Browsing by Author "Ispir, Emre"

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    A Simple Method for Quantification of Five Urinary Porphyrins, Porphobilinogen and 5-Aminolevulinic Acid, Using Liquid Chromatography Tandem Mass Spectrometry
    (SPRINGER INDIA, 2019-01-01) Dogan, Ozlem; Serdar, Muhittin A.; Murat, Koza; Sonmez, Cigdem; Ispir, Emre; Serteser, Mustafa; Unsal, Ibrahim
    Analysis of porphyrins and 5-aminolevulinic acid (ALA), porphobilinogen (PBG) in physiological liquids is required for diagnosis and follow-up of porphyrias. High performance liquid chromatography (HPLC) and liquid chromatography tandem mass spectrometry (LC-MS) methods with higher specificity and sensitivity have been developed. The major disadvantage of those methods is that they require longer extraction times due to their matrix effects. The present study suggests a simple, fast, sensitive, and specific assay for determination of Coproporphyrin, 5-carboxylporphyrin, 6-carboxylporphyrin, 7-carboxylporphyrin, Uroporphyrin I and ALA, PBG in urine sample by direct injection without sample pre-treatment using LC-MS. For the purposes of the present study LC-MS device was set to multiple reaction monitoring (MRM) and positive ion mode. Porphyrins and ALA, porphobilinogen were characterized by their MS/MS product ion, spectra. ALA, PBG and 5 porphyrins were detected simultaneously. Limit of detection for Coproporphyrin, 5-carboxylporphyrin, 6-carboxylporphyrin, 7-carboxylporphyrin, Uroporphyrin I were 2nmol/L, where it was 5mol/L for ALA and 2mol/L for porphobilinogen. The present study suggests that the present method is very effective compared to many other available methods for it does not require pre-treatment, provides simultaneous results of ALA, PBG and 5 porphyrins quantitatively in a shorter span of time, and has suitable sensitivity and selectivity. LC-MS technique was used clinically for the determination of urine porphyrin levels.
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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.