Normal pubertal development: part II: clinical aspects of puberty.

Stages of Puberty and Their Evaluation Sexual Maturity Rating (SMR) staging of sexual development, also known as Tanner staging, provides a means of discretely documenting a child’s progression through puberty by inspection. Separate scales are used for breast (female), genital (male), and pubic hair (both sexes) development (Figs. 1 and 2). (1)(2)(3) By definition, SMR stage 1 is prepubertal. Pubertal development of the gonads is indicated specifically by thelarche (breast stage 2) in girls (Fig. 1) and testicular enlargement (genital stage 2) in boys (Fig. 2). Pubertal development is ongoing at stage 3, nearly complete by stage 4, and complete and adultlike at stage 5. The limitation of the SMR system is that defining early breast and testicular developmental stages accurately requires palpation, not just visual inspection. (4)(5) Inspection of breast development does not enable the distinction between breast tissue development and fat deposition (adipomastia), which is a common confounder. The distinction is best made by palpation of the subareolar breast bud. Direct measurement of testicular size by palpation is likewise preferable to the SMR genital staging system, which relies on a “gestalt” visual estimation of testicular enlargement (a follicle-stimulating hormone [FSH] effect on the seminiferous tubules) that is confounded easily by penile size, which varies constitutionally and is stimulated by androgen and obscured by obesity. A testicular long diameter of 15/16 in (volume 3.0 mL, direct determination of which requires an orchidometer measurement (6)) indicates entry into puberty and is the key feature of genital stage 2 (Fig. 2). (7)(8)(9)(10) Mature pubertal testicular development (stage 5) is indicated by attainment of a testicular long diameter of 1.5 to 2.0 in (12 to 27 mL). (3)(9)(11) Testicular volume determined by ultrasonography is about half of that determined by orchidometry but correlates highly. (10) Pubarche is not specific evidence of pubertal function of the gonads because these changes may result from either gonadal or adrenarchal androgen production. Although pubic hair stage 2 may indicate early sexual hair growth, it also may result from generalized hypertrichosis. Thus, pubic hair stage 2 is a less accurate indicator of pubertal androgen production than pubic hair stage 3, the appearance of frank sexual hair (Fig. 1). (4) Although pubic hair stages 2 to 4 may result solely from adrenarchal androgens in both sexes, the development of a “male escutcheon” (stage 6, Fig. 2), ie, sexual hair extending up the linea alba, specifically suggests a concentration of androgen above that normally found in females.