Utility of Thyroid Function Testing in the Inpatient Setting.

Objective: Previous studies have reported a low value of ordering inpatient thyroid function tests (TFTs), with few changes in clinical management resulting from these tests. This study was designed to evaluate how often testing the thyroid function during hospitalization leads to medication initiation or adjustment and to determine whether the frequency of medication initiation or adjustment differs based on the indication for testing.

Methods: This is a retrospective observational study of 2278 patients who underwent TFTs tested while admitted to an academic hospital during a 5-month period. The indications for ordering TFTs were determined by reviewing clinical documentation, and those with abnormal test results were reviewed to assess whether thyroid medication was initiated or adjusted.

Results: The percentage of abnormal TFTs that led to medication initiation or adjustment was 15.1%, 12.2%, and 6.0%, for those tested based on a history of functional thyroid disease, suspicion of thyroid dysfunction, and reasons not directly related to thyroid dysfunction, respectively. Overall, 63 patients were started on thyroid medication or had their thyroid medication dose adjusted, which represented 10.1% of those with abnormal TFTs and only 2.8% of those tested.

Conclusion: Abnormal TFTs are common, but a disproportionate number of tests are needed to find a small percentage of clinically significant thyroid dysfunction, of which only a low percentage leads to changes in management. Education on this topic should be provided to inpatient providers to limit thyroid function testing to instances in which they are clinically indicated and abnormal results would lead to changes in management.