Precocious Puberty Clinical Presentation

Updated: Jan 24, 2022
  • Author: Paul B Kaplowitz, MD, PhD; Chief Editor: Robert P Hoffman, MD  more...
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Precocious puberty in girls

The first and most obvious sign of early puberty is usually breast enlargement, which may initially be unilateral.

Pubic and axillary hair may appear before, at about the same time as, or well after the appearance of breast tissue. Axillary odor usually starts about the same time as the appearance of pubic hair.

Menarche is a late event and does not usually occur until 2-3 years after the onset of breast enlargement.

The pubertal growth spurt occurs early in female puberty and usually is evident by the time of initial evaluation.

Precocious puberty in boys

The earliest evidence of puberty is testicular enlargement, a subtle finding that often goes unnoticed by patients and parents.

Growth of the penis and scrotum typically occurs at least a year after testicular enlargement.

Accelerated linear growth (the pubertal growth spurt) occurs later in the course of male puberty than in female puberty but often takes place by the time other physical changes are noted.



Precocious puberty in girls

The most reliable sign of increased estrogen production is breast enlargement. Initially, breast budding may be unilateral or asymmetrical. Gradually, the breast diameter increases, the areola darkens and thickens, and the nipple becomes more prominent. Distinguishing glandular breast tissue from fat, which can mimic true breast tissue, is essential. Examining the patient while she is in the supine position usually minimizes the chance of misinterpreting fat as true breast enlargement.

Genital examination may or may not reveal pubic hair, but enlargement of the clitoris indicates significant androgen excess that must be promptly evaluated. The vaginal mucosa, which is a deep-red color in prepubertal girls, takes on a moist pastel-pink appearance as estrogen exposure increases.

Mild acne may be normal in early puberty, but rapid onset of severe acne, like clitoral enlargement, should increase suspicion of an androgen-excess disorder.

Precocious puberty in boys

The earliest sign of CPP is enlargement of the testes, which depends on increased production of follicle-stimulating hormone (FSH); testicular length is more than 2.5 cm, or testicular volume (with Prader orchidometer beads) is 4 mL or more. If progressive signs of androgen excess occur in a boy without increased testicular size, consider possible causes of precocious pseudopuberty, including congenital adrenal hyperplasia, familial male precocious puberty, and Leydig-cell tumors (a testicular nodule is usually palpable). Human chorionic gonadotropin (HCG)–secreting tumors somewhat increase testicular size by stimulating testicular Leydig-cell LH receptors.

Other signs of puberty (eg, penis growth, reddening and thinning of the scrotum, increased pubic hair) are a consequence of increased testosterone production and occur within 1-2 years after testicular enlargement.

Pubic hair growth that occurs without penis and testicular enlargement and other signs of increased androgen production indicate a condition such as premature adrenarche or a mild, nonclassic form of congenital adrenal hyperplasia rather than true puberty.

Later signs of puberty include the pubertal growth spurt, acne, voice change, and facial hair.



The timing of puberty has a genetic component. A history of early puberty in a parent or sibling is relevant and decreases the likelihood that early puberty has an organic cause. A study from Israel estimated that precocious puberty was familial in one fourth of cases and that the predominant mode of inheritance was autosomal dominant. [28]

An increased body mass index (BMI) has been strongly associated with earlier onset of thelarche and menarche, [29]  with, in some studies, the association being stronger in White females than in Black ones. However, the relationship between body fat and puberty is complex and has many exceptions, and although body weight and fat mass are clearly among the factors that may influence puberty onset in girls, obesity is not definitely associated with early puberty in boys, with only some studies showing a relationship.

A longitudinal study of 354 girls by Lee et al found that increased BMI at age 3 years and the rate of increase in BMI from age 3-6 years were both positively associated with an earlier onset of puberty. [30]  In addition, a meta-analysis of two datasets from adolescent girls in 34 countries in Europe and North America revealed an inverse association between age at menarche and individual BMI. [31]

Genetic factors that have been associated with idiopathic central precocious puberty in females include gain of expression in the kisspeptin gene (KISS1) and gain- or loss-of-function mutations in the kisspeptin receptor gene (KISS1R), the makorin ring finger protein 3 gene (MKRN3), and the delta-like homologue 1 gene (DLK1). Genes that are suspected to play a role in the progression of idiopathic precocious puberty, but whose function in this condition requires clarification, include gamma-aminobutyric acid receptor subunit alpha-1 (GABRA1), lin-28 homolog B (LIN28B), neuropeptide Y (NPYR), tachykinin 3 (TAC3), and tachykinin receptor 3 (TACR3). [32, 33]