Improving laboratory stewardship through benchmarking: A focus on thyroid function tests ordering

Thyroid function tests, particularly thyroid-stimulating hormone (TSH) and free thyroxine (fT4), are among the most frequently ordered laboratory tests. This study evaluates longitudinal trends in thyroid testing utilization, assesses the impact of TSH-first reflex testing, and examines specialty-specific differences in test ordering patterns under the PLUGS (Patient-Centered Laboratory Utilization Guidance Services) benchmarking guidelines.

We analyzed TSH and fT4 test volumes from the year 2009 to 2023. A TSH reflex algorithm, which automatically orders fT4 following an abnormal TSH, was implemented in 2016. The metrics were evaluated using the TSH to fT4 ratio (TSH/fT4) and the percentage of fT4 tests associated with abnormal TSH. Specialty-specific differences were assessed by categorizing providers' specialty, comparing benchmark patterns and diagnostic codes.

Both TSH and fT4 testing volume increased significantly from 2009 to 2023. After the implementation of TSH-first reflex algorithm, TSH/fT4 stabilized (∼3.7) and the percentage of fT4 tests associated with abnormal TSH increased significantly from 26 % to 39 %. Providers from primary care demonstrated stronger adherence to the reflex testing, whereas endocrinology and oncology required more tailored approaches.

This first longitudinal analysis of thyroid testing under the PLUGS benchmark guidelines highlights improved efficiency following reflex test implementation, though specialty-specific differences persist. Consensus-based benchmarks and laboratory stewardship initiatives further enhance test utilization efficiency, optimize workflow, and ensure appropriate thyroid function testing across diverse clinical settings.