Intervalli di riferimento standardizzati della fosfatasi alcalina sierica in soggetti pediatrici

Traceable reference intervals for alkaline phosphatase in serum of pediatrics. The definition of pediatric reference intervals for alkaline phosphatase (ALP) in serum represents a challenging task due to the high and variable concentrations of this enzyme in children compared to adults. Aim of this work was the establishment of ALP pediatric reference intervals in an Italian population using an indirect method and traceable assays for ALP measurements. A data mining approach involving 12 centers was applied. To verify the analytical quality of the participating centers, 3 pools with ALP target values established by the reference procedure were distributed and analyzed by the centers at the beginning and at regular intervals during the data collection period (May-September 2016). When needed (deviation from target >2%), the results obtained on the 3 pools were used to recalculate ALP results of reference individuals, thus making them traceable to the reference procedure. Each center selected from its database the ALP results of outpatients, aged 0-20 years, excluding those from oncological or orthopedic clinics and the results from subjects that repeated the test more than once. Very high and very low ALP values were investigated for excluding liver, kidney or bone disease. The results were elaborated with a modification of the algorithm proposed by Concordet et al. 4824 ALP values were collected (2372 from females and 2452 from males, respectively). The lower reference limit was the same for boys and girls <12 years old (140 U/L), reaching down the adult concentrations at 16 years for females and 18 years for males. The pubertal peak was at 9-11 years for females (430 U/L) and 12-14 years for males (465 U/L).