Background: Although peripheral precocious puberty has been reported due to untreated long-standing hypothyroidism in children with Down syndrome (DS), central precocious puberty (CPP) has been scarcely reported. The aim of this study is to describe our experience with this rare condition. Case presentation: Three patients (two males and one female) who were receiving treatment for hypothyroidism and admitted with signs of precocious puberty were recruited in the study. Clinical and laboratory findings were compatible with CPP in all three patients with DS. They were euthyroid during investigations for CPP. A male patient had periventricular millimetric focuses in the supratentorial region in cranial magnetic resonance imaging. The other male patient developed central adrenal insufficiency during fallow-up and hence hydrocortisone was added to the treatment. All patients were successfully treated with gonadotropinreleasing hormone analogs; no adverse effects have been observed. Conclusion: Our findings emphasize that CPP might be seen in rare cases with DS and hypothyroidism.

Keywords: Down syndrome, central precocious puberty, hypothyroidism, leuprolide acetate, case reports