Встановлення референтних значень концентрації сукцинілацетону в сухих плямах крові дітей

Abstract

В даному дослідженні було визначено концентрацію сукцинілацетону в сухих плямах крові 149 дітей з різних регіонів України віком від 7 днів до 18 років методом тандемної мас-спектрометрії. В результаті проведеного дослідження було показано, що не існує статистично достовірної різниці між концентрацією сукцинілацетону у вікових вибірках дітей та вибірках по статі, за критерієм Манна-Уїтні p>0,05. В ході роботи було отримано наступні референтні значення 0,77 та 3,87 мкмоль/л, які відповідали 2,5 та 97,5 персентилю відповідно. На основі отриманих референтних значень можна стверджувати, що концентрація сукцинілацетону в сухих плямах крові у пацієнтів з тирозинемією відрізняється в 2-4 рази від верхньої межі референтного інтервалу (РІ), а у пацієнтів з галактоземією в більшості випадків знаходиться на верхній межі РІ; В данном исследовании были проанализированы сухие пятна крови 149 детей из разных регионов Украины в возрасте от 7 дней до 18 лет методом тандемной масс-спектрометрии. В результате проведенного исследования было показано, что не существует статистически достоверной разницы между концентрацией сукцинилацетона в возрастных выборках детей и выборках по полу, по критерию Манна-Уитни p>0,05. В ходе работы были получены следующие референтные значения 0,77 и 3,87 мкмоль/л, соответствующие 2,5 и 97,5 персентилям соответственно. На основе полученных референтных значений можно утверждать, что концентрация сукцинилацетона в сухих пятнах крови у пациентов с тирозинемией отличается в 2-4 раза от верхней границы референтного интервала (РИ), а у пациентов с галактоземией в большинстве случаев находится на верхней границе РИ; Succinylacetone is an intermediate metabolite of tyrosine and specific biochemical marker for inherited metabolic disorder tyrosinemia type 1. The fastest and the most convenient method for succinylacetone determination in dry blood spots is a method of tandem mass spectrometry, which is used in developed countries for mass neonatal screening of tyrosinemia type 1. For accurate interpretation of tests results it is necessary to use reference values that match the ethnic characteristics of the population, preanalytic and analytic phases of the diagnostics. Most of all available reference values in publications are incomplete because they are set for a specific gender or age. Therefore, it is important to define your own reference values that will match to your method peculiarities and ethnicity. Purpose of the study. Determination of succinylacetone concentration reference values in dry blood spots of children aged from 7 days to 18 years in Ukraine. Results and discussion. First of all in this paper was hold partition of the total number of children (150 people) into the age groups (30 people): 0-2 months, 2 months, 1 year, 1-5 years, 5-10 years and 10-18 years according to the recommendations of the International Federation of Clinical Chemistry (IFCC) and the Institute for Clinical and Laboratory Standards (CLSI). Succinylacetone values in dry blood spots of all age groups were tested for normality by the Shapiro-Wilk criterion, and it was found that distribution in all groups is not consistent with Gaussian distribution. When compared succinylacetone concentration values in these groups by Mann-Whitney, it was determined that there are no statistically significant differences between all groups (p>0.05). After that we separate total number of children into two groups by gender. In our study was shown that between girls and boys there was no statistically significant difference by Mann-Whitney. According to such results it was decided to combine all the data into one group, which consisted of 149 people. Check for normality of combined data was made by Shapiro-Wilk criterion and showed that the distribution of the sample is not normal, p<0,0001. So it allowed to count the median – 1,81 μmol/l and 2,5 and 97,5 persentiles — 0,77 and 3,87 μmol/l that outline the limits with 95% confidence. Comparing the results with the available publications it is obvious that reference intervals and cutoff values of different authors are significantly different. Such differences in reference values can be related to the peculiarities of the method of analysis, preparation, and storage of material and calculations of the results. Reference values of succinylacetone concentration in dry blood spots of Ukrainian children which were determined in our study we observed the significant 2 times difference, and in some cases 10 times from reference values mentioned in the literature. Increase of succinylacetone concentration in dry blood spots confirms the diagnosis tyrosinemia type 1. If we take into account the reference values calculated by us, the succinylacetone concentration of three patients with tyrosinemia type 1 that were previously examined in the laboratory of medical genetics NDSL «OKHMATDYT» showed 2-4 times increase. And in two children with galactosemia was observed a slight increase of the level or was close to the upper limit of succinylacetone reference values. Conclusions. In this study succinylacetone concentration was determined in dry blood spots of 149 children from different regions of Ukraine aged from 7 days to 18 years by tandem mass spectrometry. As a result was shown that there was no statistically significant difference between the succinylacetone concentration in the age and gender groups of children by the Mann-Whitney criteria p>0,05. During the research were received the following reference values of 0,77 μmol/l and 3,87 μmol/l, which corresponded to 2,5 and 97,5 percentiles respectively. Based on the determined reference values we could affirm that succinylacetone concentration in dry blood spots of patients with tyrosinemia type 1 2-4 times exceeds the upper limit of the reference interval (RI), and in patients with galactosemia in most cases is at the upper limit of RI.