Browsing by Author "Yucel, Dogan"

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A short guideline on chronic kidney disease for medical laboratory practice
(WALTER DE GRUYTER GMBH, 2016-01-01) Abusoglu, Sedat; Aydin, Ilknur; Bakar, Funda; Bekdemir, Tan; Gulbahar, Ozlem; Islekel, Huray; Ozarda, Yesim; Pektas, Macit; Pir, Kamil; Portakal, Oytun; Serdar, Muhittin; Turhan, Turan; Yucel, Dogan; Zengi, Oguzhan
Chronic kidney disease (CKD) is asymptomatic in the early stage. Kidney function might be lost 90\% when the symptoms are overt. However, in case of early detection, progression of the disease can be prevented or delayed. If not detected it results in end stage renal disease. Therefore, the level of awareness about CKD should be increased. The role of medical laboratory is utmost important for the diagnosis and staging of CKD. In this paper, the main tasks of the laboratory specialists are described and the outlines are as follows. Creatinine assays should be traceable to internationally recognised reference materials and methods, specifically isotope dilution mass spectrometry. When reporting the creatinine result, eGFR should also be reported in adult (> 18 years) population. A warning expression should be included in the report form if eGFR result is <60 mL/min/1.73 m(2). eGFR values should be expressed quantitatively up to 90 mL/min/1.73 m(2) by CKD-EPI equation. Above 90 mL/min/1.73 m(2), eGFR values can be expressed quantitatively or >90 mL/min/1.73 m2. eGFR equations of the adult population should not be used for pediatric population. Different equations utilizing also patient height should be used. The enzymatic creatinine assay should be preferred. eGFR based on cystatin C can be used for confirmation in the pediatric population. Cystatin C measurements, at least when eGFR based on creatinine is not reliable and for confirmation should be encouraged. Proteinuria or albuminuria values should be measured in spot samples and reported in proportion to creatinine.
COVID-19 laboratory biosafety guide
(WALTER DE GRUYTER GMBH, 2020-01-01) Zengi, Oguzhan; Aykal, Guzin; Coskun, Cihan; Serdar, Muhittin; Yucel, Dogan
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, Dogan
Objective: 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\%)
Sample size, power and effect size revisited: simplified and practical approaches in pre-clinical, clinical and laboratory studies
(CROATIAN SOC MEDICAL BIOCHEMISTRY \& LABORATORY MEDICINE, 2021-01-01) Serdar, Ceyhan Ceran; Cihan, Murat; Yucel, Dogan; Serdar, Muhittin A.
Calculating the sample size in scientific studies is one of the critical issues as regards the scientific contribution of the study. The sample size critically affects the hypothesis and the study design, and there is no straightforward way of calculating the effective sample size for reaching an accurate conclusion. Use of a statistically incorrect sample size may lead to inadequate results in both clinical and laboratory studies as well as resulting in time loss, cost, and ethical problems. This review holds two main aims. The first aim is to explain the importance of sample size and its relationship to effect size (ES) and statistical significance. The second aim is to assist researchers planning to perform sample size estimations by suggesting and elucidating available alternative software, guidelines and references that will serve different scientific purposes.
Utilization of biological variation data in the interpretation of laboratory test results - survey about clinicians' opinion and knowledge
(CROATIAN SOC MEDICAL BIOCHEMISTRY \& LABORATORY MEDICINE, 2021-01-01) Emre, Humeyra Ozturk; Karpuzoglu, Fatma Hande; Coskun, Cihan; Sezer, Ebru Demirel; Ozturk, Ozlem Goruroglu; Ucar, Fatma; Cubukcu, Hikmet Can; Arslan, Fatma Demet; Deniz, Levent; Senes, Mehmet; Serteser, Mustafa; Yazici, Cevat; Yucel, Dogan; Coskun, Abdurrahman
Introduction: To interpret test results correctly, understanding of the variations that affect test results is essential. The aim of this study is: 1) to evaluate the clinicians' knowledge and opinion concerning biological variation (BV), and 2) to investigate if clinicians use BV in the interpretation of test results. Materials and methods: This study uses a questionnaire comprising open-ended and close-ended questions. Questions were selected from the real-life numerical examples of interpretation of test results, the knowledge about main sources of variations in laboratories and the opinion of clinicians on BV. A total of 399 clinicians were interviewed, and the answers were evaluated using a scoring system ranked from A (clinician has the highest level of knowledge and the ability of using BV data) to D (clinician has no knowledge about variations in laboratory). The results were presented as number (N) and percentage (\%). Results: Altogether, 60.4\% of clinicians have knowledge of pre-analytical and analytical variations