Thyroiditis: symptoms, types and treatment

The symptoms depend on what the thyroid hormone level is doing, not on the name of the thyroiditis. In an overactive phase, the NHS lists nervousness, anxiety, irritability, trouble sleeping, heat sensitivity, palpitations, tremor and weight loss. In an underactive phase the NHS lists tiredness, feeling cold, weight gain, constipation, low mood, dry skin and a croaky voice.

Pain at the front of the neck, tenderness when touched and a recent flu-like illness point towards the sub-acute type. A painless swelling with gradually developing tiredness points towards the autoimmune type.

• Overactive phase: palpitations, tremor, anxiety, heat sensitivity

• Underactive phase: tiredness, cold intolerance, constipation, low mood

• Painful, tender neck swelling after a viral illness (sub-acute)

• Painless swelling with slowly worsening tiredness (autoimmune)

• New symptoms in the months after childbirth (postpartum)

Treatment depends on the type and on what the thyroid hormone level is doing. The British Thyroid Foundation advises a thorough evaluation by an endocrinologist to determine which type you have, because this may save unnecessary treatment: many types need none.

The NHS says an underactive thyroid is usually treated with levothyroxine tablets to replace the hormone your body cannot produce, with regular blood tests to check you are on the right dose, and that for an overactive thyroid the main treatments are medicine that stops your thyroid making too much hormone, radioiodine and surgery. In thyroiditis, many people need only short-term or symptom treatment, as the table shows.

Thyroiditis is a general name for an inflamed thyroid. It is not one illness. The cause, the symptoms and the outlook differ between types, which is why the British Thyroid Foundation advises a thorough evaluation by an endocrinologist to determine which type you have. This may save unnecessary treatment, as many types need none.

Inflammation damages thyroid cells and can release stored hormone into the blood, causing a spell of overactivity. Later, once the stores run low, the gland may be underactive. In some types the gland recovers, in others it does not.

This type is believed to be caused by a viral infection of the gland, usually with flu-like symptoms. The BTF says it is more common in women than men and most often affects people aged 20 to 50. The main feature is usually an enlarged, painful or tender thyroid that develops over 24 to 48 hours, sometimes with a sore throat or fever.

There may be an overactive phase with nervousness, tremor, palpitations, insomnia and feeling warmer than usual, sometimes followed by an underactive phase with slowness, fatigue and feeling colder. Diagnosis is by examination and blood tests, and an iodine uptake scan may be used to rule out other causes of overactivity. Low uptake confirms the diagnosis.

Some people recover without treatment, or with anti-inflammatory drugs. If pain and other symptoms persist, a short course of steroids may be used, normally for only one or two months at a gradually reducing dose. People usually recover in two to five months.

This is usually temporary and occurs after pregnancy, especially in women with thyroid autoantibodies. It usually shows up in the first six months after birth. The thyroid may be a little swollen but is almost never painful. The BTF says it usually starts with an overactive phase that may settle on its own or progress to an underactive phase, and that the underactive phase can present as postnatal depression.

Blood tests for thyroid hormones and autoantibodies help to separate it from Graves' disease, and a low uptake on a scan can be done safely with minimal interruption to breastfeeding. Mild cases may need no treatment. A beta blocker can relieve troublesome overactive symptoms and levothyroxine treats troublesome underactive ones, and neither interferes with breastfeeding.

Most women recover completely. Those on levothyroxine can usually stop after six to 12 months, but abnormal tests more than a year after birth are unlikely to resolve alone. It often returns after later pregnancies and raises the risk of permanent thyroid disease in future, so the BTF advises testing after each birth, usually at two to three months, and yearly blood tests afterwards.

The BTF lists medicines that can cause thyroiditis, including amiodarone, lithium, sunitinib, axitinib, interferons, pembrolizumab, nivolumab and ipilimumab. In many cases it resolves without treatment. With others, such as amiodarone, steroid treatment may be needed. Never stop a prescribed medicine without advice, because the underlying illness it treats matters too.

Autoimmune thyroiditis is a process in which the immune system attacks the thyroid cells as though they were foreign. The BTF says mild thyroiditis may occur in up to 20% of otherwise healthy women, with a four- to ten-fold lower frequency in men, but only about 10% of those people become unwell. Hashimoto's thyroiditis is the commonest form. Typical features are developing underactivity and sometimes a painless goitre.

It is diagnosed by measuring antibodies, followed by thyroid hormone tests, and ultrasound may show typical features. If the thyroid is damaged, levothyroxine replaces the missing hormones. It tends to run in families, and if the family history is strong, relatives may be screened for antibodies.

Outlook depends on type. The BTF says thyroiditis is not always permanent. Sub-acute and postpartum types usually settle, with small proportions left with lasting underactivity. Autoimmune thyroiditis often leads to lifelong levothyroxine.

Because some people develop an underactive thyroid years after an episode, follow-up thyroid blood tests are sensible. The BTF recommends yearly checks after postpartum thyroiditis. The NHS says levothyroxine needs regular blood tests to check you are on the right dose.

See a GP if you think you may have thyroid symptoms, a painful or swollen neck, or new palpitations, tremor or marked tiredness, especially after a viral illness or in the months after having a baby. The NHS says an underactive thyroid can be hard to spot because symptoms are common to other conditions, so a blood test helps.

The NHS says an overactive thyroid can sometimes lead to a thyroid storm, a sudden and life-threatening flare-up of symptoms. If you have a known overactive thyroid and develop a very fast or irregular heartbeat, high temperature, severe agitation or confusion, call 999. The BTF says the underactive phase of postpartum thyroiditis can present as postnatal depression, so raise low mood after childbirth with a GP or midwife promptly.

Most people are diagnosed through the GP with blood tests, and referred to an endocrinologist if the picture is unclear, symptoms are severe, or the thyroid is painful and not settling. Scans may be arranged in hospital.

Private endocrinology offers quicker appointments and scans. Whichever route you use, ask which type of thyroiditis is suspected, when tests will be repeated, and what would trigger starting or stopping treatment.