History and exam

Key diagnostic factors

common

heat intolerance

Seen in 25% of patients with thyrotoxicosis.[2][3]​​

nervousness

Seen in 44% of patients with thyrotoxicosis.[2][3]​​

small non-tender goitre

Seen in 43% of patients with thyrotoxicosis.[2][3]​​

tremulousness

During thyrotoxic phase.

Other diagnostic factors

common

palpitations

Seen in 29% of patients with thyrotoxicosis.[2]​[3]​​

weight loss

Seen in 33% of patients with thyrotoxicosis.[2]​[3]​​

excessive fatigue

During both the thyrotoxic and hypothyroid phases.

bloating

During hypothyroid phase.

muscle cramps

During hypothyroid phase.

weight gain

During hypothyroid phase.

poor concentration

During both the thyrotoxic and hypothyroid phases.

cold intolerance

During hypothyroid phase.

tachycardia

During thyrotoxic phase.

Risk factors

strong

postnatal period

Postnatal thyroiditis occurs after 7% of pregnancies (including after miscarriage and medical abortion [range 1% to 17%]); only one third of these patients present with symptomatic thyrotoxicosis.[5]​​[7]

Note that postnatal thyroid dysfunction may not be recognised by women who attribute symptoms to lack of sleep and breastfeeding.[18]

thyroid peroxidase (TPO) antibodies

One third of women with positive TPO develop postnatal thyroiditis, an 11-fold increased risk compared with controls.[7][19]

Patients with very high titres of TPO antibodies are at increased risk of permanent hypothyroidism.

immunomodulatory therapy

Thyroid dysfunction is seen in up to 40% of patients treated with immunomodulatory drugs such as interferon alfa, tyrosine kinase inhibitors (e.g., sunitinib), and monoclonal antibodies (e.g., alemtuzumab, ipilimumab, nivolumab). However, only a minority of these patients present with transient thyrotoxicosis.[8]​​[9]​​[10]​​[11]​​[12]

lithium therapy

Lithium increases the incidence of painless thyroiditis by at least 5-fold.[6]

amiodarone therapy

Amiodarone may induce thyrotoxicosis in as many as 57% of patients and hypothyroidism in up to 43%, although estimates vary significantly between studies.[15][16]

type 1 diabetes and other autoimmune conditions

Patients with underlying autoimmune disorders are more likely to develop painless thyroiditis. For example, those with type 1 diabetes have a 3-fold risk of postnatal thyroiditis compared with controls.[20]

weak

female sex

Women are twice as likely to develop the condition.[2][3]

autoimmune family history

Autoimmunity is frequently familial.

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