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

During the selection of subjects for a study on infantile vitamin deficiencies, a child is examined by the lead investigator. She is at the 75th percentile for head circumference and the 80th percentile for length and weight. She can lift her chest and shoulders up when in a prone position, but cannot roll over from a prone position. Her eyes follow objects past the midline. She coos and makes gurgling sounds. When the investigator strokes the sole of her foot, her big toe curls upward and there is fanning of her other toes. She makes a stepping motion when she is held upright and her feet are in contact with the examination table. Which of the following additional skills or behaviors would be expected in a healthy patient of this developmental age?

Cries when separated from her mother

Responds to calling of own name

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

A 1-year-old male presents to his pediatrician for a well-child visit. Through a history from the mother and physical examination, the pediatrician learns that the baby babbles non-specifically, takes several steps independently, and picks up his cereal using two fingers. His weight is currently 22 lbs (birth-weight 6 lbs, 9 oz), and his height is 30 inches (birth length 18 inches). Are there any aspects of this child's development that are delayed?

There are no developmental concerns

An 8-month-old girl is brought to the emergency department because of fever, vomiting, and diarrhea for 3 days. Her parents report at least 10 watery stools daily. She has had three upper respiratory tract infections since she started daycare 2 months ago, but has otherwise been developing normally. Her mother has a history of celiac disease. The patient is at the 57th percentile for height and the 65th percentile for weight. Her immunizations are incomplete. Her temperature is 38.5°C (101.3°F), pulse is 145/min, and blood pressure is 92/54 mm Hg. Examination shows dry mucous membranes and decreased skin turgor. Bowel sounds are hyperactive. A complete blood count and serum concentrations of glucose, urea nitrogen, and creatinine are within the reference range; there is hypokalemia. In addition to intravenous fluid resuscitation, which of the following is the most appropriate next step in management?

Examination of the stool for ova and parasites

Administration of antidiarrheal medication

Growth charts and interpretation for USMLE Step 2 CK: High-Yield Pediatrics Lessons

Growth Chart Basics - The Pediatric Yardstick

Purpose: Visual tool to assess a child's growth over time against a standardized reference population, using percentile curves.
Charts in India:
- WHO charts: Used for children < 5 years.
- IAP (Indian Academy of Pediatrics) charts: Used for children 5-18 years.
Key Parameters:
- Weight-for-age: Assesses underweight status.
- Height/Length-for-age: Identifies stunting.
- Weight-for-height/Length: Indicates wasting.
- Head Circumference-for-age: Crucial until age 2-3 years.

WHO Growth Chart: Boys Weight-for-Age (Birth to 2 Years)

⭐ Red Flag: Crossing two or more major percentile lines (e.g., 90th, 75th, 50th, 25th, 10th) is more significant than a single low reading and mandates evaluation.

Interpretation - Reading Between the Lines

Trend is Key: A single reading is a snapshot; the curve's trajectory matters most.
Centile Crossing: Crossing >2 major centiles (e.g., 75th to 25th) is a ⚠️ red flag for pathology.
Growth Velocity: The most sensitive indicator. A flattened curve (low velocity) precedes a drop in centiles.
Common Patterns:
- Constitutional Delay: Parallel to lower centiles; bone age < chronological age.
- Familial Short Stature: Parallel to lower centiles; bone age = chronological age.

Finding	Interpretation	Common Causes
Weight↓ first, then Height↓	Wasting (Acute Process)	Inadequate intake, infection, diarrhea
Height↓ first, then Weight↓	Stunting (Chronic Process)	Endocrinopathy, Skeletal dysplasia

Boys: $(Father's Ht + Mother's Ht + 13) / 2$ cm

Girls: $(Father's Ht + Mother's Ht - 13) / 2$ cm

Growth Charts: Patterns of Growth & Causes of Short Stature

Abnormal Patterns - Alarming Curves

Crossing Centiles: A sustained drop crossing ≥2 major centile lines (e.g., 90th → 50th → 25th) is a major red flag.
Flat Trajectory: Growth stagnation (height or weight) for >3-6 months.
Discrepancy: Significant divergence between weight, height, and head circumference (HC) centiles.

Weight-for-age growth chart showing improved growth

⭐ Sequence of Loss in Failure to Thrive (FTT): In nutritional FTT, the first parameter to falter is weight, followed by height, and lastly, head circumference. Head circumference is often spared except in severe, chronic cases.

Catch-down Growth: A normal phenomenon where a large baby (e.g., infant of a diabetic mother) slows their growth rate to settle into their genetic centile.
Catch-up Growth: Rapid growth following a period of illness or malnutrition.

High-Yield Points - ⚡ Biggest Takeaways

Use WHO charts for children < 5 years and IAP charts for 5-18 years.

The growth trajectory is more crucial than a single point measurement.

Crossing two major centiles (e.g., 90th to 25th) is a red flag requiring evaluation.

Weight-for-height is the best indicator for acute malnutrition (wasting).

Height-for-age reflects chronic malnutrition (stunting).

Calculate mid-parental height to assess genetic growth potential.

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