Diagnostic Approach to Normal TSH with High T4

Initial Evaluation and Laboratory Testing

• Repeat thyroid function tests over a 3-6 month interval to confirm persistent abnormality, as recommended for all thyroid dysfunction screening, according to the American College of Physicians 1, 2, 3
• Check thyroid antibodies to assess for autoimmune disease, as suggested by Praxis Medical Insights 4

Differential Diagnosis and Diagnostic Workup

• TSH values can be affected by technical issues with TSH assay, abnormal TSH isoforms, or heterophilic antibodies, which should be considered especially if results don't fit the clinical picture, as noted by Praxis Medical Insights 4