Endocrine Abstracts

Introduction: The major clinical importance of 17-OH-Progesterone is related to the diagnosis and therapeutic monitoring of Congenital Adrenal Hyperplasia (CAH). Radioactive assays are widely used in clinical laboratories for measuring 17-OH-Progesterone. The appearance of a non-isotopic, chemiluminescent automatic assay, may be an interesting alternative if the performance of the assay remains the same or higher.

Obective: To compare the 17-OH-Progesterone results by a radioimmunoassay (RIA) and a chemiluminescent assay (CLIA) and to analyze the clinical impact taking into account the % concordance.

Material and methods: We studied 74 patients, aged 6 months to 83 years old, observed at CHLC endocrinology appointments, in Lisbon. The serum samples were analyzed by ‘17α-Hydroxyprogesterone (17-OHP)-RIA-CT’, DIASource (wr: 0.04–12.5 ng/ml) and ‘Maglumi 17-OH Progesterone (CLIA)’ Snibe (wr: 0.1–20 ng/ml). An excel tool was used for statistical treatment and the clinical concordance of patients was analyzed according to the reference values of both. For statistical comparison nine patients were excluded and to analyze the clinical impact we divided patients into groups according to age and gender.

Results: Pearson correlation coefficient r=0.90 and the equation of linear regression was:y=0.46x+0.17. Group 1=24 both gender (6m-11y); Group 2: 12 male (12 y-47y); Group 3: 38 female (13y–83y). For the group 1 and 2: % agreement was 62.5 and 66; It was impossible to classified 25% of group 1 because CLIA has no reference values for age. Group 3 had insufficient clinical data.

Conclusion: There is a good correlation but in order to become an alternative to RIA it is fundamental to have reference values between 3 months and 3 years for a further reassessment since its main usefulness is the diagnosis and monitoring of CAH.