New LC-MS/MS reference data for estradiol show mini-puberty in both sexes and typical pre-pubertal and pubertal patterns.

CONTEXT:Reliable estradiol (E2) reference intervals (RIs) are crucial in Pediatric Endocrinology. OBJECTIVES:To develop a sensitive ultra-performance liquid chromatographic tandem mass spectrometry (UPLC-MS/MS) method for E2 in serum, to establish graphically represented RI percentiles and annual RIs for both sexes and to perform a systematic literature comparison. METHODS:First, an UPLC-MS/MS method for E2 was developed. Second, graphically represented RI percentiles and annual RIs covering 0-18 years were computed (cohort of healthy children (1181 girls, 543 boys)). Subsequently, RIs were compared with published data by systematic searches. RESULTS:Lower limit of quantification was 11 pmol/L, indicating high sensitivity. E2 first peaked during mini-puberty in both sexes (girls up to 192 pmol/L; boys up to: 225 pmol/L). As could be expected, girls showed higher pubertal E2 (up to 638 pmol/L). However, boys' RIs (up to 259 pmol/L) overlapped considerably. We found four studies in the literature which also used LC-MS/MS to determine E2 and published RIs for the complete pediatric age range. RIs varied considerably. Pre-pubertal and pubertal phases were present in all studies. Higher E2 during the time of mini-puberty in both sexes was documented in three studies including ours. CONCLUSIONS:Variability of RIs for E2 between studies illustrates importance of laboratory-specific RIs despite using a liquid chromatographic tandem mass spectrometry (LC-MS/MS) reference method. In boys, the striking E2 peak during mini-puberty as well as high pubertal E2 without phenotypic estrogenization in regular male puberty indicate that the role of E2 in children, and especially in boys requires better functional understanding.