Silent or subacute (De Quervain's) thyroiditis which is associated with painful thyroid enlargement, systemic upset and a raised ESR/CRP. Thyroiditis can also occur in the postpartum period (in 5% pregnancies).

Diagnostic tests

Transient hyperthyroidism (↑Free T₄, ↓TSH) of 2-4 months duration followed by transient hypothyroidism (↓FT₄, ↑TSH) of 2-9 months duration. A diagnosis of thyroiditis can be confirmed by a thyroid isotope scan (no uptake in the presence of biochemical thyrotoxicosis).

Therapy

Thyroiditis is usually mild and self-limiting and treatment is rarely required. When there are marked systemic symptoms in subacute thyroiditis, systemic steroids may be beneficial. Anti-inflammatory agents are useful for pain relief. If symptomatic hypothyroidism, levothyroxine replacement is appropriate. This should be discontinued after 12 months and the need reassessed. Long term therapy is rarely needed.

(See 6.2.1 Thyroid hormones).

Prognosis

Only 5-10% of subacute thyroiditis remains permanently hypothyroid at 20 years. About 50% of women with postpartum thyroiditis develop permanent hypothyroidism at 10 years.