Updated: 12/28/2021

Precocious Puberty

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  • Snapshot
    • A 5-year-old boy is referred to the pediatric endocrinology clinic by his pediatrician due to concerns about pubic hair growth. The parents report that he began showing signs of pubic hair growth over the past 3 months, and his height has accelerated markedly in the past half year. At the current visit, his height is at the 99th percentile for height and 98th percentile for weight. Physical examination shows that he has developed pubic hair and has a testicular length of 2.8 cm. A radiograph of his left hand and wrist is obtained and reveals that his bone age is 10 years.
  • Introduction
    • Overview
      • precocious puberty is the appearance of pubertal development in children at a younger age than is considered normal (around 8 years for girls and 9 years for boys)
  • Epidemiology
    • Incidence
      • 1 in 5,000-10,000 children
    • Demographics
      • 10:1 female-to-male ratio
  • ETIOLOGY
    • Pathophysiology
      • onset of puberty is caused by the pulsatile release of GnRH by the hypothalamus ↑ in LH & FSH levels, which stimulate production of sex steroids
        • androgens and estrogens cause the physical changes of puberty in boys and girls, as well as a growth spurt and enlargement of the gonads
      • if child has advanced bone age
        • central precocious puberty
          • high FSH and LH
            • may be caused by CNS tumors
        • peripheral precocious puberty
          • low FSH and LH
            • abnormal secretion of sex hormones from ovaries, testes, or adrenal glands
      • if child has normal bone age
        • isolated premature thelarche
        • isolated premature adrenarche
      • may occur secondary to obesity
  • Presentation
    • History
      • girls
        • breast enlargement
          • may be unilateral enlargement initially
        • appearance of pubic and axillary hair
        • menarche may occur 2-3 years after onset of breast enlargement
        • early pubertal growth spurt
      • boys
        • testicular enlargement, followed by growth of the penis and scrotum
        • pubertal growth spurt occurs later in boys than in girls
    • Physical exam
      • girls
        • breast budding
        • light pink vaginal mucosa
          • color is a deeper red in pre-pubertal girls
        • mild acne
      • boys
        • testicular enlargement (testicular length > 2.5 cm)
        • mild acne
        • facial hair
  • Imaging
    • Radiography of the hand and wrist
      • determine bone age
        • if bone age is within 1 year of child's age, puberty likely has not started
        • if bone age is > 2 years of child's age, puberty has either been present for a year or longer
    • Head MRI
      • may identify an underlying tumor or hamartoma causing central precocious puberty
  • Studies
    • Sex steroid levels
      • DHEA and DHEA-S levels
        • ↑ in boys and girls with premature pubertal onset
      • testosterone levels in boys
        • < 30 ng/dL
          • pre-pubertal
        • 30-100 ng/dL
          • early pubertal
        • 100-300 ng/dL
          • mid-to-late pubertal
        • > 300 ng/dL
          • adult
      • estradiol levels in girls
        • > 20 pg/mL
          • pubertal
            • levels may fluctuate from week to week, so not a consistently reliable indicator
    • LH and FSH levels after GnRH stimulation
      • measure LH and FSH levels after stimulation with GnRH or a GnRH analog
        • ↑ in LH > 8 IU/L is diagnostic of central precocious puberty
        • ↑ in FSH levels > ↑ in LH levels
          • pre-pubertal
  • Differential
    • Premature pubarche
      • key distinguishing factor
        • early appearance of pubic and/or axillary hair but no other signs of puberty and no changes in sex hormones
  • Treatment
    • Medical
      • GnRH analog (i.e., leuprolide) +/- growth hormone
        • follow-up every 4-6 months to assess slowing/arrest of the progression of puberty
          • ↓ acceleration of growth
          • suppression of FSH and LH levels after GnRH challenge
          • ↓ advancement of bone age
    • Surgical
      • resection of CNS tumor if present
        • indications
          • central precocious puberty caused by a CNS tumor
  • Prognosis
    • Majority of girls who experience precocious puberty at ages 6-8 years will achieve an average adult height without treatment
      • extent of improvement in adult height compared with predicted height at start of treatment is correlated with the age of onset of precocious puberty

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