Pediatric Annals

Healthy Baby/Healthy Child 

Puberty: Onset and Progression

Leah Khan, MD

Abstract

Puberty is an important process that providers of health care to children and adolescents should be comfortable discussing. The normal process of puberty is complex and involves many different hormonal pathways. A clear understanding of these pathways will help providers counsel patients on what to expect as they anticipate and progress through puberty as well as be alerted when puberty is not progressing normally. Both early and late puberty can have physical and psychological implications for the pediatric population. Being familiar with the common causes and initial testing of abnormal puberty will allow the primary care provider to monitor appropriately and initiate further investigation if warranted. This article reviews both the typical pubertal pathway as well as delayed and premature puberty and their common causes. [Pediatr Ann. 2019;48(4):e141–e145.]

Abstract

Puberty is an important process that providers of health care to children and adolescents should be comfortable discussing. The normal process of puberty is complex and involves many different hormonal pathways. A clear understanding of these pathways will help providers counsel patients on what to expect as they anticipate and progress through puberty as well as be alerted when puberty is not progressing normally. Both early and late puberty can have physical and psychological implications for the pediatric population. Being familiar with the common causes and initial testing of abnormal puberty will allow the primary care provider to monitor appropriately and initiate further investigation if warranted. This article reviews both the typical pubertal pathway as well as delayed and premature puberty and their common causes. [Pediatr Ann. 2019;48(4):e141–e145.]

Puberty is the process through which reproductive maturation occurs, and it is initiated by the hypothalamic-pituitary-gonadal (HPG) axis (Figure 1).1 The hypothalamus is activated and excretes gonadotropin-releasing hormone (GnRH), which stimulates the pituitary to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH).2,3 These hormones then stimulate the testes or ovaries to enlarge and produce testosterone or estrogen, respectively.2,3 In girls, this is accompanied by thelarche, which is the onset of breast development with the formation of breast buds.4–6 This is then followed by growth acceleration, skeletal maturation, and subsequently vaginal bleeding (menarche).5 Another important component of puberty is adrenarche, which is the release of hormones from the adrenal gland.5,7 This process occurs independently of of the HPG axis.5 The adrenal cortex releases adrenal androgens, leading to the development of pubic hair (pubarche), axillary hair, acne, and adult body odor.5,7 In boys, adrenarche also triggers penile enlargement and voice changes.5

The hypothalamic-pituitary-gonadal axis. FSH, follicle-stimulating hormone; GnRH, gonadotropin-releasing hormone; LH, luteinizing hormone.

Figure 1.

The hypothalamic-pituitary-gonadal axis. FSH, follicle-stimulating hormone; GnRH, gonadotropin-releasing hormone; LH, luteinizing hormone.

To monitor and also communicate the progression of puberty in males and females, a staging system has been developed, called Tanner Staging but more recently referred to as the Maturity Rating Scale (Table 1). It takes into account penile and testicular growth along with genital hair patterns in boys and breast development and genital hair patterns in girls.1

Maturity Rating Scale

Table 1.

Maturity Rating Scale

It is important for providers to understand the expected timing and progression of puberty and the hormonal elements that control it so we can better counsel patients as they anticipate and experience the changes of puberty. Whether it occurs at a normal time, early, or late, it is a complicated and confusing subject for many of our patients. Abnormal puberty, in particular, can have physical, medical, and emotional implications for our patients. Although abnormal timing of pubertal changes is often benign, there are also important causes that must be further evaluated. The following text discusses the typical onset and progression of puberty as well as reviews delayed and premature puberty.

Normal Puberty

The age for normal onset of puberty is based on data from the 1960s.8 Pubertal onset is considered normal between ages 8 and 13 years in girls and ages 9 and 14 years in boys.8 Puberty usually lasts for about 3 years from onset to full maturation.5

For boys, puberty begins with testicular enlargement.1 This is followed by hair development, penile enlargement, and a growth spurt.1 Boys typically grow 13 to 14 inches and gain an average of 40 pounds during puberty.9 Their rapid growth typically occurs about age 13.5 years.9 In girls, puberty starts with the development of breast buds, which is followed soon after by the development of pubic hair.1 Menarche typically occurs about 2 to 2.5 years after breast buds appear.5 Girls generally grow about 10 inches (with 1–2 inches of that growth after menarche) and gain about 25 pounds during puberty.9 Girls experience their most rapid period of growth shortly after the start of puberty, most commonly around age 11.5 years.2,9

For both boys and girls, the growth spurt starts about 1 year after genital enlargement initiates.3 Growth begins with enlargement of the hands and feet, followed by the lengthening of arms and legs.9 After that, boys' shoulders and girls' hips widen.9 Finally, the trunk lengthens, completing the growth spurt.9

Delayed Puberty

Delayed puberty occurs in about 2% of adolescents and is defined by the lack of any pubertal development by an age that is 2 to 2.5 standard deviations beyond the population mean.10 This is typically age 14 years in boys and age 13 years or no menarche by age 16 years in girls.10 In addition, lack of menarche more than 5 years after the onset of puberty is also considered delayed.5 Most often, delayed puberty is nonpathologic and is a variant of normal.10 The most common cause of delayed puberty is constitutional delay, which occurs when activation of the HPG axis is delayed and puberty begins at the extreme end of the normal spectrum and subsequently progresses normally.1–3,10 The diagnosis of constitutional delay, however, is one of exclusion, and more concerning causes must be ruled out. Other causes of delayed puberty are outlined below.

Hypergonadotropic Hypogonadism

Hypergonadotropic hypogonadism occurs when there is gonadal failure or the gonads have the inability to synthesize or process sex steroids.10 Children with this condition will have low estrogen or testosterone levels and elevated LH and FSH because the pituitary will be overproducing to try to stimulate the gonads, which are not responding appropriately.2,10

Permanent Hypogonadotropic Hypogonadism

Permanent hypogonadotropic hypogonadism occurs when there is an underlying central nervous system problem affecting either the hypothalamus (the pituitary is not stimulated) or the pituitary (does not produce LH and FSH).10 Examples of this type of cause include Turner syndrome, damage from radiation, and autoimmune disorders.2 FSH and LH will be low in these children. Some of these conditions may require long-term estrogen or testosterone replacement.2

Functional Hypogonadotropic Hypogonadism

Functional hypogonadotropic hypogonadism is a transient condition resulting in low FSH and LH due to another medical condition such as celiac disease, inflammatory bowel disease, sickle cell disease, cystic fibrosis, or anorexia.3,10 In general, decreased body fat in girls (as often seen in ballet dancers, gymnasts, and runners) can also delay puberty.2 When the underlying condition is managed, puberty will initiate and progress normally.

The workup of delayed puberty should begin with family history (as constitutional delay is familial in 50%–75% of cases).3,10 It is important to evaluate childhood growth patterns including height, weight, Tanner staging, and growth velocity.10 Obtaining information about the onset of puberty in parents and siblings is also helpful.10 Initial workup should include laboratory evaluation of LH and FSH, and a bone age.10 Depending on the history and physical examination findings, further testing including complete blood count, erythrocyte sedimentation rate, basic metabolic panel, liver function tests, urea, creatinine, estradiol, testosterone, insulin-like growth factor 1, thyroid-stimulating hormone, prolactin, karyotype, and a magnetic resonance imaging scan of the brain may be indicated.2,10

Once pathologic causes of delayed puberty are ruled out, different approaches can be taken to address constitutional delay. The most common approach is reassurance and expectant management. Supporting the patient with encouragement and assurance that he or she will go through a normal pubertal progression and eventually attain a normal adult height and physical maturity is generally all that is needed.2 In some circumstances, a provider may choose to “jump start” puberty by giving a short course of estrogen to girls or testosterone to boys.2,3 This will not affect the end results, but may get them to puberty a bit faster.3

Premature Puberty

Premature (or precocious) puberty is defined as pubertal changes that occur before age 8 years in girls and before age 9 years in boys.5,6,11 Premature pubertal changes can come in the form of any pubertal development before the expected age, but further testing may be needed to differentiate true precocious puberty from normal variants. True precocious puberty consists of progressive breast development, growth acceleration, and early menarche in females, and in males consists of penile and testicular enlargement, increased musculature, body hair, growth acceleration, and deepening of the voice.11

Early puberty is often more concerning than delayed puberty due to the long-term effects on health and development. For instance, is it more likely to be the result of pathology such as a brain tumor or congenital adrenal hyperplasia (CAH).5 Early puberty can also lead to premature bone maturation and short stature, and it also has psychological implications.5 For girls especially, even in puberty that occurs early on the normal spectrum, there is an increased frequency of risk-taking and delinquent behavior, earlier sexual debut, and more sexual partners.6

Central Precocious Puberty

Central precocious puberty occurs when there is a problem with the hypothalamus or the pituitary, leading to early stimulation of the HPG axis and propelling children into puberty.11 It is idiopathic in about 90% of girls but is more likely to be associated with pathology in boys, with up to 50% having an underlying cause.5,6 In girls, about 8% were found to have unexpected intracranial pathology, whereas 40% of boys were found to have unexpected intracranial pathology without neurologic findings.12 Girls with rapidly progressing signs of puberty or other associated neurologic signs are more likely to have intracranial pathology identified.12

Peripheral Precocious Puberty

Peripheral precocious puberty occurs when there is a problem with the ovaries or testes causing increased secretion of estrogen or testosterone.11 This can be caused by syndromes such as McCune-Albright syndrome, which is also associated with café-au-lait spots and fibrous dysplasia.6 It can also be caused by late-onset (mild) CAH.6 A rare but increasing cause of peripheral precocious puberty is exogenous exposure to testosterone or estrogen through things like lavender oil, tea tree oil, fennel, or prescription creams for adults.6,7,11

Normal Variants: Premature Adrenarche and Premature Thelarche

Premature adrenarche from elevated adrenal androgens can cause early pubic or axillary hair development but is generally benign.6 These children may have a slightly advanced bone age but will have no breast development or testicular enlargement.6,7 There is a small percentage of premature adrenarche that is caused by nonclassical (mild) CAH or an adrenal or gonadal tumor, but these are rare.7 In general though, there are no health problems associated with premature adrenarche.5 Some recent studies do suggest that there may be a correlated increased risk of polycystic ovarian syndrome (PCOS) in girls as they mature.11

Premature thelarche is also a normal variant and is rarely pathologic in younger children (<3 years) as long as no other signs of puberty are noted.4–6 The cause of benign premature thelarche is unknown.4 Benign premature thelarche occurs in older girls as well, but the onset of breast development between ages 6 and 8 years is more likely to be true precocious puberty and further evaluation is indicated.4 Laboratory testing for benign thelarche shows low LH and normal estradiol along with normal bone age.4 If benign, there is no treatment needed and the breast tissue often remains the same or regresses until typical growth occurs during the onset of true puberty.4

Evaluation of premature puberty should include a thorough history including the age of onset, tempo of progression, linear growth velocity, and presence of other secondary sex characteristics (eg, acne, body odor, menarche).6 Laboratory testing should include dehydroepiandrosterone sulfate, 17-hydroxyprogesterone, androstenedione, testosterone, FSH, LH, and estradiol (ideally drawn at 8 am).6,11 A bone age can also be helpful in the diagnosis.7 For those with a diagnosis of central precocious puberty, an MRI scan of the brain is also indicated.11

Treatment of premature puberty varies depending on the cause. Central precocious puberty should be treated to preserve adult height, decrease risk-taking behaviors, decrease obesity, and lower the risk of adult-onset diabetes and pre-menopausal breast cancer.6,13,14 The goal of treatment in central precocious puberty is to turn off the pituitary gland's production of LH and FSH; this is done with injections of leuprolide.11,14 For peripheral precocious puberty, treatment of the underlying condition or addressing the exogenous exposure to sex hormones is the best approach.

Trends in Puberty

Studies show a secular trend toward earlier onset of puberty in both boys and girls, although the trend does seem to be more significant in girls.6,8,13,14 Several factors are thought to be contributing to this, including an increase in obesity in girls (which tends to delay puberty in boys), endocrine-disrupting chemicals found in the environment, and even intrauterine growth restriction.1,6,7,13,14 Although the onset of pubertal changes has certainly shifted to an earlier age, the timing of menarche does not seem to be advancing as quickly as other changes such as breast development and hair growth.6 Studies show variable results regarding whether menarche itself is being affected by the trend of earlier onset of puberty.6,13

Conclusion

Puberty is a normal part of development and something that all providers of pediatric care should be comfortable discussing and managing. Whether our patients are progressing normally or if puberty is occurring early or late, it is important that we are able to counsel our families on when to be concerned, when we can watch and wait, and what constitutes “normal” and “abnormal” puberty. We also need a basic understanding of the factors that are driving puberty so that initial testing can be started and interpreted while families await further evaluation if needed. My hope is that this review will allow providers to be more comfortable with the “norms” of puberty and know when to be concerned or follow more closely.

References

  1. Chemaitilly W, Escobar O, Witchel S. Endocrinology: pubertal development. In: Zitelli BG, McIntire S, Nowalk AJ, eds. Atlas of Pediatric Physical Diagnosis. Philadelphia, PA: Elsevier Saunders; 2012:370–374.
  2. Pediatric Endocrine Society. Delayed puberty in girls: a guide for parents and patients. https://www.pedsendo.org/assets/patients_families/EdMat/first_batch/Delayed%20Puberty%20Girls.pdf. Accessed March 25, 2019.
  3. Pediatric Endocrine Society. Delayed puberty in boys: a guide for parents and patients. https://www.pedsendo.org/assets/patients_families/EdMat/first_batch/Delayed%20Puberty%20Boys.pdf. Accessed March 25, 2019.
  4. Pediatric Endocrine Society. Premature thelarche: a guide for parents and patients. https://www.pedsendo.org/assets/patients_families/EdMat/third_batch/Premature%20Thelarche.pdf. Accessed March 25, 2019.
  5. Bramswig J, Dubbers A. Disorders of pubertal development. Dtsch Arztebl Int. 2009;295–303. doi:10.3238/arztebl.2009.0295 [CrossRef].
  6. Long D. Precocious puberty. Pediatr Rev. 2015;36:319–321. doi:. doi:10.1542/pir.36-7-319 [CrossRef]
  7. Pediatric Endocrine Society. Premature adrenarche: a guide for families. https://www.pedsendo.org/assets/patients_families/EdMat/third_batch/Premature%20Adrenarche.pdf. Accessed March 25, 2019.
  8. Brito VN, Latronico AC. Puberty: when is normal?Arch Endocrinol Metab. 2015;59:93–94. doi:. doi:10.1590/2359-3997000000018 [CrossRef]
  9. American Academy of Pediatrics. Physical development: what's normal? what's not? https://www.healthychildren.org/English/ages-stages/gradeschool/puberty/Pages/Physical-Development-Whats-Normal-Whats-Not.aspx. Accessed March 25, 2019.
  10. Abitbol L, Zborovski S, Palmert M. Evaluation of delayed puberty: what diagnostic tests should be performed in the seemingly otherwise well adolescent?Arch Dis Child. 2016;101:767–771. doi:. doi:10.1136/archdischild-2015-310375 [CrossRef]
  11. Pediatric Endocrine Society. Precocious puberty: a guide for families. https://www.pedsendo.org/assets/patients_families/EdMat/second_batch/Precocious%20Puberty.pdf. Accessed March 25, 2019.
  12. Carel J, Eugster E, Rogol A, et al. Consensus statement on the use of gonadotropin-releasing hormone analogs in children. Pediatrics. 2009;23:e752–e762. doi:. doi:10.1542/peds.2008-1783 [CrossRef]
  13. Li W, Liu Q, Den X, Chen Y, Liu S, Story M. Association between obesity and puberty timing: a systematic review and meta-analysis. Int J Environ Res Public Health. 2017;14:e1266. doi:. doi:10.3390/ijerph14101266 [CrossRef]
  14. Kiess W, Hoppmann J, Gesing J, et al. Puberty—genes, environment, and clinical issues. J Pediatr Endocrinol Metab. 2016;29(11):1229–1231. doi:10.1515/jpem-2016-0394 [CrossRef].

Maturity Rating Scale

Stage Female Male
Breast Pubic Hair Testes Pubic Hair
1 Only the papilla are elevated No sexual hair Testes, scrotal sac, and penis are a size and proportion similar to early childhood No androgen-sensitive hair
2 Breast buds develop, increased diameter of the areolae Sparse growth of long, pigmented, downy hair that may be slightly curled (along the labia) Enlargement of the scrotum and testes with change in scrotal skin Sparse growth of long, pigmented, downy hair that may be slightly curled (at base of penis)
3 Breast and areolae enlarge but show no separation of contour Increased hair growth that is darker, coarser, and curlier; spreads over the junction of the pubes Further growth of penis (length and circumference) as well as testes and scrotum Increased hair growth that is darker, coarser, and curlier; spreads over the junction of the pubes
4 Areolae and papillae elevate above the level of the breasts and form secondary mounds Hair is adult in type but less in volume Penis significantly enlarged and further development of the glans penis; testes and scrotum enlarge and scrotal skin darkens Hair is adult type but less in volume
5 Mature female breasts have developed Hair is an inverse triangle and spreads to the medial surface of the thighs Genitalia are adult in size and shape Hair is an inverse triangle and spreads to the medial surface of the thighs
Authors

Leah Khan, MD

Leah Khan, MD, is a Pediatrician, Park Nicollet Clinics.

Address correspondence to Leah Khan, MD, 300 Lake Drive East, Chanhassen, MN 55317; email: leahdkhan@gmail.com.

Disclosure: The author has no relevant financial relationships to disclose.

10.3928/19382359-20190322-01

Sign up to receive

Journal E-contents