Verifikacija metode za določanje 1,25-dihidroksi vitamina D v serumu

Varga, Franjo (author), Jerin, Aleš (mentor)

Vitamin D oziroma njegova aktivna oblika ima pomembno vlogo v človeškem telesu. Njegova sinteza je regulirana po potrebah kalcija in fosforja, medtem ko so koncentracije 1,25-dihidroksivitamina D3 spremenjene pri različnih jetrnih in ledvičnih boleznih, boleznih obščitničnih žlez, mutacijah gena za 1α-hidroksilazo, sarkoidozah in limfomih. Zaradi tega je pomembno vedeti, ali je rezultat meritve analita zanesljiv, da mu lahko zaupamo. Cilj naloge je bil preizkusiti lastnosti metode za določanje 1,25-dihidroksivitamina D oziroma preizkusiti natančnost in pravilnost metode za določanje 1,25-dihidroksivitamina D z namenom ugotovitve, ali lahko metodo uporabljamo v rutinskem laboratorijskem delu. Pri določanju koncentracij 1,25-dihidroksivitamina D smo uporabljali set »IDS-iSYSXp«, ki vključuje imunoekstrakcijo 1,25-dihidroksivitamina D, in aparat »IDS-iSYS Multi-Discipline Automated System«. Natančnost smo določali s pomočjo modela 5 × 5, ki vključuje 5 meritev v 5 dneh. Kriterije sprejemljivosti lahko navaja proizvajalec, ali so navedeni v Westgardovi bazi podatkov bioloških variacij. V današnjem pristopu kontrole kakovosti v laboratoriju se upoštevajo potrebe klinikov, pri čemer so meje nenatančnosti postavljene glede na biološko variacijo. Pri preizkušanju natančnosti med serijami in znotraj njih smo dobili koeficiente variacij pod 10 %, kar zadošča kriterijem sprejemljivosti. Pravilnost smo določali z merjenjem vzorcev iz programa za zunanjo kontrolo kakovosti, ki nam kaže, za koliko rezultat odstopa od prave vrednosti, in se običajno označuje kot netočnost. Ocenjevanje točnosti s pomočjo vzorcev za zunanjo kontrolo kakovosti smo uporabljali iz tehničnih razlogov, ker smo imeli že zbrane in obdelane podatke zunanjih kontrol. Program za zunanjo kontrolo vitamina D navaja, da mora biti več kot 80 % rezultatov zunanjih kontrolnih vzorcev znotraj 30 % tarčne vrednosti. Rezultati, ki smo jih dobili pri merjenju zunanjih kontrol, zadoščajo kriterijem, ki jih navaja program za zunanjo kontrolo vitamina D. Z verifikacijo metode smo dobili rezultate znotraj kriterijev sprejemljivosti in zaradi tega lahko zaključimo, da je metoda ustrezna za rutinsko laboratorijsko prakso.

• Language: Slovenian
• Keywords: vitamin D, natančnost, pravilnost, verifikacija
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2020
• PID: 20.500.12556/RUL-116494
• Publication date in RUL: 26.05.2020

Secondary language

• Language: English
• Title: Method verification for determining 1,25-dihydroxyvitamin in serum

Abstract

Vitamin D has an important role in human body. Synthesis depends on body sources of phosporus and calcium. 1,25-dihydroxyvitamin D3 concentrations are altered with variety of hepatic and renal diseases, as well as with disorders of parathyreoid gland, 1 α hydroxylase mutations, sarcoidosis and lymphoma. Therefore, it is important to specify the result to make it thrustworthy diagnostic method. Aim of this research was to analyze the characteristics of 1,25-dihydroxyvitamin D quantifying method, as well as to determine the precision and accuracy for the purpose of using this method in routine laboratory practise. For determinating concentations of 1,25-dihydroxyvitamin D we used „IDS-iSYSXp“ kit wich includes imunoextraction of 1,25-dihydroxyvitamin D and the machine „IDS- iSYS Multi-Discipline Automated System“. 5 × 5 experimental model was used to determine the precision. The model is conducted from five measurements in five days. Acceptance criteria are defined by the manufacturer of the method or by the Westgard database of desirable biological variations. Modern approach to quality control follows the needs of clinicians; therefore the limits of imprecision are set in reference to biological variations. Coefficiets of variations for within a between series precision were all under 10 % wich satisfies acceptance criteria. Accuracy was determinated with measurements of samples from external quality assessment program. Accuracy is a measure which gives us information of how much the result is deviating from real value, and is expressed as inaccuracy. We used external quality assessment samples for technical reasons because we already had the results from external quality assessment organizers. From examinating the results of method verification we concluded that the results are within the acceptance criteria, and that the method can be used in routine laboratory practise. External quality assessment program for Vitamin D quotes that more than 80% of the results of external control samples must be within 30 % of the target value. Our results satisfied external quality assessment program for Vitamin D demands.

• Keywords: vitamin D, precision, accuracy, verification