Tamara van Donge

Chapter 10 208 Table 4: Predicted mean values and 95% confidence intervals based on the fitted linear or piecewise regression models for eight kidney biomarkers, with age treated as a continuous variable. a for cystatin C, a breakpoint of 1.5 years was used. 2 years a 5 years 10 years 15 years All ages (0 – 15 years) Age dependent kidney biomarkers ALB, g/L 36.9 [28.7 – 45.1] 37.6 [29.4 – 45.8] 38.8 [30.6 – 47.0] 40.0 [31.8 – 48.2] na B2M, mg/L 1.9 [1.3 – 2.5] 1.7 [1.1 – 2.3] 1.6 [1.0 – 2.1] 1.7 [1.1 – 2.3] na BTP, mg/L 0.9 [0.6 – 1.1] 0.7 [0.5 – 1.0] 0.6 [0.4 – 0.9] 0.6 [0.4 – 0.9] na SCR, µmol/L 22.7 [15.2 – 33.9] 28.3 [18.9 – 42.3] 40.8 [27.3 – 61.0] 58.9 [39.4 – 88.1] na KIM-1, ng/L 1319.4 [88.4 – 19684] 1091.2 [73.1 - 16278] 795.1 [53.3 - 11861] 579.3 [38.8 - 8642] na CYSC, mg/L Boys 1.06 [0.71 – 1.22] 0.89 [0.64 – 1.16] 0.91 [0.65 – 1.17] 0.93 [0.67 – 1.19] na Girls 0.91 [0.66 – 1.17] 0.85 [0.60 – 1.11] 0.87 [0.61 – 1.13] 0.89 [0.63 – 1.14] na Age independent kidney biomarkers NGAL, µg/L na na na na 40.0 [1.4 – 78.6] URO, µg/L na na na na 146.0 [17.4 – 274.4] Discussion This prospective study provides references intervals for eight endogenous serum kidney function and injury markers, reflecting normal kidney function in 142 healthy infants, children and adolescents. Six markers showed age-dependency (ALB, SCR, B2M, BTP, CYSC and KIM- 1), whereas the other two markers (NGAL and URO) did not show any association with age. In terms of defining reference intervals for the whole pediatric age range (0 to ≤ 15 years), the sample size for each marker, except KIM-1, is in accordance with the recommendations of the CLSI, which recommends a minimum of 120 individuals. 23,26 No relevant nephrotoxic drug exposure was reported, only 2% of participants were exposed to medication