Among girls with true central precocious puberty (CPP) referred to a tertiary center in Israel, nonclassical congenital adrenal hyperplasia (CAH) was diagnosed in almost 5% of patients, according to study results published in The Journal of Clinical Endocrinology & Metabolism.

Most cases of true CPP are idiopathic, but the condition can also be secondary to the classic or nonclassic forms of congenital adrenal hyperplasia. In the Israeli population, the prevalence of nonclassical CAH is 10 times higher than in the general world population, and for that reason, there is a higher chance that girls with CPP in Israel have nonclassical CAH. In this study, researchers aimed to determine the prevalence of nonclassical CAH in girls with CPP and identify characteristics that could assist in distinguishing idiopathic CPP and CPP secondary to nonclassical CAH.

The retrospective study was based on a database of a tertiary endocrinology institute. The cohort included 2 groups: 140 girls who presented with idiopathic CPP between 2008 and 2017 and 37 girls with CPP and nonclassical CAH, including 7 girls who presented with CPP from 2008 to 2017 and 30 girls who presented between 1984 and 2008. Demographic, anthropometric, clinical, and laboratory data were compared between the groups.

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Nonclassical CAH was found to be the cause of CPP in 4.8% of the 147 girls who presented with CPP at the clinic between 2008 and 2017. There were no significant differences between the group of patients with idiopathic CPP and those with CPP and nonclassical CAH in terms of height, weight, body mass index, maternal age at menarche, birth weight, gestational age, or bone age.

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Mean basal androgen levels were significantly higher in the group of patients with nonclassical CAH compared with girls with idiopathic CPP: androstenedione (5.01 vs 2.15 nmol/L; P <.001), 17-hydroxyprogesterone (32.62 vs 1.86 nmol/L; P <.001), and dehydroepiandrosterone (30.6 vs 1.5 nmol/L; P <.001). However, as there was a significant overlap between the groups’ ranges, these androgens were not accurate diagnostic markers.

According to the researchers, the inclusion of girls diagnosed with nonclassical CAH before 2008 was a possible limitation of the study; although laboratory tests have not changed over the years, it is possible that secular trends influenced the results.

“The high prevalence of [nonclassical CAH] and the lack of even one parameter that was diagnostic for [nonclassical CAH] suggest that the evaluation of girls presenting with ‘idiopathic’ CPP should include basal androgens,” concluded the researchers.

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Neeman B, Bello R, Lazar L, Phillip M, de Vries L. Central precocious puberty as presenting sign of non-classical congenital adrenal hyperplasia – clinical characteristics [published online February 19, 2019]. J Clin Endocrinol Metab. doi:10.1210/jc.2018-02605