Thyroid Imbalance: Early Warning Signs to Watch For

10 Nov 2025

Your thyroid may be small, but its impact is significant. It is situated in the front of the neck, located just below the Adam's apple, spanning across in a butterfly shape. Your thyroid gland secretes hormones that regulate energy, metabolism, body temperature, heart rate, digestion, and many other bodily functions. It frequently has wide-ranging effects on health when the output from the thyroid gets too high (overactive thyroid), or too low (underactive thyroid).

This blog explains how thyroid imbalance can present itself early and what subtle signs to look for, what tests may be required, and what to do and when to do it, with emphasis on the UK population and current practice.

If you are simply browsing for your health or to look for screening options at a private clinic in London, recognising the early signs of possible thyroid imbalance can make an actual difference.

Understanding the Thyroid: What it Does & Why is it Important

The thyroid gland secretes two key hormones –triiodothyronine (T3) and thyroxine (T4), which influence almost every cell in your body by regulating how quickly your body conducts metabolism - converts fuel into energy. In turn, the pituitary gland releases thyroid stimulating hormone (TSH) to gauge the body’s needs. When the thyroid is unable to produce adequate hormones, TSH rises to push it harder to work; vice versa when the thyroid is overactive, TSH drops.

When hormones are out of balance, symptoms may be mild in nature. This is often why individuals may choose to disregard symptoms or simply blame them on ‘getting older’.  However, early symptoms recognition and treatment can help avoid complications and restore quality of life. In the UK, guidelines highlight that thyroid disorders are common, and appropriate testing and follow-up are crucial.

Underactive Thyroid (Hypothyroidism): The Slow-Down Mode

What is it?

Hypothyroidism is the condition where your thyroid gland does not produce enough hormone, and your body processes start to slow down. According to UK data, hypothyroidism affects around 15 in every 1,000 women and about 1 in every 1,000 men.

Signs to Watch Out For

These symptoms usually build up over time and may be unnoticeable at first:

• Mild fatigue or lethargy despite adequate sleep.
• Modest weight gain at first, even if diet or exercise have not changed.
• Feeling unusually cold or more sensitive to outside chills or cold rooms.
• Rough, dry or flaky skin; brittle nails; hair thinning or hair loss.
• Constipation or slowed digestion.
• Slow heart rate (bradycardia) or mild swelling (puffiness) of the face or eyelids.
• Mood changes –depression or low mood, poor concentration, ‘brain fog’.
• Heavy, irregular or prolonged menstrual periods in women; low libido in both sexes.

As these symptoms overlap with many other conditions (e.g., depression, anaemia, menopause or just ageing), thyroid imbalance is often not recognised for several months or even years.

Why this happens

Common causes in the UK are:

• Autoimmune thyroiditis (Hashimoto’s thyroiditis) – a condition where the immune system attacks the thyroid.
• Past treatment for an overactive thyroid, thyroid surgery or radio-iodine.
• Certain medications may influence thyroid function.
• Although rare in the UK, iodine deficiency.

When to ask for help

Please see your GP or a private specialist if you have several of the symptoms listed above, especially if you are a woman aged 30 or older (due to higher risk) or have any family history of thyroid disease.

Overactive Thyroid (Hyperthyroidism): The Fast-Forward Mode

What is it?

Hyperthyroidism occurs when the thyroid is producing excessive hormone and everything in the body speeds up. The guidelines from the UK state that females are ten times more prone to this condition as compared to males, and it usually occurs between the ages of 20 to 40.

Typical Early Symptoms

Here are some early warning signs to look for:

• Feeling anxious, nervous, restless, shaky, or feeling jittery for no reason.
• Feeling hot even in a comfortable atmosphere, sweating excessively or being intolerant to heat.
• Losing weight even with increased appetite.
• Elevated heart rate or heart palpitations, with irregular heart rate in more advanced cases.
• Difficulty sleeping or feel tired despite sleeping less.
• Frequent bowel movements or diarrhoea, or more thirsty and urinating more often.
• Swelling at the base of your neck (goitre) or feeling a “lump” in your throat.
• Fewer or lighter periods in females, and lower libido in males.

Some of the symptoms may feel similar to anxiety or menopause, or just high stress;so the chances of overactive thyroid is not always obvious. Further, if you are experiencing these symptoms, especially collectively, thyroid function should be assessed.

Importance of Early Indicators: The Spectrum of Diagnosis and Management

• Overlap and subtleties: Many symptoms (such as mood changes, weight gain or loss, and tiredness) are non-specific and may be misinterpreted – having the ability to recognise familiar signals and establish patterns is of utmost importance.
• Avoiding downstream complications: Lack of treatment for thyroid dysfunction (hypo or hyper) may result in significant complications, such as fertility issues, altered cholesterol levels, cardiovascular disease, and in rare cases increased risk to life.
• Quality of life: Even modest hormone imbalances within the thyroid can impact cognition, mood, libido, pregnancy outcomes, energy, or activities of daily living. Early recognition promotes wellbeing.
• Better outcomes with treatment: For example, in case of hypothyroid, hormone replacement therapy is usually effective once the provider has arrived at the correct dosage. When hyperthyroid, early referral enables early course of treatment to control the imbalance with the thyroid dysfunction.

How are Thyroid Disorders Diagnosed in the UK?

In line with the latest UK guidance, once thyroid dysfunction has been suspected, evaluation will follow a pathway.

Initial Blood Testing

There are some tests to be done:

• TSH (thyroid stimulating hormone)
• Free T4 (free thyroxine)
• Free T3 could also be considered (specifically in some cases of hyperthyroid)

In terms of interpretation:

• Hypothyroid will present as increased TSH with low T4.
• Hyperthyroidism will present as low TSH with elevated T4 (and/or T3).

Further Investigations (if necessary)

• Assessment for anti-thyroid antibodies (like in the context of Graves’ disease or Hashimoto’s).
• Ultrasound or scan of the thyroid (to rule out structural abnormalities such as goitreornodules).
• Further specialised tests if pituitary or secondary thyroid disease is suspected.

Referrals and Specialist Care

Where complications arise, pregnancy, children or abnormal presentation are involved, NHS guidelines provide referral to an endocrinologist.

Monitoring and Review

Once treatment begins, blood tests for routine monitoring will enable clinicians to ensure that hormones levels have been optimised and that symptoms have resolved.

Who is at risk? Should you be screened?

Risk Factors for Thyroid Imbalance

• Women have a significantly higher chance of developing thyroid disorders.
• Family history of thyroid disease.
• History of thyroid surgery, radio-iodine treatment, or treatment for overactive thyroid.
• Autoimmune conditions (such as type 1 diabetes, vitiligo).
• Pregnancy or planning pregnancy, as thyroid disease may affect fertility and foetal development.
• Thyroid disease may often be underappreciated as a normal process of ageing, but isactually a treatable cause of symptoms.
• Unexplained high cholesterol, hair thinning, persistent or recurrent constipation, other features of thyroid disease.

When is it right to consider screening?

In a private setting (such as a well-man health check or full body MOT), the introduction of a thyroid function test may be appropriate if symptoms or risk factors are present. Even if asymptomatic, individuals with risk factors like former thyroid treatment, family history, or pregnancy, may wish to have baseline TSH/T4 screening undertaken.

However, in the absence of a symptom, routine universal screening of adults is not generally recommended by UK guidelines.

What You Can Do Now – A Practical Guide to Clients/Patients

Self-Check Your Symptoms

Make a note if you have experienced two or more of the following:

• Unexplained tiredness, change in weight, sensitivity to heat or cold
• Brittle nails, dry skin, or hair loss
• Mood swings, difficulty concentrating, lapses of memory
• Palpitations, swollen neck, changes in bowel habits, tremour

You could mention a thyroid check with your clinician if these persist for more than a few weeks, and no obvious other reason can be identified.

Lifestyle Changes

While lifestyle alone cannot cure thyroid disease, optimising overall wellbeing will improve your general health as well as your thyroid function. This should include:

• A balanced diet of nutrients – iodine intake is usually adequate in the UK, but avoid extremes
• Regular physical activity to improve metabolic health
• Control stress and adequate sleep – as thyroid symptoms can aggravate fatigue or stress cycles
• If you are on thyroid medication, you should take it first thing in the morning on an empty stomach and separate from calcium or iron supplements

The Role of Private Clinics and Referrals

In a private medical & dental clinic (in South Kensington), you may be able to get:

• Thyroid function screening as part of a wider blood panel (like in Well Man/Woman check).
• Clear guidance and advice on when to refer to endocrinology.
• Help interpreting mild symptoms and results, particularly where standard testing appears ‘normal’, yet symptoms remain.

When to Act Urgently

Although thyroid problems typically develop gradually and GP review can often be scheduled routinely, there are times where more urgency is needed for assessment, such as:

• If you have a new rapid heart rate, breathlessness, or chest pain – this may suggest severe over-active thyroid (thyroid storm) or cardiac complication.
• If you have a large goitre that is causing problems with breathing or swallowing.
• Pregnancy or planning for pregnancy – untreated thyroid disease poses risk to mother and foetus (e.g. miscarriage, pre-eclampsia, growth issues).
• Symptoms of pituitary disease or thyroid cancer (in rare cases) – such as extreme neck swelling, very acute change, hoarseness.

In these circumstances, a GP referral is necessary, rather than waiting for a screening to address.

Summary: What Should You Not Miss

• Although the thyroid gland is small, the impact of imbalance can be wide-ranging.
• Underactive (hypothyroid) commonly slows down body functions, leading to fatigue (often with insignificant tasks), cold intolerance, weight gain, mood swings, and skin becomes dry and itchy.
• Overactive (hyperthyroid) commonly speeds things up, resulting in weight loss, anxiousness, palpitations, heat intolerance, and increased bowel frequency.
• No time lost with early recognition! Symptoms are often vague and therefore missed; treatment of thyroid disease can restore quality of life and prevent chronic long-term complications.
• In UK, diagnosis is obtained via a full and accurate thyroid function blood test (TSH + free T4). Additional investigations can be provided if required, if abnormal thyroid function is confirmed.
• Risk factors include family history, female sex, history of autoimmune disease, former treatments related to thyroid, and pregnancy.
• Lifestyle habits including exercise, a healthy diet, sleep and stress management support thyroid health. However, there’s no replacement of medical treatment where necessary.
• For clinics, the provision of screening, interpreting or reporting of results with full context, and referring timely are the key services.

If you have noticed some ongoing symptoms like changes in weight, unexplained fatigue, changes in mood, or a feeling of a lump at the bottom of your neck, it may be time to schedule a thyroid function test. Based in South Kensington, our clinic offers male and women’s health and full body MOT packages that consist of thyroid testing, hormone panels and interpretation.