Hypothyroidism: symptoms, blood tests and when to see a doctor
Tiredness, feeling the cold more often or dry skin can have many explanations. Blood tests, not symptoms, show whether the thyroid is making too little hormone.
Hypothyroidism can cause tiredness, feeling cold, weight gain, constipation, dry skin or low mood, but these symptoms are not specific. Other health problems can cause them too, and some people with abnormal results have no typical symptoms. The diagnosis is confirmed with blood tests: TSH and free thyroxine (FT4), interpreted by a doctor together with your history and an examination. If you recognise several of these signs, or they persist, talk to a doctor before drawing any conclusions.
What you may notice
What symptoms hypothyroidism can cause
When the thyroid makes too little hormone, the changes usually come on gradually and are easy to put down to other causes.
- marked tiredness and feeling cold more often than before;
- weight gain and constipation;
- difficulty concentrating, forgetfulness, low mood;
- dry skin, dry hair or hair loss, a hoarse voice;
- in women, irregular or heavy periods.
In older people the picture can be different: weight loss, confusion, reduced appetite, stiff joints or weakness. These signs can be mistaken for dementia or depression, which is why they are worth discussing with a doctor.
Sources: NHS, hypothyroidism; MSD Manual, hypothyroidism.
Symptoms are not enough
Why symptoms cannot confirm the diagnosis
Not everyone has every symptom, and the same symptoms can also be caused by other health problems.
Tiredness or weight gain can have many explanations besides the thyroid. Conversely, in mild forms few people have typical symptoms, even though tests show slightly altered thyroid function. An online test or a symptom checklist therefore cannot tell whether you have hypothyroidism.
The most common cause is an autoimmune disease, Hashimoto's thyroiditis, in which the immune system attacks the thyroid. Hypothyroidism can also develop after thyroid surgery or radiotherapy, or be caused by iodine deficiency or certain medicines.
Sources: American Thyroid Association, hypothyroidism; ETA 2013 guideline on subclinical hypothyroidism; NHS, causes.
TSH and FT4
Which blood tests confirm hypothyroidism
The basic tests are TSH, the hormone that stimulates the thyroid, and free thyroxine (FT4), the form of the hormone the body can use.
When the thyroid does not make enough hormone, TSH rises. FT4 shows how much thyroid hormone is available in the blood. The doctor interprets the two values together and may examine your neck to see whether the thyroid is enlarged.
If TSH is raised but FT4 is within the reference range, this is called subclinical hypothyroidism. The European Thyroid Association guideline recommends repeating TSH and FT4, together with thyroid peroxidase antibodies (anti-TPO), preferably after 2–3 months. A temporary rise in TSH can occur, for example, while recovering from a serious illness, during thyroid inflammation or during certain treatments.
Sources: American Thyroid Association; ETA 2013 guideline.
Timely assessment
When it is worth seeing a doctor
Book an appointment if you think you might have hypothyroidism, especially when symptoms persist or add up.
Your GP can arrange the tests and, if needed, refer you to an endocrinologist. Bring a list of your medicines and supplements, any previous results and a note on how your symptoms have changed over time.
Sources: NHS, when to get help and myxoedema coma; MSD Manual, myxoedema coma.
After the diagnosis
What happens once the diagnosis is confirmed
The usual treatment replaces the missing thyroid hormone. The medicine is prescribed, dosed and monitored by a doctor.
Treatment is usually long term, sometimes lifelong, so that symptoms do not come back. The doctor checks your blood tests 6–8 weeks after starting treatment or after each dose change, then at regular intervals. Do not change or stop the treatment on your own.
Thyroid hormones must not be used for weight loss: if your levels are normal, they do not reduce body weight. An online consultation for chronic conditions can cover your history, a discussion of your results and the follow-up plan; the blood sample itself is taken at a laboratory.
Sources: NHS, treatment; American Thyroid Association, monitoring.
Next steps
Talk to a doctor about your symptoms and tests
The doctor decides which tests are needed, interprets the results and judges whether you need treatment or an endocrinologist.
- Online consultation for chronic conditions
- Doctors available in Romania
- Contact
- Chronic conditions and national health programmes
Have your results and questions ready
Bring your recent test results, a list of your medicines and supplements and a description of your symptoms. The doctor decides the next steps.
Evidence
Medical sources
Sources checked on 5 October 2026.
This article describes possible symptoms, confirmatory tests and next steps; it does not give treatment thresholds, doses or treatment regimens. National health programmes are not covered here.
Questions
Frequently asked questions about hypothyroidism
Can I tell from my symptoms whether I have hypothyroidism?
No. The symptoms are non-specific and can have other causes. The diagnosis is confirmed with blood tests, TSH and FT4, interpreted by a doctor.
Does a slightly raised TSH mean I need to start treatment?
Not necessarily. A raised TSH with a normal FT4 is usually repeated after a few months, because the values can return to normal. The doctor decides whether and when treatment is needed.
How often are tests repeated after starting treatment?
Usually 6–8 weeks after starting treatment or after a dose change, then at regular intervals, as advised by your doctor.
