Diagnosis: Familial Short Stature
This child has familial short stature, characterized by consistently low height percentile with normal growth velocity, normal bone age matching chronological age, and parental heights that predict short adult stature within the genetic potential. 1, 2
Key Diagnostic Features Supporting Familial Short Stature
The clinical presentation demonstrates the classic triad that distinguishes familial short stature from other causes:
- Normal growth velocity during childhood (typically 4-7 cm/year), which excludes pathologic causes like growth hormone deficiency or hypothyroidism 1
- Normal bone age matching chronological age, which is the critical feature that differentiates this from constitutional delay of growth 1, 2
- Parental heights consistent with genetic potential: Father 170 cm and mother 155 cm predict a mid-parental target height that would place this child in the lower percentiles 2, 3
Why Other Diagnoses Are Excluded
Constitutional Delay of Growth (Option D) - Excluded
Constitutional delay presents with delayed bone age (younger than chronological age), delayed pubertal development, and eventual adult height within normal range. 1, 4 This child has normal bone age, which definitively rules out constitutional delay. 2
Growth Hormone Deficiency (Option C) - Excluded
Growth hormone deficiency would present with abnormal (decreased) growth velocity and crossing downward through multiple percentile lines after age 3 years. 1 This child maintains consistent growth along the same percentile, indicating normal growth velocity. 5
Hypothyroidism (Option A) - Excluded
Hypothyroidism causes pathologic short stature with decreased growth velocity and delayed bone age. 1 The normal growth velocity and normal bone age exclude this diagnosis. 1
Clinical Approach and Management
Familial short stature requires reassurance rather than intervention, as the predicted adult height will be short but appropriate for the genetic potential based on parental heights. 2
Confirming the Diagnosis
Calculate mid-parental target height: [(father's height + mother's height)/2] ± 6.5 cm depending on child's sex. 2 For this family, the calculation would predict adult height in the lower percentiles, consistent with the child's current growth pattern.
Important Caveats
- Continue monitoring growth velocity to ensure it remains normal (4-7 cm/year in childhood). 1, 2
- If growth velocity decreases or the child crosses downward through multiple percentile lines after age 3, reassess for pathologic causes. 1
- Children more than 3 standard deviations below the mean (well below 1st percentile) have higher likelihood of underlying pathology and warrant more extensive evaluation. 5, 6
No Endocrine Intervention Indicated
Growth hormone therapy is not indicated for familial short stature, as the child's growth pattern reflects normal genetic variation rather than hormone deficiency. 2 The expected adult height will match genetic potential regardless of intervention.
Answer: b- familial short stature