What is the initial evaluation and treatment approach for a 14-year-old boy with short stature?

Initial Evaluation of Short Stature in a 14-Year-Old Boy

Begin by plotting serial height measurements on growth charts, calculating growth velocity over 6+ months, determining bone age via left wrist radiograph, and calculating midparental target height to differentiate pathologic from non-pathologic causes. 1, 2

Step 1: Assess Growth Pattern and Velocity

• **Document current height and compare to <3rd percentile threshold** (height >2 SD below mean for age defines short stature) 3, 4
• Calculate growth velocity over at least 6 months—normal childhood velocity is 4-7 cm/year; crossing multiple centile lines between ages 3-14 years strongly suggests pathologic etiology 3
• Obtain bone age (left wrist radiograph) to assess growth potential and distinguish constitutional delay (delayed bone age) from familial short stature (normal bone age) 1, 2
• Calculate midparental target height: [(mother's height + father's height)/2] ± 6.5 cm for boys to determine genetic potential 1

Step 2: Differentiate Isolated vs. Syndromic Short Stature

Perform detailed physical examination specifically looking for:

• Dysmorphic features suggesting chromosomal abnormalities or genetic syndromes (Turner syndrome most common pathologic diagnosis in genetic evaluations) 3, 1
• Body proportions (sitting height/standing height ratio, arm span) to identify disproportionate short stature suggesting skeletal dysplasia 3
• Signs of endocrinopathy: hypothyroid features, cushingoid appearance, signs of hypopituitarism 3
• Pubertal staging at age 14—delayed puberty with delayed bone age suggests constitutional delay 3

Step 3: Initial Laboratory Screening

Order the following baseline tests:

• Complete blood count to screen for chronic disease/malnutrition 2
• Comprehensive metabolic panel including renal and liver function 2
• Thyroid function tests (TSH, free T4)—hypothyroidism is a common treatable cause 3, 2
• IGF-1 and IGFBP-3 as screening for growth hormone deficiency 2
• Celiac screening (tissue transglutaminase antibodies) as celiac disease is a common occult cause 5

Step 4: Determine Specific Etiology

If Isolated Short Stature with Normal Velocity:

• Constitutional delay of growth and puberty: delayed bone age (>2 years behind chronological age), delayed puberty, family history of late bloomers, normal final adult height expected 3
• Familial short stature: normal bone age, normal pubertal timing, projected adult height consistent with short parental heights 3
• SHOX gene mutations: consider testing if subtle skeletal changes present (Madelung deformity, mesomelia) even in males where findings may be subtle at age 14 3

If Pathologic Features Present:

• Growth hormone deficiency: perform GH stimulation testing if IGF-1 low, poor growth velocity, or clinical suspicion 2
• Turner syndrome variants: karyotype analysis mandatory in ALL girls with unexplained short stature (most common pathologic diagnosis) 3, 1
• Chronic systemic disease: inflammatory bowel disease, celiac disease, chronic kidney disease 5

Step 5: Advanced Imaging When Indicated

• Skeletal survey if disproportionate short stature or height >3 SD below mean to evaluate for skeletal dysplasia 3, 1
• MRI pituitary if GH deficiency confirmed or multiple pituitary hormone deficiencies suspected 2
• Chromosomal microarray if dysmorphic features present but karyotype normal 3, 1

Step 6: Referral Criteria

Refer to pediatric endocrinology if:

• Severe growth velocity deceleration (crossing centile lines) 1
• Height >3 SD below mean (higher likelihood of pathology) 4
• Confirmed or suspected GH deficiency requiring stimulation testing and potential treatment 1, 6
• Idiopathic short stature where GH therapy consideration needed (height SDS ≤-2.25 with growth rates unlikely to permit normal adult height) 6

Critical Pitfalls to Avoid

• Missing Turner syndrome in phenotypically normal girls—always obtain karyotype in girls with unexplained short stature 1, 2
• Assuming familial short stature without calculating midparental height—may miss pathologic causes 1
• Failing to obtain bone age—essential for distinguishing constitutional delay from other etiologies 1, 2
• Overlooking celiac disease—common occult cause with minimal GI symptoms 5
• Not reviewing birth measurements—intrauterine growth restriction suggests different diagnostic pathway 3, 2

Treatment Considerations

If GH deficiency confirmed, recombinant GH therapy dosing for pediatric GHD is up to 0.3 mg/kg/week divided into daily subcutaneous injections (up to 0.7 mg/kg/week in pubertal patients) 6. Treatment should continue until epiphyseal closure or growth velocity <2 cm/year 2, 6.