Hyperthyroidism and hypothyroidism: the signs !

Syndrome

The thyroid sets the body's speed: with too much hormone everything speeds up, with too little everything slows down.

Updated 2026-11-01

See it in 3D: Thyroid gland · Pituitary gland · Hypothalamus

What it is

Thyroid hormones set the pace of metabolism and the sensitivity of the heart and nervous system to adrenaline. Their excess (hyperthyroidism) and deficiency (hypothyroidism) produce nearly opposite pictures that can be recognized on examination. Comparing the two side by side is the easiest way to remember them.

Key findings

Neck: size, consistency and nodules of the thyroid; a bruit in Graves disease.
Eyes: lid retraction and stare in hyperthyroidism; exophthalmos in Graves; puffy lids in hypothyroidism.
Pulse and rhythm: tachycardia or atrial fibrillation versus bradycardia.
Reflexes: brisk versus a slow relaxation phase.
Skin and hair: warm, moist and fine versus cold, dry, coarse and with hair loss.
Fine tremor of the outstretched hands in hyperthyroidism.

Pathophysiology

The hypothalamus releases TRH, the pituitary TSH, and the thyroid T4 and T3; thyroid hormones in turn suppress the hypothalamus and pituitary (negative feedback).
T3 raises oxygen use and heat production and increases beta-adrenergic receptors: hence the tachycardia, tremor and heat intolerance of excess.
In deficiency, glycosaminoglycans build up in the dermis and other tissues: non-pitting edema (myxedema), a hoarse voice and macroglossia.
In Graves disease, antibodies that stimulate the TSH receptor cause hyperthyroidism and also act on orbital tissue and pretibial skin.
Primary hypothyroidism raises TSH; central (pituitary or hypothalamic) hypothyroidism leaves it low or normal.

Signs of hyperthyroidism vs hypothyroidism

System	Hyperthyroidism	Hypothyroidism
General and weight	Weight loss with normal or increased appetite	Modest weight gain, tiredness
Temperature and skin	Heat intolerance; warm, moist, fine skin	Cold intolerance; cold, dry, coarse skin; myxedema
Heart	Tachycardia, atrial fibrillation, wide pulse pressure	Bradycardia, pericardial effusion
Nervous system	Fine tremor, anxiety, insomnia, brisk reflexes	Slowed thinking, drowsiness, slow-relaxing reflexes
Gut	Frequent bowel movements	Constipation
Eyes	Lid retraction, stare; exophthalmos in Graves	Periorbital puffiness
Muscle and voice	Proximal weakness	Cramps, myalgia, hoarse voice
Menstruation	Light or absent	Heavy or irregular

Common causes

Hyperthyroidism: Graves disease (the commonest), toxic multinodular goiter, toxic adenoma, thyroiditis, iodine excess and excess thyroid hormone taken as medicine.
Hypothyroidism: Hashimoto thyroiditis (the commonest where iodine intake is sufficient), iodine deficiency, past surgery or radioiodine, drugs such as amiodarone and lithium, and congenital causes.
Congenital hypothyroidism: found by newborn screening because it shows almost no signs at birth.
Central hypothyroidism: pituitary or hypothalamic disease.

Tests that confirm it

TSH as the first test and free T4 to confirm.
TSH-receptor antibodies (Graves) or anti-peroxidase antibodies (Hashimoto).
Thyroid ultrasound if there are nodules; a radionuclide scan to separate causes of hyperthyroidism.

Test yourself

Think of the answer, then tap the question to see it.

Why does hyperthyroidism cause tachycardia and tremor?

Thyroid hormones increase the number and sensitivity of beta-adrenergic receptors, so the heart and nervous system respond more strongly to adrenaline.

Which signs belong to Graves disease and not to every hyperthyroidism?

Ophthalmopathy with exophthalmos, pretibial dermopathy and a diffuse goiter with a bruit, caused by antibodies against the TSH receptor.

Which tendon-reflex finding suggests hypothyroidism?

A slow relaxation phase of the reflex, easiest to see at the ankle (Achilles) reflex.

How can hyperthyroidism present in an older adult?

As 'apathetic' hyperthyroidism: apathy, depression, weight loss and atrial fibrillation, without the hyperactivity typical of younger patients.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: Hyperthyroidism | Overactive Thyroid | MedlinePlus (MedlinePlus, U.S. National Library of Medicine, 2026); Hypothyroidism | Hashimoto's Disease | MedlinePlus (MedlinePlus, U.S. National Library of Medicine, 2026); 17.4 The Thyroid Gland - Anatomy and Physiology 2e | OpenStax (OpenStax, Rice University, 2022).

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Representative model, for educational purposes only.