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    Evaluation of optimal urine screening and confirmation cut-off values for opiates, at a national reference laboratory
    (WALTER DE GRUYTER GMBH, 2021-01-01) Karakukcu, Cigdem; Ciraci, Mehmet Zahid; Kocer, Derya; Faydali, Mine Yuce; Serdar, Muhittin Abdulkadir
    Objectives: To obtain optimal immunoassay screening and LC-MS/MS confirmation cut-offs for opiate group tests to reduce false positive (FP) and false negative (FN) rates. Methods: A total of 126 urine samples, -50 opiate screening negative, 76 positive according to the threshold of 300 ng/mL by CEDIA method - were confirmed by a full-validated in-house LC-MS/MS method. Sensitivity, specificity, FP, and FN rates were determined at cut-off concentrations of both 300 and 2,000 ng/mL formorphine and codeine, and 10 ng/mLfor heroinmetabolite 6-mono-acetyl-morphine (6-MAM). Results: All CEDIA opiate negative urine samples were negative for morphine, codeine and 6-MAM. Although sensitivity was 100\% for each cut-off
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    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, Ismail
    Objective: 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.