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Trape J.,Service of Clinical Chemistry | Montesinos J.,Service of Oncology | Franquesa J.,Service of Clinical Chemistry | Sala M.,Service of Clinical Chemistry | And 3 more authors.
Clinical Chemistry and Laboratory Medicine | Year: 2012

Background: Biological variation is important for determining analytical goals and for establishing the magnitude of change between two consecutive measurements. The aim of this study was to determine the biological variation for S100 β and lactate dehydrogenase in patients diagnosed with malignant melanoma but without evidence of disease recurrence. Methods: The biological variation of S100 β and lactate dehydrogenase was estimated from a mean of four consecutive measurements in 32 patients diagnosed with malignant melanoma but without evidence of disease recurrence, 3 months after tumor resection or 4 months after finish-ing adjuvant treatment. The mean sampling interval was 3 months. Results: Mean concentrations of S100 β and lactate dehy-drogenase were 0.0557 μ g/L and 6.3 μkat/L, respectively. Between-run analytical variation was 3.5 % at 0.181 μg/L for S100 β and 3.5 % at 2.83 μ kat/L for lactate dehydrogenase. Biological variations obtained for S100 β and lactate dehy-drogenase were 14.2 % and 8.2 %, respectively. The analytical goals (defined as 50 % of biological variation) were 7.1 % for S100 β and 4.1 % for lactate dehydrogenase. Conclusions: The estimation of biological variation allows us to calculate analytical goals and reference change values. These are necessary tools for the correct interpretation of serial measurements in patient follow-up. © 2012 by Walter de Gruyter •Berlin • Boston. Source


Trape J.,Service of Clinical Chemistry | Franquesa J.,Service of Clinical Chemistry | Sala M.,Service of Clinical Chemistry | Domenech M.,Service of Oncology | And 8 more authors.
Clinical Chemistry and Laboratory Medicine | Year: 2010

Background: Knowledge of biological variation (BV) is important for determining analytical goals and for establishing the magnitude of change between two consecutive measurements which indicate change in a patients' health status. The aim of this work is to determine the BV for total choriogonadotropin (β chain) (β-hCG) and α-fetoprotein (AFP) in patients diagnosed with testicular cancer but with no evidence of recurrence of disease. Methods: We estimated BV from a mean of five consecutive measurements in 28 patients diagnosed with testicular cancer, 3 months after tumor resection or 4 months after complete treatment with chemotherapy. The mean sampling interval was 3 months. Results: The mean concentrations of α-fetoprotein and choriogonadotropin (β chain) were 3.9 μg/L and 0.79 IU/L, respectively. Between-run analytical variation was 7.1% at 4.1 μg/L for α-fetoprotein, and 19% at 0.65 IU/L for choriogonadotropin (β chain). BV obtained for α-fetoprotein and choriogonadotropin (β chain) was 12.4% and 16.7%, respectively, and the reference change value (RCV) for one-tail showed 38.2% and 60.7% for α-fetoprotein and choriogonadotropin (β chain), respectively. Conclusions: The estimation of BV allows us to calculate analytical goals and RCVs, necessary tools for the correct interpretation of serial measurements in the follow-up of patients. © 2010 by Walter de Gruyter Berlin New York. Source

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