Subacute thyroiditis in pregnancy: a narrative review

Thyroid dysfunction can adversely affect pregnancy outcomes. Apart from gestational thyrotoxicosis, thyroid dysfunction during pregnancy shares similar etiologies with the non-gravid state. Graves' disease is the most common cause of spontaneous hyperthyroidism in pregnancy, followed by thyroid autonomy. Although subacute thyroiditis is a less common cause of thyrotoxicosis in pregnancy, its associated pain, systemic symptoms, and thyroid dysfunction can present diagnostic and therapeutic challenges. In its painful form, subacute thyroiditis may lead to severe disability, with systemic glucocorticoids being the best effective treatment option. When painless, the condition often comes to medical attention due to thyroid dysfunction. During the thyrotoxic phase, subacute thyroiditis should be differentiated from gestational thyrotoxicosis, Graves' disease, and thyroid autonomy. Additionally, the transient hypothyroid phase may be misdiagnosed as permanent hypothyroidism, such as in Hashimoto's thyroiditis. Once properly diagnosed, management is symptomatic and focused on correcting the predominant abnormality. In this review, we summarize the current reported cases of subacute thyroiditis in pregnancy and discuss the challenges in diagnosis and management. Clinical trial number Not applicable.