Your thyroid is a small, butterfly-shaped gland in your neck, but it has an outsized effect on how you feel. It controls your metabolism, the rate at which your body uses energy. When it makes too little or too much hormone, the effects ripple through your entire body, often in ways people mistake for stress, ageing, or simply feeling run-down. This guide explains the two main thyroid problems and how to recognize them.
What the thyroid does
The thyroid releases hormones that regulate metabolism, body temperature, heart rate, and energy levels. The brain monitors these hormones and adjusts production using a signal called TSH (thyroid-stimulating hormone). This is why a TSH blood test is usually the first step in checking thyroid function.
Underactive thyroid (hypothyroidism)
When the thyroid is underactive, everything slows down. This is the more common thyroid problem.
- Tiredness and low energy
- Weight gain despite no change in diet
- Feeling cold easily
- Dry skin and hair
- Constipation
- Low mood or brain fog
- Heavier or irregular periods
Overactive thyroid (hyperthyroidism)
When the thyroid is overactive, the body speeds up.
- Unexplained weight loss
- Rapid or irregular heartbeat
- Feeling anxious, irritable, or restless
- Shaking or tremor in the hands
- Feeling hot and sweating more
- Difficulty sleeping
- More frequent bowel movements
Easy to overlook
Thyroid symptoms are often vague and develop gradually, so they are frequently blamed on stress or busy lives. If a cluster of these symptoms sounds familiar, a simple blood test can clarify what is going on.
Who is more likely to be affected
Thyroid problems are more common in women, become more likely with age, and can run in families. They are also more common in people with other autoimmune conditions and can appear during or after pregnancy. Hashimoto's and Graves' disease are common autoimmune causes.
Diagnosis and management
Diagnosis usually starts with a TSH test, sometimes with additional thyroid hormone tests and antibody checks. Treatment depends on the type and cause. Many thyroid conditions are very manageable once identified, often with ongoing monitoring to keep hormone levels balanced.
Treatment is highly individual
Thyroid hormone replacement and other treatments must be carefully dosed and monitored by a licensed doctor through repeat blood tests. Too much or too little can cause problems, so never self-adjust thyroid medication or buy it without medical guidance.
Rare but serious
Severe untreated thyroid disease can occasionally cause a crisis. Seek emergency care for a very rapid or irregular heartbeat with chest pain, high fever with confusion, or extreme drowsiness. Call 911 (US/CA), 999 (UK), or 112 (EU).
Get checked, feel like yourself again
Thyroid symptoms are easy to dismiss but worth investigating, because effective treatment can transform how you feel. A verified doctor on iHealix can review your symptoms, arrange thyroid blood tests, and explain what your results mean and what to do next.