What are thyroid disorders?

Thyroid disorders encompass conditions of underactive thyroid (hypothyroidism), overactive thyroid (hyperthyroidism), thyroid enlargement (goitre), thyroid nodules, and thyroid cancer. The thyroid gland — a butterfly-shaped gland in the neck — produces hormones (T3 and T4) that regulate metabolism, temperature, heart rate, growth and cognitive function. Thyroid disorders affect over 750 million people globally, with women affected approximately 10 times more frequently than men.

What is hypothyroidism?

Hypothyroidism (underactive thyroid) is insufficient thyroid hormone production. Causes: Hashimoto's thyroiditis (autoimmune — the most common cause); iodine deficiency; post-thyroid surgery or radioactive iodine treatment; and some medications (lithium, amiodarone). Symptoms: fatigue, weight gain, constipation, cold intolerance, dry skin, depression, cognitive slowing and — in pregnancy — risk of miscarriage and fetal brain development impairment. Treatment: daily oral levothyroxine — highly effective and well-tolerated.

What is hyperthyroidism?

Hyperthyroidism is excessive thyroid hormone production — causing a hypermetabolic state. Symptoms: weight loss despite increased appetite; palpitations and fast heart rate; sweating; heat intolerance; anxiety and irritability; tremor; and in Graves' disease — exophthalmos (bulging eyes). Most common cause: Graves' disease (TSH receptor antibodies stimulate the thyroid). Treated with antithyroid drugs (carbimazole, methimazole, propylthiouracil), radioactive iodine ablation, or surgery (thyroidectomy).

How does iodine deficiency cause disease?

Iodine is an essential trace element required for thyroid hormone synthesis. Deficiency causes: goitre (thyroid enlargement as compensation); hypothyroidism; and — the most serious consequence — congenital hypothyroidism when a pregnant woman is deficient. Fetal thyroid hormone is essential for brain development: severe deficiency causes cretinism (profound intellectual disability, growth stunting, deafness). Mild-moderate deficiency causes lesser cognitive impairment affecting school performance and productivity. Universal salt iodisation eliminates most iodine deficiency disorders.

What is universal salt iodisation?

Universal salt iodisation (USI) — adding iodine (potassium iodate) to all salt used for food processing and table salt — is the WHO/UNICEF recommended strategy for eliminating iodine deficiency. It is one of the most cost-effective public health interventions: approximately $0.05 per person per year. WHO targets >90% of households using iodised salt; as of 2024, approximately 90% of countries have USI policies. Georgia has implemented salt iodisation, substantially reducing iodine deficiency disorders.

What is Graves' disease?

Graves' disease is the most common cause of hyperthyroidism — an autoimmune condition in which TSH receptor antibodies stimulate the thyroid to produce excessive hormone. It uniquely causes exophthalmos (proptosis — bulging eyes from orbital inflammation) that can cause visual complications. Graves' disease is more common in women aged 20-50, and often triggered by stress, pregnancy or smoking. Treatment options: antithyroid drugs (remission in approximately 50%); radioactive iodine (highly effective, may cause hypothyroidism); surgery (thyroidectomy).

What is Hashimoto's thyroiditis?

Hashimoto's thyroiditis is the most common cause of hypothyroidism — an autoimmune condition in which the immune system gradually destroys thyroid tissue. Characterised by elevated anti-TPO (thyroid peroxidase) antibodies. It progresses slowly over years from normal thyroid function through subclinical hypothyroidism to overt hypothyroidism. It is often associated with other autoimmune conditions (type 1 diabetes, rheumatoid arthritis, coeliac disease). Treatment: levothyroxine once thyroid function becomes insufficient.

What is thyroid cancer?

Thyroid cancer is the fastest-growing cancer diagnosis globally — with 586,000 new cases in 2020. Four main types: papillary (80% — excellent prognosis); follicular (10-15% — good prognosis); medullary (5% — from parafollicular C cells, familial in 25%); and anaplastic (1% — very aggressive, rapid progression, poor prognosis). Most thyroid cancer is papillary — highly curable with thyroidectomy plus selective radioactive iodine (RAI) and thyroid hormone suppression. The dramatic rise in diagnosis partly reflects overdetection of small, clinically insignificant papillary microcarcinomas by ultrasound.

What is the thyroid cancer overdiagnosis debate?

Thyroid cancer incidence has risen dramatically over 30 years, primarily from detection of small papillary microcarcinomas (<1 cm) through ultrasound imaging done for other reasons. Many of these would never have caused symptoms. Active surveillance (monitoring without immediate surgery) for papillary microcarcinomas is now recommended by several guidelines (Japan, Korea, US) — showing that most do not progress. This avoids the morbidity of unnecessary thyroidectomy (permanent hypothyroidism, hypoparathyroidism, recurrent laryngeal nerve injury).

How is thyroid function tested?

TSH (thyroid-stimulating hormone) is the primary screening test — a single blood test that sensitively detects both hypothyroidism (elevated TSH) and hyperthyroidism (suppressed TSH). Free T4 and free T3 are measured for confirmation and severity assessment. Autoimmune thyroid antibodies (anti-TPO, anti-thyroglobulin for Hashimoto's; TSH receptor antibodies for Graves') identify the cause. Thyroid ultrasound assesses nodules; thyroid scintigraphy assesses function and nodule characteristics. Fine needle aspiration cytology evaluates suspicious nodules.

Should thyroid function be routinely screened?

Universal thyroid screening is not currently recommended for asymptomatic adults. However, targeted screening is recommended for: pregnant women (hypothyroidism harms fetal brain development); neonates (congenital hypothyroidism — universally screened in high-income countries); women over 50 with symptoms; people with Down syndrome, Type 1 diabetes, autoimmune disease or family history; and those on lithium or amiodarone.

How does GMJ News cover thyroid disorders?

GMJ News covers WHO iodine deficiency data, universal salt iodisation progress, thyroid cancer epidemiology and the overdiagnosis debate, Hashimoto's and Graves' disease management, and neonatal thyroid screening. Iodine deficiency and thyroid disorders are relevant to Georgia's public health programme — iodised salt availability and neonatal screening are PHIG priorities.

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Thyroid Disorders

Q: How is thyroid function tested?

TSH (thyroid-stimulating hormone) is the primary screening test — a single blood test that sensitively detects both hypothyroidism (elevated TSH) and hyperthyroidism (suppressed TSH). Free T4 and free T3 are measured for confirmation and severity assessment. Autoimmune thyroid antibodies (anti-TPO, anti-thyroglobulin for Hashimoto's; TSH receptor antibodies for Graves') identify the cause. Thyroid ultrasound assesses nodules; thyroid scintigraphy assesses function and nodule characteristics. Fine needle aspiration cytology evaluates suspicious nodules.

GMJ News knowledge hub · last reviewed September 2026 · Georgian Medical Journal

Summary Statistics Glossary GMJ news FAQ Documents Organizations Research

Thyroid disorders — including hypothyroidism, hyperthyroidism, goitre, thyroid nodules and thyroid cancer — are among the world's most common endocrine diseases, estimated to affect over 750 million people globally, with many more undiagnosed (WHO). Iodine deficiency — affecting approximately 1.9 billion people at risk globally — remains the world's most preventable cause of intellectual disability through congenital hypothyroidism. Thyroid cancer is the fastest-growing cancer diagnosis globally (partly from overdiagnosis), with 586,000 new cases in 2020 — though most are curable with standard treatment.

Key messages

750 million affected

Thyroid disorders — including hypothyroidism, hyperthyroidism, goitre and thyroid cancer — are among the world's most common endocrine diseases, affecting over 750 million people globally, with many more undiagnosed (WHO).

Iodine deficiency — 1.9 billion at risk

Iodine deficiency — causing goitre, hypothyroidism and — critically — congenital hypothyroidism causing permanent intellectual disability — remains the world's leading preventable cause of intellectual disability, with 1.9 billion people at risk globally.

Universal salt iodisation

Universal salt iodisation (USI) — adding iodine to all table and cooking salt — is the primary strategy for eliminating iodine deficiency. WHO and UNICEF target >90% of households using iodised salt. As of 2024, the majority of the world's population has access to iodised salt.

Thyroid cancer fastest growing

Thyroid cancer is the fastest-growing cancer diagnosis globally — with 586,000 new cases in 2020, largely driven by improved imaging detecting small papillary cancers. Most thyroid cancer is papillary carcinoma — highly curable with surgery, radioactive iodine and thyroid hormone suppression.

Hypothyroidism — underdiagnosed

Hypothyroidism — insufficient thyroid hormone — is extremely common, especially in women and older adults. Many cases are subclinical and clinically undetected. It causes fatigue, weight gain, depression, cold intolerance and cognitive impairment — highly treatable with levothyroxine.

Graves' disease

Graves' disease is the most common cause of hyperthyroidism — an autoimmune condition in which antibodies stimulate the thyroid to produce excessive hormone. Causes weight loss, palpitations, sweating, anxiety and exophthalmos (eye protrusion). Treated with antithyroid drugs, radioactive iodine or surgery.

Key statistics

750M+

people with thyroid disorders

WHO/ATA

1.9B

at risk from iodine deficiency

WHO/UNICEF

586K

new thyroid cancer cases/year (2020)

IARC GLOBOCAN

fastest-growing cancer globally (thyroid)

IARC

2B+

people with access to iodised salt

WHO/UNICEF

10:1

female:male ratio for thyroid disease

WHO/ATA

Countries achieving universal salt iodisation coverage >90% — WHO/UNICEF progress

Source: WHO/UNICEF Network for the Sustained Elimination of Iodine Deficiency. Progress 1990-2022.

Glossary of key terms

TSH (thyroid-stimulating hormone)
WHO/ATAThe pituitary hormone that stimulates thyroid hormone production — the primary test for thyroid function. Elevated TSH indicates hypothyroidism (the pituitary working harder to stimulate an underactive thyroid); suppressed TSH indicates hyperthyroidism.

Hypothyroidism
WHO/ATAInsufficient thyroid hormone production — causing fatigue, weight gain, constipation, cold intolerance, depression, cognitive impairment, and in severe cases myxoedema coma. Treated with daily oral levothyroxine (T4 replacement). Most common endocrine disorder globally.

Hyperthyroidism
WHO/ETAExcessive thyroid hormone — causing weight loss, palpitations, sweating, anxiety, tremor, heat intolerance and (in Graves') exophthalmos. Most common cause: Graves' disease (autoimmune); toxic nodular goitre. Treated with antithyroid drugs (carbimazole/propylthiouracil), radioactive iodine or surgery.

Goitre
WHOEnlargement of the thyroid gland — visible swelling in the neck. Most commonly caused by iodine deficiency (the thyroid enlarges to compensate for inadequate iodine intake). Can also result from autoimmune disease, thyroid nodules or thyroid cancer.

Congenital hypothyroidism
WHO/AAEMAbsent or severely reduced thyroid function from birth — the most common preventable cause of intellectual disability. Detected by neonatal screening (TSH in heel-prick blood spot). Early treatment with levothyroxine from the first days of life enables normal cognitive development.

Papillary thyroid carcinoma
WHO/ATAThe most common thyroid cancer type (approximately 80%) — typically slow-growing, excellent prognosis (10-year survival >95%). Often overdiagnosed through ultrasound detection of small, clinically insignificant tumours. Standard treatment: thyroidectomy; selective radioactive iodine (RAI); thyroid hormone suppression.