What are the symptoms of an underactive or overactive thyroid?

The thyroid is a small gland at the front of the neck. Its hormones help regulate energy use, temperature, heart rate, bowel function and other body processes. An underactive thyroid, or hypothyroidism, does not make enough thyroid hormone. An overactive thyroid, or hyperthyroidism, makes too much.

An underactive pattern can include persistent tiredness, feeling cold, constipation, dry skin or hair, poor concentration, low mood, muscle aches, a slower heart rate, heavier or irregular periods and gradual weight gain. Symptoms often develop slowly and vary between people.

An overactive pattern can include feeling hot or sweaty, a racing or irregular heartbeat, tremor, anxiety or irritability, poor sleep, muscle weakness, more frequent or loose bowel motions, lighter or irregular periods and weight loss despite an unchanged or increased appetite.

Either pattern can include fatigue, period changes, hair changes or a swelling at the front of the neck. Symptoms alone cannot show whether thyroid hormone is high, low or normal, and having several symptoms does not confirm thyroid disease.

Hashimoto disease is the most common cause of an underactive thyroid in Australia. It is an autoimmune condition in which the immune system damages the thyroid. An underactive thyroid can also follow thyroid surgery, radioactive iodine treatment, some medicines or thyroid inflammation.

Graves disease is the most common cause of an overactive thyroid in Australia. It is also autoimmune, but its antibodies stimulate the thyroid. Overactive nodules can make excess hormone independently of the gland's usual control signals.

Thyroiditis means inflammation of the gland. It can release stored hormone and cause a temporary overactive phase, sometimes followed by an underactive phase. Thyroiditis can occur after a viral illness or after giving birth. The cause and phase matter because treatment is not the same for every abnormal result.

Medicines and high-iodine supplements can affect thyroid function. Tell the GP about all prescribed, over-the-counter and complementary products. Do not start kelp, iodine or a product marketed as thyroid support to treat symptoms yourself.

Yes. Tiredness, sleep disturbance, mood or concentration changes, heat intolerance, palpitations, weight change and changing periods can occur around perimenopause or with thyroid dysfunction. One does not exclude the other, and they can coexist.

In people over 45, perimenopause and menopause are usually identified from the symptom and menstrual pattern rather than a routine reproductive-hormone test. A thyroid test may still be useful when the history raises a separate thyroid question.

A GP can consider thyroid, menopause, iron deficiency, sleep, mood, medicines and other possible contributors together. Avoid assuming every symptom has one hormonal cause.

A HerDoc GP can order thyroid-function tests when symptoms, history or examination raise a thyroid question. For most adults without suspected pituitary disease, thyroid-stimulating hormone (TSH) is the usual first test.

If TSH is high, free thyroxine (free T4) helps assess whether the thyroid is underactive. If TSH is low, free T4 and sometimes free triiodothyronine (free T3) help assess an overactive pattern. Different starting tests may be needed during pregnancy, in children, with known thyroid disease or when pituitary disease is possible.

Thyroid antibody tests answer a different question: they can help identify an autoimmune cause such as Hashimoto or Graves disease when the clinical and hormone results support that possibility. They are not a substitute for thyroid-function tests and do not need to be ordered repeatedly without a reason.

Subclinical hypothyroidism means TSH is high while thyroid hormone remains within the reference range. Subclinical hyperthyroidism means TSH is low while thyroid hormone remains within the reference range. Depending on the result and context, the next step may be repeat testing or monitoring rather than automatic treatment.

Recent illness, pregnancy, medicines and supplements can affect results. High biotin intake from some hair, skin or nail supplements can make thyroid results falsely high or low. Tell the GP and pathology service what you take and follow their instructions rather than choosing a stop interval yourself.

A local GP can feel the neck and check findings such as the pulse, reflexes, eyes and skin. A new neck lump, persistent swelling, a changing voice, difficulty swallowing or pressure in the neck needs local assessment. A phone consultation cannot perform this examination.

Blood tests assess thyroid function. Ultrasound assesses structure, such as a lump or enlargement, and is not routinely needed simply because a thyroid blood result is abnormal. Other imaging is selected only when it answers a specific question.

HerDoc can provide referrals, but local appointments, scans and specialist care are arranged with the relevant provider. Ask how soon to attend and check provider availability and costs.

Treatment depends on whether hormone levels are low or high, the cause, symptom severity, pregnancy and other health factors. An underactive thyroid may be treated with prescribed thyroid-hormone replacement and monitored with blood tests.

An overactive thyroid may be treated with medicine that reduces hormone production, radioactive iodine or surgery. Radioactive iodine is not used during pregnancy or breastfeeding. Some people also receive short-term treatment for symptoms such as a fast heart rate. Thyroiditis can follow a different course because stored hormone may be released without the gland producing more hormone.

Do not use another person's thyroid medicine, change a dose, or start iodine, kelp or a thyroid supplement yourself to treat thyroid symptoms. Too much thyroid hormone or iodine can cause harm and can obscure the cause. A doctor should explain the expected benefit, monitoring and important adverse effects of the selected option.

A normal TSH makes common primary thyroid dysfunction less likely in many adults, but the result still needs to be read in context. Timing, recent illness, pregnancy, supplements, medicines and uncommon pituitary conditions can change the testing approach.

Persistent symptoms deserve review even when thyroid tests are normal. The GP may consider iron deficiency, sleep problems, mood, menopause, medicines, infection, other hormone conditions or another cause suggested by your history.

More thyroid tests are not always the best next step. A focused examination, a different test, monitoring or treatment of another identified problem may be more useful.

A HerDoc GP can review the symptom pattern, medicines and supplements, family and pregnancy history, previous results and what has changed. The GP can order thyroid blood tests and provide a referral after individual assessment.

HerDoc consultations are by phone. A local clinician may need to examine your neck, eyes, pulse or other findings, and established thyroid disease may need ongoing local or specialist care. A phone appointment cannot replace urgent or necessary physical assessment.

You do not need to decide which test or diagnosis fits before booking. Have previous reports and the names of medicines and supplements ready if available.

Thyroid function and treatment need pregnancy-specific interpretation. If you have known thyroid disease and are planning pregnancy, arrange a medication and monitoring review. If you have a positive pregnancy test, contact your doctor promptly and tell your maternity team about the thyroid condition.

Do not stop thyroid medicine or change the dose yourself. The safest plan depends on the condition, current treatment and blood results, and some treatments for an overactive thyroid require specialist planning before or during pregnancy.

If the GP orders pathology, HerDoc provides the request details and you arrange collection through a pathology service. Follow the collection instructions rather than assuming you need to fast or stop a supplement.

HerDoc-requested results return to HerDoc for clinical review. A results discussion is arranged separately when needed. Eligible standard follow-up appointments can be bulk billed at $0 with no gap; otherwise, private fees apply.

The next step may be explanation, a repeat test, local examination, a treatment discussion or specialist assessment. If symptoms persist despite normal results, return for review of other possible contributors.

Seek urgent local care if symptoms worsen rather than waiting for a result or follow-up. Follow any instruction from the treating doctor or testing service to act sooner.

The symptoms below need assessment for many possible causes. Do not try to identify a thyroid emergency yourself.

Further information about thyroid symptoms, testing, treatment and menopause overlap is available from these health services and clinical guidelines.