What is the likely diagnosis for a 10-12 year old pediatric patient with short stature, below 5th percentile, normal height velocity, and normal bone age, with a family history of short stature (father's height 170 cm, mother's height 157 cm)?

Familial Short Stature

This child has familial short stature, not constitutional delay, because the bone age is normal (matches chronological age) and the mid-parental target height predicts short adult stature consistent with the family pattern. 1

Key Distinguishing Features

The critical differentiating factor between these two benign variants is bone age:

• Familial short stature: Normal bone age, normal growth velocity, early deceleration in linear growth (if born at normal size), and predicted adult height that is short but appropriate for parental heights 1
• Constitutional delay: Delayed bone age, normal growth velocity, delayed puberty, with final adult height typically within normal range 1, 2

Clinical Reasoning for This Case

Growth pattern analysis:

• Height consistently below 5th percentile indicates true short stature 1, 3
• Normal height velocity (4-7 cm/year in childhood) rules out pathologic causes 1
• Normal bone age matching chronological age excludes constitutional delay 1, 2, 4

Family history calculation:

• Father: 170 cm, Mother: 157 cm
• Mid-parental target height = [(170 + 157)/2] - 6.5 cm = 157 cm for a boy (approximately 5th-10th percentile) 1
• The child's growth trajectory aligns with genetic potential, confirming familial pattern 1

What Makes Constitutional Delay Different

Constitutional delay would present with:

• Deceleration in first 3 years of life 1, 2
• Delayed bone age (younger than chronological age) 1, 2, 4
• Delayed pubertal development 1, 2
• Family history of late bloomers 1
• Predicted adult height within normal range despite current short stature 2

Clinical Pitfalls to Avoid

Do not miss pathologic causes in children below 5th percentile:

• Always verify growth velocity over 4-6 months to ensure it remains normal (not decelerating) 1, 5
• Screen for Turner syndrome in girls with short stature, even without obvious dysmorphic features 5, 4
• Consider SHOX gene mutations if any skeletal abnormalities present (subtle Madelung deformity, mesomelia) 1, 5
• Evaluate for growth hormone deficiency or hypothyroidism if growth velocity is abnormal 5, 4

Bone age is the decisive test in this clinical scenario:

• Normal bone age + normal growth velocity + short parental heights = familial short stature 1, 4
• Delayed bone age + normal growth velocity + family history of late puberty = constitutional delay 2, 4

Management Implications

Reassurance is appropriate for familial short stature:

• No endocrine intervention indicated 1
• Expected adult height will match genetic potential (short but healthy) 1
• Continue monitoring growth velocity to ensure it remains normal 1, 5
• Provide psychological support for child and family regarding height expectations 5