Projected Impact of Predefined Reflex Testing Algorithms on Thyroid Function and Prostate-Specific Antigen Testing: A Real-World Laboratory Stewardship Study

Background/Objectives: Reflex testing may improve laboratory stewardship by limiting downstream analyses to situations in which additional testing is supported by the result of an initial test. This study evaluated the projected impact of predefined reflex testing algorithms on thyroid function and prostate-specific antigen (PSA) test utilization and laboratory expenditure.

Methods

This observational modelling study included clinician-initiated thyroid function and PSA testing sessions recorded at a tertiary-care hospital in Türkiye during 2022. Clinician-requested tests and corresponding laboratory results were compared with predefined reflex algorithms applied retrospectively at the testing-session level. For thyroid testing, thyroid-stimulating hormone (TSH) was used as the initial test; free thyroxine (FT4) was projected for elevated TSH, and both FT4 and free triiodothyronine (FT3) for decreased TSH. For PSA testing, free PSA was projected only when total PSA was 4.0–10.0 ng/mL. Observed clinician-initiated testing was compared descriptively with projected algorithm-based testing, including downstream test utilization and laboratory expenditure.