Aim: Quality improvement studies in clinical laboratories play a vital role in achieving accurate and reliable patient results. Measurement uncertainty is important for the quality and reliability of test results. Since laboratory results inherently involve uncertainty, ISO 15189 Accreditation Standards recommend reporting patient results accompanied by measurement uncertainty. The aim of our study is to determine the measurement uncertainty and compare it with the total allowable error (TEa%) values determined by international organizations in order to increase the accuracy and reliability of the specific hormone tests studied in our laboratory.

Material and Methods: Our study was conducted at the Medical Biochemistry Laboratory of Health Sciences University İzmir Tepecik Training and Research Hospital. To determine the measurement uncertainties of adrenocorticotropic hormone (ACTH), growth hormone, insulin-like growth factor-1 (IGF-1), C-peptide, thyroglobulin, 25-hydroxy vitamin D, and parathormone (PTH) parameters, the 3-month period from October to December 2022 internal quality control data and 12-month external quality control data from January to December 2022 were used. The measurement uncertainty of the tests was calculated according to the Nordtest guideline. These values were evaluated based on TEa% criteria established by three different international organizations.

Results: The measurement uncertainties of ACTH, growth hormone, IGF-1, C-peptide, thyroglobulin, 25-hydroxy vitamin D, and PTH tests were 11.53, 14.83, 12.35, 7.91, 18.18, 20.95, 15.69 for level 1 at 95% confidence interval; for level 2, it was calculated as 10.99, 13.65, 13.15, 5.87, 17.24, 17.05, 16.56 respectively. The measurement uncertainties of the C-peptide, thyroglobulin, and PTH tests for level 3 were 6.98, 16.03, and 15.51, respectively.

Conclusion: While the expanded measurement uncertainties of growth hormone and C-peptide were determined below the TEa% values determined by international organizations, the measurement uncertainties of the ACTH and IGF-1 tests were found to be borderline high compared to the Royal College of Pathologists of Australasia (RCPA) TEa% values at both levels. While the measurement uncertainties of thyroglobulin, 25-hydroxy vitamin D, and PTH parameters were higher than the RCPA TEa% values at both levels, they were found below the TEa% values determined by other international organizations.