Aim: This study aims to evaluate repeated tests and unnecessary repeated laboratory tests based on minimum retest intervals.

Materials and Methods: Data regarding thyroid-stimulating hormone (TSH), ferritin, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) tests analysed in the İzmir Kemalpaşa State Hospital laboratory during 2023 were retrospectively obtained from the laboratory information system. Minimum retest intervals for these tests were determined according to the National Minimum Re-testing Intervals in Pathology guidelines developed by The Royal College of Pathologists, The Association for Clinical Biochemistry and Laboratory Medicine, and The Institute of Biomedical Science. Accordingly, the minimum retest intervals were defined as 28 days for TSH, 30 days for ferritin, 24 hours for CRP, and 7 days for ESR. Tests performed more than once per patient during the study period were categorized as repeated tests, whereas tests repeated within a period shorter than the minimum retest interval were classified as unnecessary repeated tests.

Results: The total numbers of TSH, ferritin, CRP, and ESR tests performed in the laboratory were 27,516, 19,836, 32,100, and 7,200, respectively. The number (percentage) of repeated tests was 1,402 (5.10%) for TSH, 1,726 (8.70%) for ferritin, 1,827 (5.69%) for CRP, and 1,020 (14.2%) for ESR. Among these repeated tests, the numbers (percentages) classified as unnecessary repeated tests were 148 (10.6%), 134 (7.76%), 118 (6.46%), and 107 (10.49%), respectively.

Conclusion: Unnecessary repeated laboratory tests contribute significantly to increased healthcare costs and workload inefficiencies. Increasing awareness among healthcare administrators and clinicians regarding the prevalence of unnecessary testing is critical for improving resource utilization and reducing avoidable expenditures.