The Use of Routine Laboratory 17‐Hydroxyprogesterone for Identification of Cases of 21‐Hydroxylase Deficiency Congenital Adrenal Hyperplasia

Background Clinical outcome studies of 21‐hydroxylase deficiency congenital adrenal hyperplasia (21OHD CAH) may be subject to selection bias due to incomplete case ascertainment. This study aimed to develop a methodology for identifying existing CAH cases and explore its utility to study clinical outcomes. Methods 17‐hydroxyprogesterone assays (17OHP) processed in NHS Greater Glasgow and Clyde between 2014 and 2022 were analysed based on 17OHP result (≥ 6 or < 6nmol/L), location, test frequency and clinical details. Identified cases were cross‐referenced against local clinical data logs. For confirmed cases, current age, sex, age at diagnosis, mortality status, most recent blood pressure (BP) and anthropometry were collected. Results Assay results from 57,011 cases were extracted and, of these, 116 (F:M, 81:35) had confirmed CAH but 66 (57%) were not reported by any local clinical data logs. The median age at the time of the study was 33 years (range, 2, 75) and 95 (82%) were over 16 years (F:M, 69:26). In these adults, 52 (55%) were diagnosed in childhood (i.e. ≤ 16 years) and only 1 male was diagnosed in adulthood. The median body mass index (BMI) standard deviation score of children was 0.70 (−2.43, 3.15). Median BMI of adults was 28 (15, 56) and median adult and paediatric systolic BP was 120 mmHg (95, 153) and 106 mmHg (83, 130), respectively. Conclusion The 17OHP‐based algorithm that was used in this study represents a useful method for identifying existing cases of CAH and can allow improved understanding of routinely collected markers of clinical outcome.