods
Swelling in the neck (goitre)
In some people the thyroid gland enlarges.
Causes and risk factors
Causes
- Autoimmune thyroiditis (Hashimoto's disease) — The immune system attacks the thyroid; the most common cause in many countries.
- Treatment for an overactive thyroid — Radioactive iodine, anti-thyroid medicines or thyroid surgery can lower hormone levels.
- Thyroid surgery or radiotherapy to the neck
- Iodine deficiency — A cause worldwide where diets lack iodine.
- Some medicines — A few drugs can interfere with thyroid hormone production.
- Present from birth — Some babies are born with an underactive thyroid, which is why newborns are screened.
Risk factors
- Being female
- Older age
- Family history of thyroid disease
- Other autoimmune conditions — For example type 1 diabetes or coeliac disease.
- Previous thyroid treatment or neck radiation
- Pregnancy and the period after childbirth
How is it diagnosed?
Hypothyroidism is diagnosed with blood tests. Symptoms alone are not enough because they are common and non-specific.
TSH test
Thyroid-stimulating hormone is usually raised when the thyroid is underactive.
Free T4 (and sometimes T3)
Measures the thyroid hormones themselves.
Thyroid antibody tests
May be done to look for an autoimmune cause.
Ultrasound
Occasionally used if there is a lump or enlarged thyroid.
Related tests
Treatment
Hypothyroidism is usually treated by replacing the missing hormone with levothyroxine tablets. The dose is individual and adjusted by your doctor using blood tests.
Thyroid hormone replacement
Usually taken once daily, often for life. The dose is set and adjusted by a doctor based on blood tests and symptoms.
Regular blood tests
TSH is checked after starting or changing treatment, then periodically.
Taking medicine consistently
Follow your doctor's or pharmacist's advice on timing relative to food and other medicines or supplements.
Do not adjust your dose on your own, and do not use thyroid tablets for weight loss.
When should you see a doctor?
Arrange a medical assessment if
- Persistent tiredness, cold intolerance, weight gain or constipation without another explanation
- A swelling or lump in the front of the neck
- Symptoms that continue despite treatment, or new symptoms after a dose change
- You are pregnant or planning pregnancy and have a thyroid condition
- Low mood that is affecting daily life
Seek urgent care if
- Severe drowsiness, confusion or unresponsiveness, especially with very low body temperature
- Slow breathing or a very slow heartbeat
- Chest pain or severe shortness of breath
Prevention
Adequate iodine intake
Iodine deficiency is preventable; iodised salt is widely used for this purpose. Do not take iodine supplements without medical advice.
Screening in high-risk groups
Newborn screening, and testing if you have a strong family history or other autoimmune disease, helps detect it early.
Keep follow-up appointments if you have had thyroid treatment
Frequently asked questions
What is hypothyroidism?
It is a condition in which the thyroid gland does not produce enough thyroid hormone, slowing the body's metabolism.
What are the symptoms of an underactive thyroid?
Tiredness, feeling cold, weight gain, constipation, dry skin, low mood and slow thinking are common.
How is hypothyroidism diagnosed?
With blood tests measuring TSH and thyroid hormone levels.
Is hypothyroidism curable?
In most people it is lifelong, but treatment with hormone replacement controls it very effectively. Some temporary forms resolve on their own.
Does hypothyroidism cause weight gain?
It can cause modest weight gain, partly from fluid. Treatment may help, but it is not a weight-loss treatment.
Can hypothyroidism affect pregnancy?
Yes. Untreated or poorly controlled hypothyroidism can affect pregnancy, so doctors monitor thyroid levels and may adjust treatment.
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Medical sources
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