An underactive thyroid: symptoms that are easy to miss
Fatigue, cold, weight gain, slow thinking
Dr. Karim Nasri
Endocrinologist
In simple terms
Why hypothyroidism is often mistaken for stress or ageing, and how it is confirmed.
What the thyroid does
This small gland at the base of the neck sets the pace of metabolism in nearly every tissue. When it produces too little hormone, everything slows down.
Typical symptoms
- Persistent fatigue and needing more sleep
- Feeling cold when others are comfortable
- Weight gain of a few kilos despite no change in eating
- Dry skin, brittle hair, constipation
- Low mood, slower thinking and memory
- Heavier or irregular periods
How it is diagnosed
A blood test measuring TSH is the first step. A raised TSH with a low free T4 confirms hypothyroidism. Antibody testing can show whether the cause is Hashimoto's thyroiditis, the most common reason in adults.
Treatment
Daily levothyroxine, a synthetic version of the missing hormone, taken on an empty stomach and separated from calcium, iron and coffee by at least half an hour. Doses are adjusted from blood tests every 6 to 8 weeks until stable, then checked yearly.
Living with it
Treated properly, life expectancy and energy return to normal. Do not stop the tablet when you feel better: the gland has not recovered, the hormone is simply being replaced.
The words explained
Medical terms used above, in everyday language.
- Symptom
- A sign you can feel or see that something is wrong, like pain, tiredness or a rash.
- Diagnosis
- The moment a doctor identifies which illness is causing your symptoms.
- Hormone
- A chemical messenger made by your body that tells organs what to do.
- Metabolism
- How your body turns food into energy and builds or repairs itself.
- Antibody
- A protein your body makes to recognise and neutralise a specific germ.
When should you see a doctor?
- Your symptoms last more than a few weeks or keep coming back.
- They get worse quickly, or stop you doing everyday things.
- You notice sudden pain, breathing trouble, fainting or bleeding — seek urgent care.
- You already take medication and want to change anything about it.
This article explains general health information. It does not replace advice from your own doctor.
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