WHEN YOUR THYROID PILLS DON’T WORK

SYMPTOMS of an underactive thyroid, such as weight gain and fatigue, don’t always improve on levothyroxine — a synthetic version of the natural thyroxine hormone, T4 — even when blood tests suggest hormone levels have returned to normal.

For some, this may be because their condition is borderline and perhaps they don’t need to be on levothyroxine in the first place, says consultant endocrinologist Dr Salman Razvi.

However, another explanation is that they may also need supplementary T3 — the other hormone produced by the thyroid. Normally, T4 accounts for 75 per cent of the hormones produced by the thyroid gland, T3 the other 25 per cent. The body then converts T4 into the more active T3 as required.

‘We think some people might not be able to convert T4 into T3 as well,’ says consultant endocrinologist Dr Peter Taylor.

‘In clinic we find that a third of people don’t notice any difference on T3 as well as T4, a third feel a bit better and a third feel much better,’ adds Dr Taylor, who believes it’s worth considering T3 treatment if someone doesn’t see improvement on T4 alone. But research on T3’s long-term safety combined with T4 is still in its early stages.

And, as Dr Taylor acknowledges, ‘if you’re not feeling right on T4, it may have another cause aside from the thyroid — and it can be quite hard to find a doctor who will keep an eye on your T3 on the NHS’.

There have also been supply issues for T3, with many NHS commissioning bodies restricting its use after manufacturers hiked up the price by 4,600 per cent, as previously reported by Good Health.