An Overview of Puberty

Puberty Disorders

Abdulmoein Eid Al-Agha, FRCPCH Professor of Pediatric Endocrinology, King Abdulaziz University Hospital, Website: http://aagha.kau.edu.sa

Puberty • Physiological transition from childhood to reproductive maturity • Associated with: – Growth spurt – Appearance of both primary and secondary sexual characteristics in children – Occurs between 8 and 13 yrs in girls – Occurs between 9 and 14yrs in boys

Puberty: Influencing Factors • Genetics: 50-80% of variation in pubertal Timing. • Environmental factors: nutritional status, environmental hormonal disruptors ( for example usage of plastics, nylon or food products rich with estrogen. • Obesity: as obese children tend to have earlier puberty as their adipose tissues produces Leptin peptide which has stimulating effects on the hypothalamus.

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Puberty in Girls Sexual Changes

Psychological Changes

Somatic Changes - Widening of pelvis

- Shy and Isolated - Breast enlargement - Acne and oily skin

-Menstrual cycles

- Very Sensitive

- Increase body fat in feminine areas - Pubic and auxiliary hair growth

- Growth spurt Increase Carrying angle

Secondary sexual Changes • 5 stages from childhood to full maturity described by Dr. Tanner (British citizen). • Stage 1 is prepubertal, while stage 5 is full adult. • In females; 5 stages for breast development and another 5 stages for Pubic hair. • In males; 5 stages for genital development and another 5 stages for Pubic hair. • Secondary sexual characteristics – starting age 8– 13 yrs in girls – starting age 9 – 14yrs in boys

Tanner Stages Females

Puberty: Girls • Breast enlargement (Thelarche) usually first sign, Often begins unilateral then become in both sides. • Second stage is pubic & axillary hair development (Adrenarche), in addition to oily skin & hair with Acne ( this stage is equally happened in both sexes) due to adrenal androgens. • Menarche usually 2-3 yrs after breast development. • Growth spurt peaks before menarche.

Puberty: Girls Widening of pelvis & carrying angle. Major increase in bone mineral density. Increased adipose tissue with typical female distribution (buttocks, upper thighs & breast tissues).  95% of growth happened < menarche Menarche usually by age 13-14 years. Increased in muscle bulk but not to same extent as males.

Menarche  During puberty estradiol levels fluctuate widely (reflecting successive waves of follicular development that fail to reach ovulatory stage)  Endometrium is affected by estradiol.  Undergoes cycles of proliferation & regression until point where withdrawal of estrogen results in the first menstrual bleed (menarche)  Increase of only 5% of final height after menarche

Puberty in boys Sexual Changes Testicular enlargement

Psychological Changes

Somatic Changes Facial, pubic and auxiliary hair growth Growth spurt

Aggressive

Acne and oily skin Voice change

Spermatogenesis

Widening of shoulders

Positive selfimage and mood

Increased muscle mass

Decreased adipose tissue Gynecomastia (usually disappears within 2 years)

Puberty: Boys  First sign is testicular enlargement (often go unnoticed ).  Pre-pubertal testicular volume is 1-3 ml  Puberty begins when testicular volume is 4ml and above.  Penile and scrotal enlargement occur approx 1 yr after testicular enlargement.  Pubic hair appears at same time.

Tanner Stages Males

Orchidometer

Pubertal Growth Spurt: Boys  Occurs later than in females by average 2 years.  Testosterone less of a stimulus to GH responsiveness than estradiol.  Testosterone required in larger concentrations to produce same anabolic effect.  Greater and later growth spurt in boys.

Final adult height • Puberty usually completed within 3 - 4 yrs of onset • Left wrist x-ray to assess bone age • Final adult height results from complete fusion of epiphyses – Occurs approx 1-2 yrs after menarche

Precocious Puberty 

In girls, defined as onset of puberty “breast enlargement” before age of 8 years.

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In boys, defined as onset of puberty testicular enlargement before age of 9 years.

 5 times more common in girls than boys.

Types   

Central, True, GnRH dependent.  89-98% of cases (major type) Peripheral, Pseudo, GnRH Independent.  10 – 15 % of cases (not major type) Isolated Forms:  Isolated benign Thelarche.  Isolated benign Adrenarche / Pubarche.

Central, True, GnRH dependent 

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Result from premature activation of Hypothalamus-Pituitary-Gonadal axis The pulsatile GnRH secretion leads to pulsatile secretions of LH and FSH with subsequent release of sex steroids Similar to normal mechanism but happened earlier than expected age

Central, True, GnRH dependent Etiology „Idiopathic

 most girls ( 90 %) „Secondary

 most boys ( 70-80%)

Central, True, GnRH dependent CNS disorders 

Hypothalamic Hamartoma.

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Glioma, Astrocytoma, Craniopharyngioma, Ependymoma, germinoma.

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CNS radiation therapy.

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Post trauma (surgery). Meningitis, encephalitis, Brain abscesses.

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Neurological insult & mental retardation.

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Hydrocephalus.

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Prolonged primary hypothyroidism.

Etiology of peripheral type   

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Gonadal: McCune-Albright, tumor, cyst. Adrenal: non classical congenital adrenal hyperplasia, tumors. Ectopic: hCG secreting tumors:  Germinoma, Hepatoblastoma. Exogenous source of sex hormone (contraceptive) Familial male dependent (Testotoxicosis)

Exogenous source of estrogens

McCune Albright Syndrome

Pubertal Delay Definition: 

Girls: Lack of breast development by age 13 years. More than five years between breast growth and menstrual period.  Lack of pubic hair by age 14 years.  Failure to menstruate by age 16 years. Boys:  Lack of testicular enlargement by age 14 years.  Lack of pubic hair by age 15 years.  More than five years to complete genital Enlargement.  

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TYPES 

Two major types:  Hypogonadotrophic hypogonadism  Hypothalamic -Pituitary defects  Hypogonadotrophic hypogonadism  Gonadal failure

Causes of Hypogonadotrophic Hypogonadism  Constitutional delay of growth &Puberty.  Malnutrition.  Excessive exercise.  Isolated Gonadotropin deficiency.  Brain tumors:  Craniopharyngioma, Astrocytoma, Glioma, histiocytosis X, germinoma, prolactinoma.

 Iron overload (hemosiderosis)  GnRH receptor abnormalities.

Constitutional delay of Puberty  Most common cause of pubertal delay.  Physiological cause.  Delayed puberty often found in siblings or parents.  Diagnosis of exclusion.  Bone age is delayed & consistent with degree of pubertal maturation (usually delayed by 2yrs or more.  Often associated with constitutional short stature.

Hypogonadotrophic hypogonadism  Rare (~10%)  Hypothalamic deficiency 

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GnRH deficiency - may be isolated or associated with other features e.g. anosmia (Kallman's syndrome), cognitive impairment and dysmorphic features (Prader-Willi syndrome).

Pituitary deficiency 

Gonadotropin deficiency or more commonly associated with any form of pan hypopituitarism.

Kallman Syndrome  Syndrome of isolated Gonadotropin deficiency.  Present with anosmia or hypo-osmia.  KAL-1 gene encodes protein (anosmin) required for GnRH neurons to migrate from olfactory placode to cribiform plate.  Associated with harelip, cleft palate, and congenital deafness

Kallman Syndrome

Syndromes associated with pubertal delay

 Prader-Willi syndrome.  Laurence Moon syndrome.  Septo-optic dysplasia.  Bardet-Biedl syndrome.

Hypergonadotropic Hypogonadism 

Sex chromosome abnormalities:  Klinefelter's syndrome in boys (47XXY)  Turner's syndrome in girls (45XO)

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Gonadal dysgenesis with normal Karyotype Gonadal damage

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viral (e.g. mumps Orchitis) Iatrogenic (surgical, chemotherapy or radiotherapy) Autoimmune destruction(often associated with other autoimmune disease). Gametes generally more sensitive to damage that steroid secreting cells

Klinefelter's syndrome

Turner syndrome

Chronic illness 

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Delay in pubertal development is very common in the presence of any serious illness e.g. chronic renal failure, bowel or liver diseases. Progress depends on the course of the underlying disease. Endocrine causes of delay puberty include hypothyroidism, GH deficiency and excess glucocorticoid.

Learning Points (2) Idiopathic central precocious puberty in a boy is very unusual so early puberty in boys needs extensive investigation which is usually unnecessary in early puberty in a girl  Delayed onset on puberty ( more than13 years in girls, 14 years in boys) is much commoner in boys than girls and is usually idiopathic 