Araştırma Çıktıları
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Item National External Quality Assessment follow-up: 2010-2017 Turkish experience(WALTER DE GRUYTER GMBH, 2019-01-01) Mercan, Ferzane; Serdar, Muhittin A.; Senes, Mehmet; Konukoglu, Dildar; Inal, Tamer Cevat; Alatas, Ozkan; Pinar, Asli; Savci, Ozlem; Guven, Muhammet; Gunduz, Mehmet; Egin, Ertugrul; Tipioglu, Yasal Onder; Tekin, Ahmet; Yucel, DoganObjective: Medical laboratories encounter critical obstacles in External Quality Assessment (EQA) practices that are key to assessment of the analytical period. Present study aims to unveil the challenges in nationwide interlaboratory harmonization and suggest practical solutions. Materials and methods: EQA results of 1941 laboratories participating in 18 different EQA-programs between 2010 and 2017 were examined. Standard Deviation Index (SDI) of each program calculated using 801,028 sample data from 24 different clinical chemical tests were used to conduct a process assessment. Results: There is a significant discrepancy in unsatisfactory performance ratio among different EAQ-programs with an average of 3.4\% (27,074 cases) between 2010 and 2017 and a decreasing trend (similar to 40-50\%) in 7-years. Programs with higher SDI display lower discrepancy rates. Reasons for unaccepted results appear to be data entry errors (8.27-22.2\%), material dilution errors (5-11.4\%), technical problems (3.76-7.9\%)Item Comparison of four immunoassay analyzers for relationship between thyroid stimulating hormone (TSH) and free thyroxine (FT4)(TURKISH BIOCHEM SOC, 2015-01-01) Serdar, Muhittin A.; Ispir, Emre; Ozgurtas, Taner; Gulbahar, Ozlem; Ciraci, Zahid; Pasaoglu, Hatice; Kurt, IsmailObjective: There is an inverse log/linear relationship between TSH and FT4 due to the negative feedback of these hormones on the pituitary. The objective of our study was to compare this relationship of TSH and FT4 between four different immunoassay analyzers. Methods: In our study, four data sets obtained from the database of four different hospital laboratories each using only a single method of measurement was used to evaluate this relationship between TSH and FT4. These data sets with their assay methods include: 21.102 test results measured by Modular E170 Analyzer (Roche Diagnostics, Germany), 20.241 test results measured by Access DxI 800 Unicel (Beckman Coulter, USA), 22.444 test results measured by Architect i2000sr (Abbott Laboratories, Abbott Park, Illinois, U.S.A) and 20.200 test results measured by ADVIA Centaur XP (Siemens Diagnostics, Tarrytown, NY). Inverse logarithmic relationship were determined from each data sets and compared between analyzers. Results: The correlation coefficients were -0.439 {[}95\% CI, (-0.450)- (-0.428)], -0.488 {[}95\% CI, (-0.498)- (-0.478)], -0.353 {[}95\% CI, (-0.364)- (-0.342)], -0.430 {[}95\% CI, (-0.441)- (-0.419)] for DxI 800 Unicel, Modular E 170, Architect i2000sr and ADVIA Centaur XP, respectively. In our study, all immunoassay analyzers showed poor correlation in a concentration range of TSH between 1.0 to 10.0 uIU/mL and the inverse log/linear relationship was not observed. Inverse relationship between TSH and FT4 is the result of negative thyroid pituitary hypothalamic feedback mechanism and this relationship is important especially in the diagnosis and treatment of hypo and hyperthyroidism. In data sets obtained from four different immunoassay analyzers, poor and statistically different correlation was observed between analyzers at TSH values ranged from 1.0 to 10.0 uIU/mL compared with FT4. Conclusion: These variations between analyzers may affect the clinical decisions especially in the evaluation of subclinical hypothyroidism, clinicians and laboratory specialists should be aware of these situation.Item Macro-aspartate aminotransferase (AST): a case report(WALTER DE GRUYTER GMBH, 2016-01-01) Can, Ummugulsum; Sayar, Ersin; Serdar, Muhittin A.Aspartate aminotransferase (AST) macroenzyme leads to an increase in AST without the presence of any disease. In present report, an isolated increase of AST was detected in a 6-year old girl following the investigations prior to tonsillectomy. As to her history, physical examination and other laboratory test results, no abnormal findings were detected. AST levels were measured as 591 IU/L and 585 IU/L after repeated tests. While found as <5.4 IU/L (recovery <0.8\%, reference interval 42.0-82.2\%) after polyethylene glycol (PEG) precipitation, AST was determined as 561 IU/L (recovery 95.4\%) as a result of the assessment performed with non-specific human antimouse antibodies (HAMA). No diseases were encountered in the patient, and reason for the increase of AST was considered to be macroAST. Because continuously increased enzyme value may lead to various invasive and expensive diagnostic tests, macroAST should be taken into account in the evaluation process.Item What are the predominant parameters for Down's syndrome risk estimation in first- trimester screening: a data mining study(WALTER DE GRUYTER GMBH, 2022-01-01) Kilercik, Mehem; Yozgat, Ihsan; Serdar, Muhittin A.; Aksungar, Fehime; Gogus, Sema; Solak, Semra; Kaya, Zelal Zuhal; Yayla, Ali Murat; Serteser, MustafaObjectives: This study aimed to evaluate the effect size of each parameter used in the first trimester Down Syndrome (DS) risk analyses by using multiple regression analysis techniques. Methods: This data mining study included data of 44,260 pregnant women screened at the Acibadem Labmed laboratories from 2010 to 2019. In this study, risk was calculated using the PRISCA software on the basis of nuchal translucency (NT), crown-rump length measurement, in vitro fertilization application, diabetes mellitus, Down Syndrome story, smoking, maternal age, and the level of maternal serum biochemistry markers including pregnancy-associated plasma protein-A (PAPP-A) and free beta-human chorionic gonadotropin (hCG beta). Results: Forty-four thousand two hundred sixty risk analysis patients result data were re-investigate, and 851 (1.93\%) risk analysis results were found as positive. PAPP-A 747 (CI\%, 476-1,170) times, NT value 512 (CI\%, 343-764) times, DS story 21 times (CI\%, 6.7-63.2) and hCG beta value 7.01 (CI\%, 6.31-7.79) times affect the combined first-trimester risk analysis results. Conclusions: We have suggested that those accurate PAPP-A levels and NT levels evaluation are the most critical point of combined risk analysis and that the risk of free hCG beta levels after PAPP-A is essential as a biochemical test.Item ANALYSIS OF CHANGES IN PARATHYROID HORMONE AND 25 (OH) VITAMIN D LEVELS WITH RESPECT TO AGE, GENDER AND SEASON: A DATA MINING STUDY(SCIENDO, 2017-01-01) Serdar, Muhittin A.; Can, Basar Batu; Kilercik, Meltem; Durer, Zeynep A.; Aksungar, Fehime Benli; Serteser, Mustafa; Coskun, Abdurrahman; Ozpinar, Aysel; Unsal, IbrahimBackground: 25 (OH) vitamin D3 (25(OH) D) and parathyroid hormone (PTH) are important regulators of calcium homeostasis. The aim of this study was to retrospectively determine the cut-off for sufficient 25(OH) D in a four-season region and the influence of age, seasons, and gender on serum 25(OH) D and PTH levels. Methods: Laboratory results of 9890 female and 2723 male individuals aged 38.8 +/- 22.1 years who had simultaneous measurements of 25(OH) D and PTH were retrospectively analyzed by statistical softwares. Serum 25(OH) D and PTH levels were measured by a mass spectrometry method and by an electrochemiluminescence immunoassay, respectively. Results: Mean serum 25(OH) D levels showed a sinusoidal fluctuation throughout the year and were significantly (p < 0.01) higher in summer and autumn. On the other hand, PTH levels were significantly higher (p < 0.01) in women and showed an opposite response to seasonal effects relative to 25(OH) D. Lowest levels of 25(OH) D were detected in people aged between 20 and 40 years whereas PTH hormone levels were gradually increasing in response to aging. The significant exponential inverse relationship that was found between PTH and 25(OH) D (PTH = (exp)(4.12-0.064{*}(sqrt)(25(OH) D)) (r=-0.325, R-squared=0.105, p < 0.001)) suggested that the cut-off for sufficient 25(OH) D should be 75 nmol/L. Conclusions: Our retrospective study based on large data set supports the suitability of the currently accepted clinical cut-off of 75 nmol/L for sufficient 25(OH) D. However, the issue of assessing Vitamin D deficiency remains difficult due to seasonal variations in serum 25(OH) D. Therefore, PTH measurements should complement 25(OH) D results for diagnosing Vitamin D deficiency. It is imperative that seasonally different criteria should be considered in future.