A 6-year-old girl presents with breast development. Her medical history is unremarkable. The parents are of average height, and the mother reports her thelarche was age 11 years. The girl is at the 97th percentile for her height and 90th percentile for her weight. She has Tanner stage 3 breast development and Tanner stage 2 pubic hair development. She has grown slightly more than 3 inches over the past year. How should she be evaluated and managed (N Engl J Med. 2008;358:2366-77)?
The premature onset of puberty, i.e., precocious puberty (PP), can be an emotionally traumatic event for the child and parents. Over the past century, improvements in public health and nutrition, and, more recently, increased obesity, have been associated with earlier puberty and the dominant factor has been attributed to genetics (Curr Opin Endocrinol Diabetes Obes. 2018;25[1]:49-54). This month’s article will focus on understanding what is considered “early” puberty, evaluating for causes, and managing precocious puberty.
Dr. Mark P. Trolice
More commonly seen in girls than boys, PP is defined as the onset of secondary sexual characteristics before age 7.5 years in Black and Hispanic girls, and prior to 8 years in White girls, which is 2-2.5 standard deviations below the average age of pubertal onset in healthy children (J Pediatr Adolesc Gynecol. 2019;32:455-9). As a comparison, PP is diagnosed with onset before age 9 years in boys. For White compared with Black girls, the average timing of thelarche is age 10 vs. 9.5 years, peak growth velocity is age 11.5, menarche is age 12.5 vs. 12, while completion of puberty is near age 14.5 vs. 13.5, respectively (J Pediatr. 1985;107:317). Fortunately, most girls with PP have common variants rather than serious pathology.
Classification: Central (CPP) vs. peripheral (PPP)
CPP is gonadotropin dependent, meaning the hypothalamic-pituitary-ovarian axis (HPO) is prematurely activated resulting in the normal progression of puberty.
PPP is gonadotropin independent, caused by sex steroid secretion from any source – ovaries, adrenal gland, exogenous or ectopic production, e.g., germ-cell tumor. This results in a disordered progression of pubertal milestones.
Whereas CPP is typically isosexual development, i.e., consistent with the child’s gender, PPP can be isosexual or contrasexual, e.g., virilization of girls. A third classification is “benign or nonprogressive pubertal variants” manifesting as isolated premature thelarche or adrenarche.
Causes (see table)
CPP. Idiopathic causes account for 80%-90% of presentations in girls and 25%-80% in boys. Remarkably, international and domestic adoption, as well as a family history of PP increases the likelihood of CPP in girls. Other etiologies include CNS lesions, e.g., hamartomas, which are the most common cause of PP in young children. MRI with contrast has been the traditional mode of diagnosis for CNS tumors, yet the yield is dubious in girls above age 6. Genetic causes are found in only a small percentage of PP cases. Rarely, CPP can result from gonadotropin-secreting tumors because of elevated luteinizing hormone levels.
PPP. As a result of sex steroid secretion, peripheral causes of PPP include ovarian cysts and ovarian tumors that increase circulating estradiol, such as granulosa cell tumors, which would cause isosexual PPP and Sertoli-Leydig cell tumors that secrete testosterone, which can result in contrasexual PPP. Mild congenital adrenal hyperplasia can result in PPP with virilization (contrasexual) and markedly advanced bone age.