Case Based Pediatrics For Medical Students and Residents
Department of Pediatrics, University of Hawaii John A. Burns School of Medicine
Chapter XX.1. Puberty
Sherrel L. Hammar, MD
March 2002

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This is a 15 year old boy who is seen by his primary care physician for short stature and delayed sexual development. His past medical history is unremarkable except for asthma during early childhood, which has been well controlled. He is currently on no medications. He is an average student currently in the 9th grade and is the smallest in his class. He has been harassed by older classmates because of his size. His parents are concerned because Jim is becoming withdrawn and a "loner".

PMH: Pregnancy and delivery were uncomplicated. Birth weight and length were 3.86 kg (8.5 pounds) and 51 cm (20"), respectively. His HC was 35 cm. His immunizations are current.

Family History: His mother is 48 years old and in good health. Her height is 167 cm (50th %tile). Her menarche began at age 13.0 years. His father is 51 years old, also in good health. His height is 184.0 cm (75th %tile). His father's onset of puberty is not known but he was shaving regularly by age 15. There is one older male sibling age 18 who is in good health. His puberty began at age 11 years. There is no history of smoking, alcoholism, mental illness, drug abuse or learning problems in the family.

Exam: VS T 37.1, P 110, R 32, BP 100/60. Ht. 158 cm (3rd %tile), Wt. 42.0 kg. (10th %tile). He is pale and anxious but cooperative. His HEENT exam is normal. His chest is clear. Heart regular, no murmurs. His pulses are symmetrical and equal. There are no masses or areas of tenderness in his abdomen. Genitalia: Normal circumcised phallus, SMR (Tanner) pubic hair stage 1, genital stage 2. His testes are firm, 2.5 cm in length and 4 ml in volume. His scrotum is reddened and stippled. The remainder of his physical exam is unremarkable.

Lab: CBC: Hgb 13, WBC 9.5, normal differential, platelets 350,000. UA is normal. Bone Age: (left hand and wrist) 12.0 years. LH and FSH are decreased but normal for SMR stage 1-2.

Impression: Constitutional Short Stature, Delayed Puberty

Clinical Course: Over the next 6 months, pubic hair growth is noted. His testes enlarge to 3-4 cm in length and his height increases by 5 cm.


Puberty refers to the biological changes that lead to reproductive capability while adolescence generally refers to the psychosocial changes that occur. The sequence of events that occur during puberty are generally fairly predictable. The timing of these events, however may be highly variable.

Sexual Maturity Ratings (SMR), also known as Tanner stages, utilize pubic hair stages and breast development stages for females, and pubic hair stages and male genital development stages for males. Table 1 categorizes the pubic hair SMR stages for males and females. Table 2 categorizes female breast development SMR stages. Table 3 categorizes male genital development SMR stages, which are based on testicular size.

Table 1. SMR Pubic Hair Stages: Mean chronologic age (CA) and bone age (BA) in males and females (in years)
SMR
Male CA
Male BA
Female CA
Female BA
I. None
II. Sparse
12.2
13.5
10.4
11.5
III. Coarse, easily visible
13.5
14.2
12.2
12.2
IV. Confined to suprapubic area
14.2
14.2
13.0
13.2
V. Adult type on medial thighs
14.9
14.0
Stage II-V = 2.7 yrs avg.

Table 2. SMR Female Breast Stages: Mean chronologic age (CA) and bone age (BA) in females (in years)
SMR
CA
BA
I. No development
II. Bud
10.9 (8.5-13.3)
10.5
III. Breast tissue beyond areola
12.2
12.0
IV. Secondary mound
13.2
13.5
V. Adult
14.0
15.0
Peak height velocity
12.2 (10.2-14.2)
12.5
Menarche
12.7 (10.5-15.5)
Stage II to Stage III = 1.3 yrs avg.
Stage III to Stage V = 2.4 yrs avg.

Table 3. SMR Male Genital Stages. Mean chronologic age (CA) and bone age (BA) in males (in years)
SMR
Testicular Length
Testicular Volume
CA
BA
I.
<2.5cm
<4ml
II.
>2.5cm
4-6 ml
11.2 (9.2-14.2)
11.5 (9.0-13.5)
III.
>3.0cm
6-10 ml
12.9
13.2
IV.
>4.0cm
10-15 ml
13.8
14.5
V.
>5.0cm
>15ml
14.7
Peak height velocity
13.9 (12.3-15.5)
14.5

Females initially show a deposition of adipose tissue and widening of the pelvis and changes in the contour of the hips. The first clinical sign is thelarche (the appearance of breast buds) and adrenarche (the appearance of dark straight pubic hair over the mons veneris, also called the mons pubis). These changes identify a SMR stage (or Tanner stage) II (see tables 1 and 2). Breast development over the next 4 years will proceed from breast stage II (secondary mound of breast tissue to adult breast stage V). Development of pubic hair starts about 1 year after breast budding and may take place over a 1.5 to 3.5 year period. During SMR stage 3, girls experience a very rapid increase in their height. The peak of their height growth (PHV=peak height velocity) should take place before the onset of menarche in most girls. Menarche occurs six months after the PHV and just prior to stage IV of breast development. Most western girls achieve their menarche around 12.4 to 12.8 years of age. African-American girls are maturing earlier.

Puberty in boys also follows a regular sequence of events, but lacks the clear cut landmarks such as breast development and menarche. In the male, the pubertal growth spurt is a late event starting about two years later than in females. The onset of pubertal changes however, are only about 6 months later than in females (see tables 2 and 3). Enlargement of the testes indicates the transition from genital stage I to Stage II, beginning at an average age of 11.5 years. Penile growth occurs about one year later. This is usually preceded by the appearance of pubic hair at the base of the phallus progressing through pubic hair stages II to V. Pubic hair stage III is followed by the appearance of axillary and facial hair growth. Testicular growth is completed anytime between 13.5 and 17 years of age. Growth of the penis reaches a SMR (Tanner) stage V between 12.5 and 16.5 years of age. Nocturnal emissions (wet dreams) may first appear during SMR stage III.

There is a common misconception that the difference between the onset of puberty in males and females is 2 years. This applies only to the growth spurt and not to pubertal (SMR) changes.

The patient described above is not only short statured but is delayed in his pubertal development. On the basis of the physical findings described, he would fit a presumptive diagnosis of constitutional delay of growth and maturation.

Boys with a constitutional delay of growth and maturation, usually have a normal birth weight and length, and progress along their normal growth centile for the first several years of life, following which, they begin to deviate and grow at or below the 3rd percentile throughout childhood. At the time when normal puberty should begin, there is often a marked fall off in growth (pre-adolescent dip) due to a diminished secretion of growth hormone. This transient fall in growth hormone is probably due to failure of sex hormone production and stimulation.

Skeletal maturation is usually delayed. When the bone age eventually reaches the skeletal age when puberty is expected, it is likely that early signs of sexual maturation will also appear, which is the stage of testicular enlargement (SMR genital stage II).

Often a familial pattern of pubertal delay is reported. The incidence of affected males is about 10%. Patients with constitutional delay in growth and maturation usually do not reach their "mid parent" or predicted height. Catch up growth is largely dependent upon the delay of bone maturation at the time of diagnosis, indicating that there may be a genetic or familial component to their short stature.

In most males, a watch and wait approach is indicated for six to twelve months. The patient presented could have been prescribed a short term course of testosterone or gonadotropins in order to stimulate sexual maturation and growth hormone production. In general, such treatment has been reserved for teenagers with significant behavior or psychological (self image) problems due to their delayed puberty.

In most cases, the evaluation of a patient suspected of delayed sexual maturity can be conservative. A thorough family history, physical examination, and assessment of sexual maturity stage will often show signs of early pubertal changes. The bone age is usually delayed and reflects the physical delays and the height age of the patient (the age corresponding to the 50%ile of the patient's actual height). Gonadotropins usually reflect the sexual maturity status of the patient. A chromosomal karyotype is indicated for all short statured girls who are delayed (for possible Turner's syndrome) and for boys who are tall with small soft testes with or without delayed sexual maturity (Klinefelter's syndrome).

Table 4. Causes of Short Stature
. . . . I. Constitutional Short Stature
. . . . II. Primordial Dwarfism (intrauterine growth retardation)
. . . . III. Endocrine Causes
. . . . . . . . A. Growth Hormone Deficiency
. . . . . . . . . . . . 1. Congenital
. . . . . . . . . . . . 2. Acquired
. . . . . . . . . . . . . . . . a. Hypothalamic/Pituitary Tumors
. . . . . . . . . . . . . . . . b. Head Trauma
. . . . . . . . . . . . . . . . c. CNS infections
. . . . . . . . . . . . . . . . d. Psychosocial Dwarfism
. . . . . . . . . . . . 3. Laron Dwarfism
. . . . . . . . . . . . 4. Hypothyroidism
. . . . . . . . . . . . 5. Syndromes of Short Stature
. . . . . . . . . . . . . . . . a. Turner's Syndrome (gonadal dysgenesis)
. . . . . . . . . . . . . . . . b. Noonan's Syndrome
. . . . . . . . . . . . . . . . c. Prader-Willi Syndrome
. . . . IV. Chronic Disease
. . . . . . . . A. Heart Disease
. . . . . . . . B. Pulmonary
. . . . . . . . . . . . 1. Cystic Fibrosis
. . . . . . . . . . . . 2. Asthma
. . . . . . . . C. GI Disorders
. . . . . . . . D. Hepatic Disease
. . . . . . . . E. Renal
. . . . V. Iatrogenic
. . . . . . . . A. Corticosteroids, anabolic steroids
. . . . . . . . B. ADHD meds

Table 5. Causes of Delayed Puberty
. . . . I. Constitutional Delay in Growth and Maturation
. . . . II. Hypogonadotropic hypogonadism
. . . . . . . . A. Central nervous system disorders
. . . . . . . . . . . . 1. Tumors
. . . . . . . . . . . . . . . . a. Craniopharyngiomas
. . . . . . . . . . . . . . . . b. Gliomas
. . . . . . . . . . . . . . . . c. Germinomas
. . . . . . . . . . . . 2. Radiation Therapy
. . . . . . . . . . . . 3. Congenital Malformations
. . . . . . . . B. Isolated Growth Hormone Deficiency
. . . . . . . . . . . . 1. Kallmann's Syndrome
. . . . . . . . C. Miscellaneous Disorders
. . . . . . . . . . . . 1. Prader-Willi Syndrome
. . . . . . . . . . . . 2. Hypothyroidism
. . . . . . . . . . . . 3. Malnutrition
. . . . . . . . . . . . 4. Anorexia Nervosa
. . . . . . . . . . . . 5. Exercise amenorrhea
. . . . . . . . . . . . 6. Cushing's
. . . . . . . . . . . . 7. Diabetes
. . . . III. Hypergonadotropic hypogonadism
. . . . . . . . A. Turner's Syndrome
. . . . . . . . B. XX and XY gonadal dysgenesis
. . . . . . . . C. Polycystic ovary Syndrome
. . . . . . . . D. Noonan's Syndrome


Questions

1. What is the first objective physical sign of puberty in the male? In the female?

2. The difference in age between the initiation of pubertal (sexual) changes in the male and female is how many months?

3. What is the definition of delayed puberty? Precocious puberty?

4. What is the height age?

5. The best indicator of the biological age of the individual is?


References

1. Kreipe RE. Normal Somatic Adolescent Growth and Development. In: McAnarney E, Kreipe RE, Orr D, Comerci G (eds). Textbook of Adolescent Medicine. 1992, Philadelphia: W.B. Saunders & Co., pp. 44-68,

2. Kreipe R E, McAnarney ER. Adolescent Medicine. In: Behrman RE, Kliegman RB (eds). Essentials of Pediatrics, 2nd edition. 1994, Philadelphia: W.B. Saunders & Co., pp. 215-229.


Answers to questions

1. Enlargement of the testes measuring greater than 2.5 cm in length and scrotal changes are the first signs of puberty in the male. The appearance of breast buds in the female indicate the onset of puberty.

2. There is approximately 6 months difference in the age of onset of sexual maturation in the female vs. the male.

3. Puberty is delayed when there is no sign of pubertal development by age 13 years in girls and 14 years in boys. Precocious puberty is secondary sexual development occurring before age 9 years in boys or 8 years in girls.

4. Height age is the age at which the height of the individual is equal to the height of 50 percent of a reference standard population by age and gender. This is done by taking the patient's height and finding the age, at which this height is the 50th percentile on an appropriate height grid.

5. The best indicator of the biological age of the individual is the skeletal age (bone age).


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