Subacute thyroiditis: clinical characteristics and treatment outcome in fifty-six consecutive patients diagnosed between 1999 and 2005

Abstract

Objective: To identify predictive factors of clinical outcome of subacute thyroiditis.

Design: Retrospective case series of 56 consecutive patients treated in 3 outpatient clinics between 1999 and 2005. Medical records were reviewed for demographic data, seasonal disease distribution, laboratory and clinical course, treatment, and short-term outcome.

Main outcome: Mean age was 48.6+/-12 yr; 70% were females. Twenty-five percent had antithyroid antibodies and 9% had recurrent disease. Differences in occurrence by season were not significant (p=0.28). Ultrasound, performed in 35 patients, revealed thyroid nodules in 25 (median size, 17 mm). Ten patients received no treatment, and 43 received either non-steroidal anti-inflammatory drugs (NSAID) (no.=25) or glucocorticoids (no.=18); data for 3 patients were missing. Median disease duration was 77 days; mean peak free T4 (FT4) level was 43.7+/-25.3 pmol/l. A hypothyroid phase was documented in 31 patients, and remained permanent in 6. Peak FT4 level, but not erythrocyte sedimentation rate or clinical score, was positively correlated with the highest TSH level and with disease duration. Untreated patients had less severe clinical disease than treated patients, but a similar outcome. Patients given glucocorticoids had a shorter overall disease duration (p=0.03), with no differences in duration of hyperthyroidism, peak FT4 or highest TSH levels, compared with patients given NSAID.

Conclusion: Subacute thyroiditis follows an unpredictable clinical course that is hardly affected by its clinical features or treatment.