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

Diagnosis: Familial Short Stature

The most likely diagnosis is A - Familial short stature, based on the combination of normal bone age matching chronological age, normal height velocity, consistent tracking below the 5th percentile, and parental heights that predict a short adult stature. 1

Algorithmic Reasoning

Step 1: Rule Out Pathologic Causes

• Normal height velocity is the critical finding that excludes pathologic causes such as growth hormone deficiency, hypothyroidism, and chronic diseases 2
• Growth velocity is the single most useful indicator for distinguishing pathologic from non-pathologic causes of short stature 2, 3
• Pathologic conditions typically present with declining growth velocity and crossing downward through multiple percentile lines after age 3 years 2

Step 2: Differentiate Between Normal Variants

The two main normal variants are familial short stature and constitutional delay of growth, which are distinguished primarily by bone age:

Familial Short Stature:

• Bone age matches chronological age (normal) 1
• Normal growth velocity with consistent tracking along a lower percentile 1, 2
• Predicted adult height is short but appropriate for parental heights 1

Constitutional Delay of Growth:

• Bone age is delayed (younger than chronological age) 1, 3
• Normal or near-normal height velocity during childhood 3
• Delayed puberty with final adult height typically within normal range 1, 3

Step 3: Confirm with Mid-Parental Height Calculation

• Calculate mid-parental target height: [(170 + 157)/2] - 6.5 cm = 157 cm for a boy 1
• This predicted height of approximately 157 cm (5'2") is below the 5th percentile, confirming that the child's short stature is appropriate for genetic potential 1
• The child's consistent tracking below the 5th percentile aligns with this genetic prediction 1

Why Other Options Are Incorrect

Constitutional Short Stature (Option B): Excluded because bone age is normal and matches chronological age, whereas constitutional delay characteristically shows delayed bone age 1, 3

Hypothyroidism (Option C): Excluded because hypothyroidism causes declining growth velocity and crossing downward through percentile lines, not normal velocity with consistent tracking 2, 4

Growth Hormone Deficiency (Option D): Excluded because GHD presents with abnormal (declining) growth velocity, whereas this patient has normal height velocity 2, 5

Management Approach

• Reassurance is the appropriate management, with no endocrine intervention indicated 1
• Continue monitoring growth velocity every 3-6 months to ensure it remains normal 1, 2
• Provide psychological support for the child and family regarding height expectations 1
• Expected adult height will match genetic potential based on parental heights 1

Critical Pitfall to Avoid

Do not order unnecessary endocrine testing (thyroid function, IGF-1, growth hormone stimulation tests) when bone age is normal and growth velocity is normal, as this represents a normal variant requiring only observation 1, 6