Overactive thyroid (hyperthyroidism)
In hyperthyroidism the thyroid gland pours more hormone into the blood than the body needs, and the metabolism speeds up.
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Medicines commonly prescribed for Overactive thyroid (hyperthyroidism)
For informational purposes only. Always consult a doctor before using any medicine.
Dosage form: TABLET, 40 mgActive substance: propranololManufacturer: Tarbis Farma S.L.Prescription requiredDosage form: TABLET, 10 mgActive substance: propranololManufacturer: Aurovitas Spain, S.A.U.Prescription requiredDosage form: TABLET, 5 mgActive substance: carbimazoleManufacturer: Ferrer Internacional S.A.Prescription required
In hyperthyroidism the thyroid gland pours more hormone into the blood than the body needs, and the metabolism speeds up. People lose weight while eating more than usual, cope badly with heat, feel the heart racing and notice their hands shaking. It is considerably more common in women and usually starts between twenty and forty, though it can appear at any age. It responds well to treatment but does not settle on its own, and left alone it wears out the heart and the bones year after year.
What changes in the body when there is too much hormone
The thyroid sits at the front of the neck, wrapped around the windpipe. It makes two hormones, thyroxine (T4) and triiodothyronine (T3), which set the pace at which every tissue works: how fast the heart beats, how much heat the body gives off, how energy is spent, how briskly the bowel moves.
The gland takes its orders from the pituitary, a small structure at the base of the brain. It releases thyroid-stimulating hormone (TSH), and the more of it there is, the harder the thyroid works. The feedback is strict: as soon as hormone levels in the blood climb, the pituitary shuts TSH off almost completely. That is why in hyperthyroidism the blood test shows a low TSH with a high T4 or T3, and it is this combination that gives the diagnosis away.
The signs that give it away
Symptoms build over months and are commonly put down to stress or tiredness. Hyperthyroidism is worth suspecting when several of these coincide:
- nervousness, anxiety, short temper, swings of mood;
- trouble falling asleep and light, broken sleep;
- trembling fingers, obvious with the arms held out;
- a fast or irregular heartbeat, a sense of the heart missing beats;
- poor tolerance of heat, sweating, warm moist skin;
- weight loss with a normal or even increased appetite;
- weak thigh muscles — stairs are hard work and it is difficult to get out of a low chair;
- frequent loose stools;
- in women, scanty or infrequent periods and difficulty conceiving;
- in men, a drop in sex drive.
Swelling in the neck (a goitre) does not appear in everyone, and on its own it says nothing about hormone levels: an enlarged gland may work normally or even under-work. In older people the picture can be deceptively quiet — apathy and weakness instead of agitation, with a newly discovered irregular heartbeat or unexplained weight loss as the only clue.
Why the gland starts overworking
The cause matters, because the choice of treatment follows from it.
- Graves' disease — an autoimmune condition and the commonest cause. The immune system makes antibodies that latch on to the TSH receptor and drive the gland, bypassing the pituitary altogether. The tendency runs in families, and smoking both raises the risk and markedly worsens the eye involvement.
- Thyroid nodules. One nodule or several begin producing hormone on their own account, taking no notice of the pituitary. This is seen mainly in later life and in areas where the diet is short of iodine.
- Thyroiditis — inflammation of the gland. Tissue is damaged and the stored hormone spills into the blood at once. The excess here is temporary: a phase of underactivity usually follows, and then recovery. It happens after a viral infection, when the neck is tender, and in the first months after childbirth.
- Iodine and medicines. A large dose of iodine — from contrast used in scanning, from antiseptics, from drugs given for irregular heart rhythms — can unsettle the gland. So can too much replacement hormone taken for an underactive thyroid, and slimming or "energy" supplements, which sometimes contain thyroid extract.
- Rare causes: an excess of the pregnancy hormone hCG, especially in a multiple pregnancy, and a pituitary tumour producing TSH.
Which tests confirm it
The starting point is a blood test: TSH, free T4 and free T3. A low TSH with a raised T4 or T3 confirms hyperthyroidism. If the TSH is low while the hormones sit within range, the picture is subclinical — still worth watching, because it too takes a toll on the heart and the bones.
Next comes the cause, and for that a single blood test is not enough.
- Antibodies against the TSH receptor. Finding them all but confirms Graves' disease and saves further searching.
- A radioisotope scan, which uses a small amount of a radioactive tracer to show how eagerly the gland takes it up. In Graves' disease uptake is raised evenly throughout the gland; with a toxic nodule only the nodule lights up; in thyroiditis, and where the hormone has been taken by mouth, there is almost no uptake at all. That distinction is decisive: thyroiditis is not treated with drugs that block hormone production, because they achieve nothing there.
- Ultrasound assesses the size of the gland, the texture of the tissue and any nodules, but says nothing about how much hormone is being made. The diagnosis is never made on a scan alone.
The pulse and an ECG are checked at the same time: atrial fibrillation is often the first thing found.
How it is treated
There are three routes, and the choice depends on the cause, your age, the size of the gland, plans for pregnancy and the state of the eyes. It is worth deciding with an endocrinologist.
Antithyroid tablets. These block the assembly of hormone inside the gland. The effect takes several weeks to show and the course runs for more than a year. In some people stopping the tablets is followed by lasting remission; in others the illness returns, and then the more definitive options are discussed.
Beta blockers. They do nothing to the gland itself but within days take away the palpitations, the tremor and the restlessness while the main treatment gathers pace.
Radioactive iodine. A drink or a capsule is taken, the isotope collects in the gland and gradually switches off the overactive tissue. One dose is usually enough, and the effect unfolds over weeks or months. It is not used in pregnancy or while breastfeeding, and is used cautiously where the eyes are badly affected. For a few days afterwards close contact with young children and pregnant women is limited, and conceiving is postponed for some months; the exact intervals are set by the centre giving the treatment.
Surgery. Removing the gland is offered for a large goitre pressing on the windpipe or gullet, where a nodule is suspicious for cancer, in severe eye disease, and when tablets have failed.
After radioactive iodine and after surgery the gland can no longer keep up and an underactive thyroid follows. This is not a complication but the expected outcome: it is made good with a daily thyroid hormone tablet, lifelong but with ordinary health.
What to agree with your doctor for the treatment period
Antithyroid tablets have side effects that are best known about in advance.
The most serious is a sudden fall in the white cell count. It is uncommon but comes on abruptly and leaves a person defenceless against infection. The rule is simple: with a high temperature, a sore throat or mouth ulcers, stop the tablets at once and have a full blood count the same day. Waiting for the next scheduled appointment is not an option.
Another reason to seek help urgently is yellowing of the skin and the whites of the eyes, dark urine, pale stools, intense itching or pain under the right ribs: that is how liver damage announces itself.
The commoner and less dangerous complaints — a rash, itching, nausea, joint pain, an altered sense of taste — usually settle on their own or simply call for a change of tablet.
Discuss pregnancy separately. Some antithyroid drugs are best avoided in the first three months, so reliable contraception is needed during treatment and any plan to conceive should be raised in advance: the regimen is changed before pregnancy, not after it. Poorly controlled hyperthyroidism in pregnancy raises the risk of pre-eclampsia, premature birth, miscarriage and low birth weight, so treatment is adjusted rather than abandoned.
The eyes in Graves' disease
About one person in four with Graves' disease develops eye trouble: the same antibodies act on the fat and muscles of the eye socket, the tissues swell and push the eyeball forward. It is a separate strand of the illness and does not always settle when the hormone levels do.
The first signs are grittiness and dryness, discomfort in bright light, watering, swollen red eyelids and a feeling of pressure behind the eye. Later the eyes may protrude, the lids no longer close fully and double vision appears on looking to the side.
Do not put off seeing an eye specialist if double vision becomes constant, if the eye is red and painful and above all if sight becomes blurred or colours look washed out: that is pressure on the optic nerve, and treatment for it starts straight away. Lubricating drops, shelter from wind and glare and raising the head of the bed all help. But the single most effective thing within your own control is stopping smoking: nothing else worsens the eye disease as much.
What untreated hyperthyroidism leads to
Years of excess hormone overload the heart and strip the bones. Hence the main complications:
- atrial fibrillation — an irregular, often fast rhythm that raises the risk of stroke;
- heart failure in those whose heart is already damaged;
- osteoporosis: calcium leaves the bone and it begins to break under modest loads.
The most feared complication is a thyroid storm. It is rare, arising on top of undiagnosed disease or after someone has stopped their tablets unilaterally, and it is set off by infection, injury, an operation or childbirth.
Call an ambulance — in Spain, Italy, Portugal, Poland and Ukraine the single European number is 112 — if someone with hyperthyroidism has:
- a temperature climbing sharply above 39 °C;
- a fast, irregular pulse with breathlessness;
- vomiting or profuse diarrhoea with rapid dehydration;
- severe agitation, confusion, delirium or, conversely, deep drowsiness;
- yellowing of the skin.
While waiting for the ambulance, lay the person down, cool them and give fluids if they are conscious and not vomiting.
Online consultation
Much of the medical work in hyperthyroidism comes down to reading blood tests and tuning the dose, and that is easily done remotely. In an online consultation an endocrinologist explains what your TSH, T4 and T3 figures mean, which tests are still missing before the cause can be pinned down, and how often to repeat the bloods while on treatment.
Have ready every thyroid result from past years — the trend matters more than any single value — along with ultrasound and isotope scan reports, a list of medicines and supplements with doses, and a note of your pulse and weight. Say explicitly if you have had a contrast scan or take drugs for an irregular heart rhythm: both change how the results are read.
Results can be interpreted remotely, the choice between tablets, radioactive iodine and surgery talked through, and a pregnancy planned. But where a thyroid storm is suspected, where a new irregular heartbeat comes with breathlessness and chest pain, or where vision is deteriorating quickly, an online appointment is the wrong tool: that needs face-to-face care without delay.
This material is for information only and does not replace medical advice.
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