A gland at the front of the neck that makes thyroid hormones, which regulate metabolism, including growth and how much energy the body uses.

An underactive thyroid can cause tiredness, feeling cold, weight gain, constipation, dry skin, hair loss and low mood.
An overactive thyroid can cause a rapid pulse, shaking hands, sweating, weight loss and anxiety.
Hashimoto's disease is the most common cause of an underactive thyroid in Australia, according to healthdirect. Graves' disease is the most common cause of an overactive thyroid.

How it works

The thyroid uses iodine to make two main hormones, thyroxine (T4) and tri-iodothyronine (T3). T3 is more active but is made in smaller amounts. The more T3 and T4 in the blood, the faster the metabolism. Thyroid hormones also influence energy levels, body temperature and calcium levels.

The pituitary gland controls the thyroid by producing thyroid stimulating hormone (TSH). When thyroid hormone is low, the pituitary makes more TSH, and when it is high, the pituitary makes less, which is why TSH is the first thyroid blood test.

Connections

5 connections on the map. Select a topic to read its page.

Thyroid gland is part of

Hormone (endocrine) system
Hormones made in the thyroid influence metabolism, energy levels, body temperature and calcium levels.
Source: healthdirect Australia, Endocrine glands and their hormones

Thyroid gland includes

Thyroid hormone production
The thyroid uses iodine from your diet to make thyroid hormones.
Sources: Pathology Tests Explained, Thyroid function tests; Better Health Channel (Victorian Government), Thyroid gland

Thyroid gland makes

Thyroid hormones (T4 and T3)
The thyroid makes thyroxine (T4) and tri-iodothyronine (T3). T3 is more active but is made in smaller amounts.
Source: Better Health Channel (Victorian Government), Thyroid gland

Thyroid gland is linked with

Heart palpitations
An overactive thyroid is one cause of heart palpitations, according to healthdirect.
Source: healthdirect Australia, Heart palpitations

Thyroid gland is measured by

Thyroid function tests (TSH, free T4, free T3)
Testing TSH, free T4 and free T3 shows whether there is a thyroid or pituitary problem.
Sources: Pathology Tests Explained, Thyroid stimulating hormone (TSH); Pathology Tests Explained, Thyroid function tests

Lab tests

Medicines and supplements

General education only. Never start, stop or change a medicine without your prescriber.

Lithium and other mood stabilisersMental health

Sources

Thyroid glandBetter Health Channel (Victorian Government), last reviewed 6 December 2015
Endocrine glands and their hormoneshealthdirect Australia, last reviewed December 2024
Hypothyroidism (underactive thyroid)healthdirect Australia, last reviewed October 2024
Thyroid function testsPathology Tests Explained, last reviewed 9 January 2025
Foods high in iodinehealthdirect Australia, last reviewed April 2025

Each connection above names its own source. See every source AskBioMap uses.

Summarised from the Better Health Channel, healthdirect and Pathology Tests Explained. Sources read on 13, 16 and 19 October 2026. General education only, not medical advice. Spotted a mistake? Please tell us through the HuBu-Intel contact page.

In brief