A 15-year-old girl comes to the physician with her father for evaluation of short stature. She feels well overall but is concerned because all of her friends are taller than her. Her birth weight was normal. Menarche has not yet occurred. Her father says he also had short stature and late puberty. The girl is at the 5th percentile for height and 35th percentile for weight. Breast development is Tanner stage 2. Pubic and axillary hair is absent. An x-ray of the left hand and wrist shows a bone age of 12 years. Further evaluation of this patient is most likely to show which of the following sets of laboratory findings?

Low-normal FSH, Low-normal LH, Low Estradiol, Normal Prolactin

High FSH, High LH, Normal Estradiol, Normal Prolactin

Normal FSH, Normal LH, Normal Estradiol, Normal Prolactin

Normal FSH, Normal LH, Low Estradiol, Normal Prolactin

Low FSH, Low LH, Low Estradiol, Normal Prolactin

A 16-year-old teenager presents to the pediatrician with his mother. After she leaves the room he tells the physician that he is worried about puberty. All of his friends have had growth spurts, started building muscle mass, and their voices have changed while he still feels underdeveloped. The physician takes a complete history and performs a thorough physical examination. He goes through the patient’s past medical records and growth charts and notes physical findings documented over the last five years, concluding that the patient has delayed puberty. Which of the following findings supports his conclusion?

The absence of testicular enlargement by age of 14 years

The absence of an adult type of pubic hair distribution by age of 16 years

The absence of linear growth acceleration by age of 13 years

Presence of gynecomastia at age of 15 years

The absence of penile enlargement by age of 12 years

A 15-year-old boy is brought to the physician for a well-child visit. His parents are concerned that he has not had his growth spurt yet. As a child, he was consistently in the 60th percentile for height; now he is in the 25th percentile. His classmates make fun of his height and high-pitched voice. His parents are also concerned that he does not maintain good hygiene. He frequently forgets to shower and does not seem aware of his body odor. As an infant, he had bilateral orchidopexy for cryptorchidism and a cleft palate repair. He is otherwise healthy. Vital signs are within normal limits. On physical exam, axillary and pubic hair is sparse. Genitals are Tanner stage 1 and the testicles are 2 mL bilaterally. Which of the following is the most likely diagnosis?

Constitutional delay of puberty

A 7-year-old girl is brought to the physician because of vaginal bleeding for 2 days. There is no personal or family history of serious illness. She is at the 95th percentile for height and at the 90th percentile for weight. Examination shows enlarged breasts, and the areola and papilla have formed a secondary mound. There is coarse pubic hair that does not extend to the inner thigh. The remainder of the examination show no abnormalities. An x-ray of the left hand and wrist shows a bone age of 11 years. Her serum luteinizing hormone concentration is 0.1 mIU/mL (N < 0.2 mIU/mL). Which of the following is the most appropriate next step in management?

Serum dehydroepiandrosterone level

Delayed puberty — USMLE Lesson

Definition & Thresholds - The Late Bloomers

Delayed puberty is the absence of initial signs of sexual maturation at an age that is 2-2.5 standard deviations above the population mean.

Girls: No thelarche (breast development, Tanner stage 2) by age 13.
Boys: No testicular enlargement (≥4 mL volume or ≥2.5 cm length) by age 14.

Assessment relies on Tanner staging to classify physical development.

⭐ Constitutional Delay of Growth and Puberty (CDGP) is the most common cause, representing a normal variant of development.

Tanner Stages of Pubertal Development

Etiology - Central vs. Peripheral

Delayed puberty results from low sex steroids. The primary defect can be central (hypothalamus/pituitary) or peripheral (gonadal failure).

Hypogonadotropic Hypogonadism (Central)	Hypergonadotropic Hypogonadism (Peripheral)
Defect in GnRH/FSH/LH secretion	Primary gonadal failure
↓ FSH/LH → ↓ Estrogen/Testosterone	↑ FSH/LH → ↓ Estrogen/Testosterone
- Constitutional Delay: Most common overall.	- Turner Syndrome: (45,XO); webbed neck, shield chest.
- Kallmann Syndrome: Defective GnRH neuron migration; associated with anosmia.	- Klinefelter Syndrome: (47,XXY); gynecomastia, tall stature.
- CNS Tumors: e.g., Craniopharyngioma.	- Gonadal Damage: Chemotherapy, radiation.
- Chronic Illness/Malnutrition.

Kallmann Syndrome Diagnostic Algorithm

Clinical Approach - The Puberty Detective

Initial workup is key. A systematic approach differentiates central from peripheral causes.

Step 1: Foundation
- Detailed History: Inquire about chronic illness, nutrition, and anosmia (smell deficit).
- Physical Exam: Tanner staging, height/weight percentiles, dysmorphic features.
- Bone Age X-ray (non-dominant wrist): Crucial first step. Is bone age delayed compared to chronological age?
Step 2: Hormonal Axis
- Measure basal FSH & LH levels.

Tanner Stages of Pubertal Development

⭐ In a patient with delayed puberty and anosmia or hyposmia, always suspect Kallmann Syndrome, a form of central hypogonadotropic hypogonadism due to failed GnRH neuron migration.

Management - Kickstarting the Clock

Constitutional Delay (CDGP):
- Mainstay: Reassurance and observation.
- For psychosocial distress: Short course (4-6 months) of low-dose sex steroids.
  - Boys: Testosterone IM (50-100 mg/month) or oral.
  - Girls: Ethinyl estradiol (2.5-5 mcg/day).
Gonadal Failure (Hypergonadotropic):
- Hormone Replacement Therapy (HRT) to induce and maintain secondary sexual characteristics.
- Girls (Turner’s): Estrogen therapy; progesterone is added later to induce withdrawal bleeding.
- Boys (Klinefelter’s): Testosterone replacement.
Central Causes (Hypogonadotropic):
- Address the underlying pathology (e.g., tumor).
- Fertility induction: Pulsatile GnRH or gonadotropins (hCG, hMG).

⭐ In Turner Syndrome, estrogen is initiated at a low dose around age 11-12 to mimic natural puberty, maximizing adult height potential by delaying epiphyseal fusion.

High‑Yield Points - ⚡ Biggest Takeaways

Delayed puberty is the absence of secondary sexual characteristics by age 13 in girls or 14 in boys.

The most common cause is Constitutional Delay of Growth and Puberty (CDGP), a diagnosis of exclusion.

The first investigation is a bone age X-ray, which is characteristically delayed in CDGP.

Hypogonadotropic hypogonadism (↓FSH/LH) suggests a central cause like Kallmann syndrome (often with anosmia).

Hypergonadotropic hypogonadism (↑FSH/LH) indicates primary gonadal failure (e.g., Turner or Klinefelter syndrome).

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Delayed puberty