Time-lag between symptom onset and laboratory findings in patients with subacute thyroiditis

Objective: The objective of this study was to delineate the frequency of delayed diagnosis in cases of subacute thyroiditis (SAT) and intervals between onset of clinical symptoms and appearance of abnormal laboratory findings. Methods: We reviewed the medical records of 27 patients (7 men and 20 women) with SAT who visited our hospital between 2007 and 2013. Results: On presentation to the hospital, 5 of 27 SAT cases (18.5%) showed normal laboratory findings. Among these 5 cases, the mean interval between symptom onset and thyrotropin (TSH) suppression was 6.3 weeks, and the mean interval to elevation of fT4 was 6.7 weeks. The longest interval from symptom onset to appearance of an abnormal laboratory finding was 11 weeks. Conclusion: Sometimes time-lag exists between onset of clinical symptoms and the appearance of abnormal laboratory findings in patients with SAT. The possibility of this disease should not be excluded from the differential diagnoses for patients with clinical symptoms consistent with SAT but showing normal laboratory findings.