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 6-year-old girl is brought to the pediatrician by her father for an annual physical examination. The father reports that the patient is a happy and healthy child, but he sometimes worries about her weight. He says that she is a “picky” eater and only wants chicken nuggets and French fries. He also notes some mild acne on her cheeks and forehead but thinks it’s because she “doesn’t like baths.” The father says she has met all her pediatric milestones. She has recently started kindergarten, can tell time, and is beginning to read. Her teacher says she gets along with her classmates well. The patient was born at 38 weeks gestation. She has no chronic medical conditions and takes only a multivitamin. Height and weight are above the 95th percentile. Physical examination reveals scattered comedones on the patient’s forehead and bilateral cheeks. There is palpable breast tissue bilaterally with raised and enlarged areolae. Scant axillary hair and coarse pubic hair are also noted. A radiograph of the left hand shows a bone age of 9 years. Serum follicular stimulating hormone (FSH) level is 9.6 mU/mL (normal range 0.7-5.3 mU/mL) and luteinizing hormone (LH) level is 6.4 mU/mL (normal range < 0.26 mU/mL). Which of the following is the most appropriate diagnostic test?

Brain magnetic resonance imaging (MRI)

Dehydroepiandrosterone sulfate levels

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

Tall stature evaluation for USMLE Step 1: High-Yield Pediatrics Lessons

Tall Stature - Sizing Up Giants

Definition: Height > 97th percentile or > 2 SD above the mean for age and sex.
Initial Workup: Assess growth velocity, calculate mid-parental height (MPH), and determine bone age.

Sotos Syndrome: Clinical Features and Skeletal Changes

⭐ Sotos Syndrome (Cerebral Gigantism): A key differential, presents with a triad of overgrowth (height/head circumference >97th percentile), intellectual disability, and distinct craniofacial features. Caused by NSD1 gene mutation.

Etiology - Genes, Glands, & Growth

Familial Tall Stature (Constitutional)
- Most common cause; a variant of normal growth.
- Growth velocity is normal, follows a consistent percentile curve.
- Bone Age (BA) ≈ Chronological Age (CA).
- Mid-parental height is in the tall range.
Endocrine Causes (Hormonal Imbalance)
- GH Excess (Pituitary Gigantism): Rare. ↑ Growth velocity, acromegalic features.
- Precocious Puberty: Early growth spurt but premature epiphyseal fusion leads to ↓ final adult height.
- Hyperthyroidism: ↑ Metabolic rate and growth rate.
Genetic & Syndromic Overgrowth
- Marfan Syndrome: Connective tissue disorder (FBN1 gene). Features: arachnodactyly, ectopia lentis, aortic dilatation.
- Klinefelter Syndrome (XXY): Tall, eunuchoid proportions, gynecomastia.
- Sotos Syndrome: Cerebral gigantism, prominent forehead, advanced BA.
- Beckwith-Wiedemann Syndrome: Macroglossia, omphalocele, hemihypertrophy.

Clinical features of Marfan syndrome

⭐ The most common cause of a child presenting with tall stature is familial (constitutional) tall stature, where the growth pattern is consistent with the genetic potential of the parents.

Workup - The Detective Work

Initial Steps:
- Detailed History: Familial height (mid-parental height), growth velocity.
- Thorough Physical Examination: Dysmorphic features, puberty staging (Tanner).
- Bone Age (BA): Left hand & wrist X-ray (Greulich-Pyle atlas).

AI-supported pediatric bone age and height estimation

⭐ Klinefelter Syndrome (47,XXY) is a classic cause of eunuchoid tall stature with delayed puberty and normal bone age.

High‑Yield Points - ⚡ Biggest Takeaways

Familial Tall Stature is the most common cause; Mid-Parental Height (MPH) calculation is the crucial first step.

Bone age is the single most useful investigation to differentiate causes.

Suspect Klinefelter Syndrome (XXY) in tall boys with small testes and learning difficulties.

Marfan Syndrome features arachnodactyly, upward lens dislocation, and aortic root dilatation.

Homocystinuria mimics Marfan but has intellectual disability and downward lens dislocation.

Sotos Syndrome presents with macrocephaly and advanced bone age.

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