Hypothyroidism

Also called Underactive thyroid

A thyroid making too little hormone. Common, cheap to treat, and constantly mistaken for something else.

What it is

The thyroid sets the body's metabolic pace. When it slows, everything does: heart rate, digestion, thinking, mood, temperature.

It affects around 2% of the UK population, mostly women, and the risk rises with age. In Down's syndrome it is far commoner still, which is why annual thyroid testing is part of good practice there.

The symptoms are the reason it gets missed. Tiredness, weight gain, low mood and slowed thinking are attributed to age, to depression, to a learning disability, or to a hundred other things.

Signs you might notice

Fatigue. Weight gain without change in eating. Feeling the cold.

Dry skin, thinning hair, brittle nails.

Constipation. Heavy or irregular periods.

Low mood and slowed thinking, which is frequently treated as depression alone.

In older people it can present mainly as confusion or as heart failure getting worse.

How it can affect day-to-day life

The diagnostic overshadowing problem is acute here. In somebody with a learning disability or dementia, "slower than they used to be" gets recorded as progression rather than tested. A blood test costing a few pounds is the difference.

Treatment is a single daily tablet, levothyroxine, and it works well. But absorption is fussy: calcium, iron, some indigestion remedies and soya all block it.

Doses need review after any significant weight change, in pregnancy, and periodically in older age.

Supporting someone well

Take levothyroxine on an empty stomach, at least 30 minutes before food, and keep at least four hours between it and calcium or iron.

Take it at the same time every day. Bedtime works well if mornings are chaotic, provided it is well after eating.

Get the blood test done before the morning dose, not after, or the result misleads.

For anybody with Down's syndrome, ask for a thyroid test annually and treat any slowing down as a reason to check rather than a reason to lower expectations.

Do not adjust the dose based on how you feel without a blood test. Too much thyroid hormone causes atrial fibrillation and bone loss.

Where to get help

A GP diagnoses and monitors this with a TSH blood test.

British Thyroid Foundation have clear patient information, including on the persistent debates about combination treatment.

Severe hypothyroidism with confusion, low temperature and drowsiness is a medical emergency.