Introduction: The diagnosis of Congenital Adrenal Hyperplasia (CAH) is a challenge due to the complexity of its pathophysiology and the variety of clinical manifestations. Female newborns (NB) with classical forms present virilization of the external genitalia while in boys it is usually normal. Salt-losers boys and girls are highly susceptible to develop acute adrenal insufficiency and death in the first weeks of life; for these reasons, Neonatal Screening (NS) programs have included CAH among the diseases surveyed. In the State of Parana, Brazil, NS for CAH started in 2013.
Objectives: To determine the prevalence of CAH in Parana; to characterize interfering factors related to false positive results for CAH; and to determine sensitivity, specificity, accuracy, positive and negative predictive values and false positive rate of the 17-OHP dosing method.
Patients and methods: Clinical and laboratorial evaluation of NB tested positive for CAH in the period of August/2013-July/2016; 17-OHP in blood spot was measured by immunofluorymetric assay and in serum by either RIA or ELISA. NB were followed at the Pediatric Endocrinology Unit of the Department of Pediatrics of the Federal University of Paraná School Hospital.
Results and conclusions: Of 474,890 NB in the period, 475 tested positive for CAH; of those, 403 were evaluated and 392 were included in the study; of these 369 (94.1%) were false positive, while 23 (5.9%) had confirmed CAH. Among the 23, twenty-one are salt-losers, the other two with simple virilizing and non-classical forms, respectively. Prevalence of the classical form of CAH in the period is 1:21,596 live births, with higher prevalence in the west and southwest regions of the state. The female to male ratio was 1.4:1.0. Prematurity and neonatal stress were related to false positive screening. Sensitivity of the 17-OHP method for filter paper was 100%; specificity and accuracy were 99.9%; the positive predictive value was 5.1%; the negative predictive value was 100%; the recall rate was 0.99% and the false positive rate 0.08%. There are challenges in the program: to standardize the method to measure serum 17OHP, to minimize errors in the collection of the blood spot and to provide adequate treatment to all children with CAH.
27 - 29 Sep 2018
European Society for Paediatric Endocrinology