Overactive thyroid (hyperthyroidism) : symptoms, diagnosis and treatment

Written by: Dr Rasha Mukhtar
Published: | Updated: 28/10/2021
Edited by: Kalum Alleyne

While many of us are aware of the thyroid gland, few are conscious of its importance and the dangers of it not working properly. Dr Rasha Mukhtar, a vastly experienced consultant endocrinologist, shares her expertise on this topic, answering the most important questions regarding hyperthyroidism.


Increased sweating caused by an overactive thyroid


What are the symptoms of an overactive thyroid?

The thyroid gland is central in controlling a number of the body’s metabolic processes, so when overactive it affects energy, heart rate and other systems. The symptoms of an overactive thyroid include:

  • Faster heart beat
  • Increased sweating
  • Weight loss despite a healthy appetite
  • Enhanced anxiety
  • Feeling fidgety
  • Difficulty sleeping
  • Tremors of the hands particularly
  • Enhanced bowel habits
  • Women may experience lighter menstrual periods

The combination of these symptoms has been summarised by some patients as feeling like being constantly on a treadmill.


How is an overactive thyroid diagnosed?

Your endocrinologist will first perform a blood test to measure the level of TSH (thyroid stimulating hormone), which is the hormone responsible for controlling thyroid hormones, it is usually suppressed in hyperthyroidism. In addition the active thyroid hormones triiodothyronine (T3), and thyroxine (T4) are assessed. A Low TSH with high T3 and T4 is diagnostic of hyperthyroidism.


Once a diagnosis of hyperthyroidism is made further tests will then be completed to confirm the cause, these include antibody tests and nuclear scans.


What happens If an overactive thyroid is left untreated?

If left untreated, an overactive thyroid can make you extremely unwell. The raised heart rate means the heart is working harder than normal, which can lead to an irregular heartbeat, heart failure and an enhanced risk of stroke.


There is also a risk of developing osteoporosis due to the enhanced metabolism and dysregulation in bone turnover.


When should you visit a doctor?

If you have symptoms which you suspect to be related to an overactive thyroid, particularly an unexplained fast heart rate, tremors, or weight loss, you should visit a doctor so that they can conduct tests if necessary. As the symptoms of hyperthyroidism might be present for a number of other conditions it can sometimes be missed. It is unclear what triggers of hyperthyroidism, some say stress, or viral illness, but the majority of cases have no underlying cause.


How is an overactive thyroid treated?

Your doctor will offer you some tablets which block thyroid activity. Improvement in symptoms are usually noticed fairly quickly once the medication is started but the course is long and may last up to a year or two in order to ensure that the thyroid gland has reverted back to normal.


In some cases, radioactive iodine treatment is offered. However, due to the radiation dose, this treatment comes with a number of precautions that need to be taken after it is administered. It is not suitable for pregnant or breastfeeding women, or in those who have thyroid related eye problems.


Surgery may be recommended if:

  • The thyroid gland is extremely enlarged and causing disfiguration
  • Other treatments are contra-indicated or don’t work

Surgery is often recommended only as a last resort as removal of the whole gland results in permanent hypothyroidism (underactive) requiring life-long thyroid replacement therapy.


What foods should be avoided if you have an overactive thyroid?

Iodine is important for the production of thyroid hormones and hence too much might increase thyroid hormone production. Individuals with hyperthyroidism should avoid excessive amounts of foods rich in iodine such as shellfish and iodised salt. In general a healthy well balanced diet should be adequate.


If you are dealing with hyperthyroidism, you would benefit from the expert care of an experienced endocrinologist. Visit Dr Rasha Mukhtar's profile where you can view her scheduling information and request an appointment with her.

By Dr Rasha Mukhtar
Endocrinology, diabetes & metabolism

Dr Rasha Mukhtar is an esteemed consultant in diabetes and endocrinology based at Frimley Park Hospital. Dr Mukhtar has a busy clinical practice covering the investigation, diagnosis and management of patients with diabetes, obesity, thyroid dysfunctions, calcium disorders, pituitary disease, adrenal problems, hypogonadism, and electrolyte abnormalities. She also runs a diabetes and endocrine antenatal clinic in conjunction with obstetricians and specialist nurses, and can also provide pre-conceptual care.

In addition to her clinical practice, Dr Mukhtar is an active medical educator. Dr Mukhtar is a MRCP PACES examiner and is involved with the General Medical Council. Her research was in dietary interventions and metabolic syndrome, and she has extensive research experience in studies involving diabetes, obesity and cardiovascular risk management. She is a principal and co-investigator for a number of international and multi-centre studies.

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