The thyroid in women: when tiredness is hypothyroidism
Hypothyroidism is a common condition in which the thyroid gland does not produce enough hormone. According to the NHS, the symptoms – severe tiredness, low mood, weight gain, feeling the cold – develop slowly and are easily put down to stress or depression. It is diagnosed with a blood test for TSH and thyroxine (T4), and treatment with levothyroxine allows a normal life.
- According to the NHS, the typical symptoms are severe tiredness, feeling the cold, weight gain, constipation, poor concentration, low mood or depression, dry skin and hair, hair loss, a hoarse voice and irregular or heavy periods.
- The main cause in the UK is Hashimoto's disease – an autoimmune condition that is most common in women and usually starts between the ages of 30 and 50.
- It is diagnosed with a blood test for thyroid-stimulating hormone (TSH) and thyroxine (T4).
- Treatment is with levothyroxine tablets, usually for life, with regular blood tests to check the dose.
- Untreated hypothyroidism raises the risk of heart and bone problems, and in pregnancy – of pre-eclampsia, premature birth and miscarriage.
Why is hypothyroidism mistaken for tiredness and depression?
According to the NHS, the symptoms of an underactive thyroid can be mild and hard to notice, and they usually develop slowly and get worse over time. This is exactly why many women take them for part of a busy daily life or for a sign of depression. Among the most common symptoms the NHS lists are:
- severe tiredness;
- feeling the cold more than usual;
- weight gain;
- constipation;
- poor concentration;
- low mood or depression;
- dry skin or hair, hair loss;
- a hoarse voice;
- irregular or heavy periods.
None of these signs on its own proves a thyroid problem – the NHS explicitly notes that the symptoms can have other causes too. That is why the only reliable route is a blood test.
Who is most at risk of an underactive thyroid?
Anyone can develop hypothyroidism, but according to the NHS the main cause in the UK – Hashimoto's disease – is most common in women and usually starts between the ages of 30 and 50. In Hashimoto's, the immune system attacks the thyroid gland itself. The risk is higher if close relatives have had a thyroid condition.
Other causes the NHS lists are inflammation of the gland (thyroiditis), surgery or radiotherapy to the neck area, treatment for an overactive thyroid, some medicines and – rarely in the UK – iodine deficiency.
What does the thyroid blood test show?
According to the NHS, the doctor first asks about your symptoms, a family history of thyroid conditions or autoimmune conditions, and any recent pregnancy. They may examine your neck for swelling. The decisive step is the blood test, which measures thyroid-stimulating hormone (TSH) and thyroxine (T4). If needed, the doctor may refer you to a specialist for further tests.
How is hypothyroidism treated and for how long?
Treatment, according to the NHS, is usually with levothyroxine tablets, which replace the missing hormone. They are usually taken for life, and with the right dose you can lead a completely normal life. Regular blood tests check whether the dose is right.
If the dose is not right, the NHS lists possible complaints such as feeling or being sick, diarrhoea, headaches or sleep problems – report them to your doctor or pharmacist so that it can be adjusted.
What does hypothyroidism mean when planning a pregnancy?
According to the NHS, if you have hypothyroidism and are pregnant or planning a pregnancy, you should tell your doctor. Extra tests will be needed, and the dose of levothyroxine will most likely have to be adjusted during pregnancy. The untreated condition can raise the risk of pre-eclampsia, birth defects, premature birth and miscarriage – but according to the NHS, treatment usually protects against these complications.
When should you see a doctor?
The NHS advises seeing your GP if you think you may have an underactive thyroid. This is not urgent, but it is important not to put it off, especially with:
- prolonged severe tiredness that does not go away with rest;
- low mood or depression combined with feeling the cold, weight gain or constipation;
- dry skin, hair loss or a hoarse voice with no other clear cause;
- irregular or heavy periods;
- relatives with a thyroid condition;
- an existing diagnosis and pregnancy or planning a pregnancy.
The NHS warns that the untreated condition or the wrong dose can raise the risk of heart problems (including coronary heart disease and heart failure) and bone problems such as osteoporosis. Very rarely, severe untreated hypothyroidism leads to myxoedema coma – a life-threatening condition that requires hospital treatment and is more common in older people.
Frequently asked questions
Can hypothyroidism be the cause of heavy or irregular periods?
Yes. The NHS lists irregular or heavy periods among the common symptoms of an underactive thyroid.
Will I have to take medicine for life?
According to the NHS, levothyroxine is usually taken for life, with regular blood tests to monitor whether the dose is right. With treatment you can lead a normal life.
Why is it important to tell the doctor if I am planning a pregnancy?
The NHS explains that during pregnancy the dose of levothyroxine will most likely need to be adjusted and extra tests are needed to reduce the risk of complications such as pre-eclampsia or premature birth.
Sources
- NHS – Underactive thyroid (hypothyroidism) – last reviewed by the NHS: 28 April 2025
Informational article retold in our own words from the sources listed. It does not replace a consultation with a doctor; in an emergency call 112. If you spot an inaccuracy, write to [email protected].