MC cause of precocious puberty is -

Ans. is 'a' i.e., Constitutional * Most common cause of precocious puberty is constitutional/idiopathic.* Puberty before the age of 8 years in girls or 9 years in boys is considered precocious puberty. Menarche before the age of 10 years in girls is also considered as precocious.* Precocious puberty is of two types1. Central or true precocious puberty# Results from excessive GnRH, gonadotropins and target sex hormone elaborated by premature activation of hypothlamic pituitary-gonadal (HPG) axis.2. Peripheral or pseudo-precocious puberty# Due to increased sex steroid secretion from either the adrenal gland or the gonadsfDNB l5).# It is independent of HPG axis activation Causes of Precocious pubertyA.Central precocious puberty 1. Idiopathic: Sporadic or familial.2. Central nervous system abnormalitiesi) Congenital anomalies of CNS: Hypothalamic hamartoma, hydrocephalus, porencephaly, arachnoid cysts.ii) Acquired lesions of CNS: Inflammation, granuloma, trauma, surgery, radiation, chemotherapy.iii) Tumors of CNS: Pineal tumors, optic glioma, ependymoma, carniopharyngioma.iv) HypothyroidismB.Peripheral precocious puberty: Isosexual Girls 1. Ovarian causes: McCune-Albright syndrome, benign follicular cysts, granulosa-theca cell tumors; Gonado- blastoma.2. Adrenal causes: Feminizing adrenal neoplasia3. Exogenous estrogen administration Boys 1. Testis: Leydig cell tumor, adrenal rest tumor, testotoxicosis.2. Adrenal: CAH (21 or 11-$ hydroxylase deficiency), virilizing tumors.3. hCG secreting tumors: Hepatoma, hepatoblastoma, choriocarcinoma, chorionepithelioma, teratoma, dysgerminoma.4. Exogenous testosteroneC.Heterosexual precocity 1. Girls: Virilization in girls due to virilizing CAH, ovarian or adrenal neoplasia, polycystic ovarian disease.2. Boys: Feminization due to estogen producing adrenal tumors, exogenous estrogen, marijuana smoking.Note: Hypothyroidism usually causes delayed puberty, but juvenile hypothyroidism some times can cause precocious puberty.