ESPE Abstracts

Introduction: In children, estradiol (E2) concentrations are 1000-times lower in comparison to their precursors, the androgens. Depending on sex, age, and pathology, plasma concentrations vary in a broad range. The sensitive and specific determination of E2 is a particular challenge in pediatric endocrinology. Here we report a female patient aged 12 6/12 years and Tanner stage B1 with a presumed diagnosis of ovarian insufficiency. She showed a very high E2 concentration of 296 pmol/l fitting with the age reference (ref. 10-430 pmol/l, 12-14 years) but not with the clinical diagnosis and Tanner B1. The aim of our study was to identify possible interfering factors.

Methods: First, E2 was determined by LC-MS/MS. Secondly, two new blood samples of the patient were collected independently in two different types of monovettes. One monovette was the same used beforehand (Kabe Labortechnik) and the other one typically preferred by our pediatric laboratory (Sarstedt). In a third approach, monovettes were broken down into their components (gel, pellets, and hole monovette). The components were incubated independently with either aqua dest. or strip-plasma for one week.

Results: On average, ten times higher E2 concentrations were determined in the patient using the Kabe monovette (average: 147.94 pmol/l, SD: 81.57, n = 5) compared with the Sarstedt monovette (average: 15.13 pmol/l, SD: 6,86, n = 3). Further on, an unusual broad peak was noticed at the typical position of the E2 peak using the Kabe monovettes. After incubating each component of the monovettes, a similar wide peak could be identified after incubation with the gel of the Kabe monovette. Possible isomeric interference could be excluded by chromatographic separation of 17-α and 17-β-E2 into two separated peaks.

Conclusion: In addition to classic interfering factors like lipemia and haemolysis, monovettes are pre-analytical factors which need to be considered in the sensitive analysis of E2 via LC-MS/MS. Therefore, automated evaluation should not be used for E2 determination in LC-MS/MS. Paediatric hormonal measurements should involve pediatric endocrine validation to notice discrepancies.