ESPE Abstracts

Background: 17-hydroxyprogesterone (17-OHP) basal levels greater than 2ng/ml has been related to the need to request an ACTH test to dismiss non-classic congenital adrenal hyperplasia. We have seen an increase in baseline levels in 2021 compared to 2020.

Objectives: To determine how many of the tests that were requested due to a high basal 17-OHP value, were positive. Assess the need to modify the cut-off points to request an ACTH test. To determine the possible relationship of the increase in basal levels of 17-OHP with the BMI SDS.

Material and Methods: retrospective descriptive study of all patients who underwent an ACTH test between January 1, 2020 and December 31, 2021, in a region of northern Spain. We analyze: sex, age, Tanner stage, BMI SDS, baseline 17-OHP and ACTH test results and main reason for requesting. The test was considered: diagnostic with a peak of 17-OHP at 60 minutes higher than 15 ng/ml, and suggestive if 10-15ng/ml. Laboratory method for the determination of 17-OHP: chemiluminescence immunoassay in Maglumi 2000 Analyzer (Snibe-Diagnostic). The trial meets the quality criteria certified by EQAS QCNet (BioRad-Laboratories, Inc, UK).

Results: 149 ACTH tests were performed, 45 in 2020 and 104 in 2021. 116 women (77.9%). Mean age: 10.1 years (range 2.2-15.9 years). 114 had already started puberty. 21 BMI>2SDS. Main reason for requesting the ACTH test: elevated baseline 17-OHP 38%(20% in 2020, 45% in 2021), accelerated bone age (>2 years)48%, pubarche 9%. Mean baseline 17-OHP was 2.93ng/ml(±3.6ng/ml), median 1.26ng/ml(range 0.1-26ng/ml) in 2020 and 2.67ng/ml(range 0.56-16.2ng/ml) in 2021, difference not statistically significant (P 0.67), but clinically relevant. ACTH test results: mean peak at 60 minutes was 4.98ng/ml(range 0.1-64). The determination of baseline 17-OHP was above 2ng/ml in 61 patients, and above 4ng/ml in 24. But only in 7 cases the test was positive (diagnostic or suggestive), all them with basal 17OHP>4ng/ml. This cut-off point shows a higher specificity with the same sensitivity. Comparing 2020 with 2021, we found no difference in BMI SDS (P 0.27). Relationship between BMI SDS and basal 17OHP was not confirmed (P 0.81).

Conclusions: Our study confirms a significant increase in the number of ACTH tests performed, as well as in the basal level of 17-OHP in the last year. A baseline value of 17-OHP greater than 4ng/dl seems to be the most appropriate as the main indicator of the need to perform the test.