Disorders of puberty

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CHAPTER 43

Disorders of puberty

1. What physiologic events initiate puberty?

2. How is pubertal development measured?

Sexual maturity is determined by physical examination and is described in a scale devised by John Tanner in 1969 (Table 43-1). Because of the distinct actions of adrenal androgens and gonadal steroids, it is important to distinguish between pubic hair and breast development in girls and between pubic hair and testicular development in boys. In all cases, Tanner stage I is prepubertal and Tanner stage V is complete maturation. In addition to the physical examination, the tools to assess pubertal development may include determination of bone age, growth velocity, growth pattern, and specific endocrine studies.

TABLE 43-1.

TANNER STAGES OF PUBERTAL DEVELOPMENT

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Data from Marshall WE, Tanner JM: Variations in the pattern of pubertal changes in girls. Arch Dis Child 44:291–303, 1969; Variations in the pattern of pubertal changes in boys. Arch Dis Child 45:13–23, 1970.

3. What is adrenarche?

4. What controls the pubertal growth spurt?

5. What is the normal pattern of puberty in boys?

6. What is the normal pattern of puberty in girls?

Girls normally begin puberty between age 8 and 13 years (mean age: 10.4 years for white girls, 9.8 years for Hispanic girls, and 9.5 years for black girls). The initial pubertal event is typically the appearance of breast buds, although a small percentage of girls will develop pubic hair first. In an even smaller percentage of girls, menstrual cycling may appear first. Initial breast development often occurs asymmetrically and should not be of concern. Breast development is primarily under the control of estrogens secreted by the ovaries, whereas growth of pubic hair and axillary hair results mainly from adrenal androgens. Unlike in boys, the pubertal growth spurt in girls occurs at the onset of puberty. Menarche usually occurs 18 to 24 months after the onset of breast development (mean age: 12.5 years). Although most girls have reached about 97.5% of their maximum height potential at menarche, this can vary considerably. Consequently, age of menarche is not necessarily a good predictor of final adult height.

7. What constitutes sexual precocity in boys and girls?

Precocious puberty is defined as pubertal development occurring below the limits of age set for normal onset of puberty. In girls, this is puberty before 8 years in white girls, 6.6 years in black girls, and 6.8 years in Hispanic girls. For boys, precocious puberty is development occurring before 9 years in white and Hispanic boys and 8 years in black boys. Girls showing signs of puberty between 6 and 8 years often have a benign, slowly progressing form that requires no intervention. Consequently, evaluation and treatment of girls who start puberty between 6 and 8 years should depend on factors such as family history, rapidity of development, the presence of central nervous system (CNS) symptoms, and family concern. Girls who are short and start puberty between 6 and 8 years may also benefit from evaluation. In children who present with early pubertal signs, precocious puberty must be distinguished from normal variants of puberty, such as benign premature thelarche and benign premature adrenarche.

8. Which two common benign conditions in girls are often confused with precocious puberty?

9. How is benign premature thelarche diagnosed?

10. How is benign premature thelarche treated?

11. How is benign premature adrenarche diagnosed?

Benign premature adrenarche is caused by early secretion of the adrenal androgens, primarily DHEA and DHEA-S, and is suspected when clinical signs of androgen exposure are present, such as pubic hair, axillary hair, acne, or body odor. A child who has benign premature adrenarche and Tanner stage II pubic hair development will have adrenal androgen values similar to those normally found in a pubertal child at the same stage of development. As in premature thelarche, growth rate and bone age are typically not accelerated. If signs of puberty are rapidly progressing, or if there is evidence of increased linear growth and advanced bone age, measurement of androgens (DHEA-S, androstenedione, and testosterone) is performed to evaluate for a serious virilizing disorder such as congenital adrenal hyperplasia (CAH) or an adrenal tumor. A 17-hydroxyprogesterone (17-OHP) level may also be drawn as the first screen for late-onset CAH.

12. How is benign premature adrenarche treated?

13. What clinical findings are associated with precocious puberty?

14. In which sex is precocity more prevalent?

15. How is the diagnosis of precocious puberty made?

The diagnosis of precocious puberty requires the appearance of the physical signs of puberty before the defined age limits, as discussed previously. In both boys and girls, a complete history should be taken, with careful consideration of any exposure to exogenous steroids or estrogen receptor agonists (e.g., lavender oil or tea tree oil), onset of pubertal signs and rate of progression, presence or history of CNS abnormalities, and pubertal history of other family members. Height measurements should be plotted on a growth chart to determine growth pattern and growth velocity. A physical examination should be performed with a focus on Tanner staging, the presence of café-au-lait spots, and neurologic signs. One of the early steps in evaluating a child with early pubertal development should be to obtain a radiograph of the left hand and wrist to determine skeletal maturity (bone age). If the bone age is advanced, further evaluation is warranted. Sex steroid levels should be measured, especially in boys, because testosterone levels higher than the prepubertal range (> 10 ng/dL) confirm pubertal status. For girls, estradiol measurements are less reliable indicators of puberty, because most commercial assays are not sufficiently specific or sensitive to demonstrate an increase during early puberty.

16. How does GnRH-dependent (central) precocious puberty differ from GnRH-independent (peripheral) precocious puberty?

It is usually difficult to distinguish GnRH-dependent (central) from GnRH-independent (peripheral) precocity on physical examination. Central precocious puberty involves activation of the GnRH pulse generator, an increase in gonadotropin secretion, and a resultant increase in the production of sex steroids. Consequently, the sequence of hormonal and physical events in central precocious puberty is identical to the progression of normal puberty. Peripheral precocious puberty occurs independent of gonadotropin secretion. Although the possible causes of peripheral precocious puberty are more numerous (Box 43-1), central precocity accounts for most cases.

17. What is the single most important test in establishing a specific diagnosis?

18. When is a magnetic resonance imaging (MRI) study of the brain indicated?

19. How is central idiopathic precocious puberty treated?

Children with central precocious puberty can be treated with GnRH agonists, such as leuprolide. GnRH agonists disrupt the endogenous pulsatile GnRH, thus downregulating pituitary GnRH receptors and decreasing gonadotropin secretion. The most important clinical criteria for GnRH agonist therapy is documented progression of pubertal development, which is based on the recognition that many girls with central precocious puberty, especially those between 6 and 8 years old, have a slowly progressive form and reach a normal adult height without intervention. With GnRH agonist treatment, physical changes of puberty regress or cease to progress, and linear growth slows to a prepubertal rate. Pubic hair and axillary hair typically do not regress. Projected final adult height often increases because of a slowing of skeletal maturation. GnRH agonists are generally given as a monthly depot intramuscular injection, and side effects are rare. There is also a small hydrogel implant that can be placed under the skin that releases a GnRH agonist (histrelin) continuously for about 1 year. Children receiving GnRH agonists should be monitored every 4 to 6 months to evaluate for pubertal regression or treatment failure. After discontinuation of therapy, pubertal progression resumes, and normal rates of fertility are expected.

20. What findings suggest peripheral precocious puberty?

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