Thyroid hormone balance: symptoms, tests and GP guidance
The thyroid gland plays an important role in regulating metabolism, energy levels, body temperature and many other body functions. Thyroid hormone imbalance is common and can cause a wide range of symptoms, but those symptoms are often non-specific and overlap with many other conditions.
This page explains how GPs assess thyroid hormone balance, when blood tests are useful, what common results mean, and when treatment or further investigation is considered.
These articles are intended as educational sources, not diagnostic nor taking place of a proper medical assessment. If you need help, please book an appointment with one of our GP’s.
What the thyroid gland does
The thyroid is a small gland in the neck that produces thyroid hormones, mainly thyroxine (T4) and triiodothyronine (T3). These hormones influence how quickly the body uses energy and affect many organs, including the heart, brain, muscles and digestive system.
Thyroid hormone production is regulated by thyroid-stimulating hormone (TSH), which is released by the pituitary gland. Most thyroid assessments focus on this feedback system.
Common symptoms linked to thyroid imbalance
Thyroid symptoms can be subtle and develop gradually. They may also be caused by non-thyroid conditions, which is why testing is interpreted carefully.
Symptoms sometimes linked to an underactive thyroid
- Tiredness or low energy
- Weight gain
- Feeling cold
- Dry skin or hair thinning
- Constipation
- Low mood or slowed thinking
- Heavy or irregular periods
Symptoms sometimes linked to an overactive thyroid
- Weight loss
- Heat intolerance
- Palpitations or fast heart rate
- Anxiety or tremor
- Increased sweating
- Diarrhoea
- Irregular periods
Symptoms alone are not enough to diagnose a thyroid condition.
How GPs assess thyroid hormone balance
Assessment usually starts with:
- A detailed symptom history
- Review of medications and medical history
- Examination where appropriate
Blood tests are used to confirm or exclude thyroid disease and are interpreted alongside symptoms.
Thyroid blood tests explained
TSH (thyroid-stimulating hormone)
TSH is usually the first test checked. It reflects how hard the pituitary gland is working to stimulate the thyroid.
- High TSH may suggest an underactive thyroid
- Low TSH may suggest an overactive thyroid
Free T4
Free T4 helps confirm whether thyroid hormone levels are low or high and supports interpretation of TSH results.
Free T3
Free T3 is not always required. It may be checked in specific situations, particularly if overactive thyroid is suspected.
Thyroid antibodies
Antibody tests may be used if autoimmune thyroid disease is suspected, such as Hashimoto’s thyroiditis or Graves’ disease.
Testing is guided by clinical context.
Common thyroid conditions seen in primary care
Hypothyroidism (underactive thyroid)
This occurs when the thyroid does not produce enough hormone. It is commonly caused by autoimmune thyroid disease.
Treatment is usually straightforward and involves thyroid hormone replacement when clinically indicated.
Hyperthyroidism (overactive thyroid)
This occurs when the thyroid produces too much hormone. Causes include Graves’ disease and thyroid nodules.
Management depends on severity and often involves specialist input.
Subclinical thyroid dysfunction
Some people have abnormal TSH levels but normal thyroid hormone levels and minimal or no symptoms.
In many cases, monitoring rather than immediate treatment is recommended.
Why symptoms do not always match blood test results
Thyroid symptoms overlap with many other conditions, including:
- Iron deficiency
- Vitamin deficiencies
- Sleep problems
- Stress and anxiety
- Perimenopause and menopause
- Depression
A normal thyroid blood test usually means symptoms are unlikely to be caused by thyroid disease alone.
When treatment is usually considered
Treatment decisions are based on:
- Blood test results
- Severity and persistence of symptoms
- Age and cardiovascular risk
- Pregnancy or fertility considerations
GPs avoid starting treatment based on symptoms alone when blood tests are normal.
Monitoring and follow-up
If a thyroid condition is diagnosed, follow-up may involve:
- Repeat blood tests after dose changes
- Monitoring symptoms and side effects
- Long-term review in stable cases
Many people with thyroid conditions are managed safely and effectively in primary care.
When to seek GP review
Consider GP review if:
- You have persistent symptoms suggestive of thyroid imbalance
- You have abnormal thyroid blood tests
- You are on thyroid medication and symptoms change
- You are planning pregnancy or are pregnant
- You want help interpreting thyroid test results
Further Reading and Hub Links
Visit our Hormone Health hub or browse more health topics in the AccessGP Knowledge Base.
If you have concerns about thyroid symptoms or blood test results, a GP can assess your situation and advise on appropriate investigation or follow-up.
Last reviewed by Dr Zamiel Hussain, GMC registered GP
Updated: 31 December 2025