What are the causes of short stature in children and what is the appropriate diagnostic workup?

Short Stature: Causes and Diagnostic Workup

The evaluation of short stature begins by determining whether the child has pathologic or non-pathologic growth, with the most critical initial step being assessment of growth velocity over 4-6 months and calculation of height relative to parental height, as crossing multiple centile lines between ages 3 years and adolescence strongly suggests pathologic disease requiring systematic workup. 1

Definition and Initial Assessment

Short stature is defined as height more than 2 standard deviations below the mean for age and sex (below the 3rd percentile). 1, 2 However, the absolute height measurement alone is insufficient—growth velocity is the single most useful indicator for distinguishing pathologic from non-pathologic causes. 1

Key Initial Measurements Required:

• Serial height measurements over 4-6 months to calculate growth velocity
• Weight and BMI
• Parental heights to calculate midparental height/target height
• Bone age radiograph (left hand and wrist)
• Assessment for centile crossing between ages 3 years and puberty 1

Common pitfall: Healthy large infants often cross centiles in the first 3 years of life to establish their genetic growth curve—this is normal and should not trigger extensive workup. 1

Major Causes of Short Stature

Non-Pathologic Causes (approximately 50% of cases):

Familial Short Stature:

• Early deceleration in linear growth depending on birth measurements
• Normal growth velocity in childhood (4-7 cm/year)
• Normal bone age and pubertal development
• Final adult height short but appropriate for calculated target height 1

Constitutional Delay of Growth and Puberty:

• Deceleration of height in first 3 years
• Normal growth velocity during childhood (4-7 cm/year)
• Delayed bone age and delayed puberty (key distinguishing feature)
• Final adult height within normal range
• Often familial—query parents about their childhood growth patterns 1

Pathologic Causes:

Most Common Pathologic Diagnoses (in order of frequency): 1

1. Chromosome abnormalities (19% of pathologic cases)

   • Turner syndrome and variants (most common)
   • Klinefelter syndrome in tall stature presentations

2. Endocrinopathies:

   • Growth hormone deficiency (29% in some series) 3
   • Hypothyroidism
   • Glucocorticoid excess
   • Multiple hormone resistance (e.g., pseudohypoparathyroidism type 1A) 4

3. Genetic syndromes (14% of cases): 3

   • Noonan syndrome
   • SHOX gene mutations (Leri-Weill syndrome/dyschondrosteosis)
   • Hypochondroplasia
   • Silver-Russell syndrome

4. Chronic systemic diseases:

   • Occult pulmonary, renal, or gastrointestinal disease
   • Inflammatory bowel disease
   • Celiac disease
   • Chronic anemia
   • Malnutrition/psychosocial deprivation 5, 6

5. Intrauterine growth restriction (IUGR)/Small for gestational age (SGA):

   • Defined as length/weight <10th percentile for gestational age
   • Most healthy infants complete catch-up growth by age 2 years
   • Persistent short stature after age 2 suggests pathologic cause 1

6. Idiopathic short stature (ISS): 41% in some series—diagnosis of exclusion 3

Diagnostic Algorithm

Step 1: Differentiate Isolated vs. Associated Findings

Isolated short stature (no dysmorphic features, normal development):

• Consider: familial short stature, constitutional delay, endocrinopathies, Turner syndrome, SHOX mutations, idiopathic short stature 1

Short stature with other abnormalities:

• Proceed to Step 2 to assess body proportions 1

Step 2: Assess Body Proportions

Measure sitting height, arm span, and calculate upper-to-lower segment ratio:

Proportionate short stature with dysmorphic features:

• Consider: chromosome abnormalities, genetic syndromes, inborn errors of metabolism
• Initial testing: Karyotype (girls—rule out Turner syndrome), chromosomal microarray if developmental delay present 1, 6

Disproportionate short stature:

• Skeletal dysplasias
• Initial testing: Skeletal survey, consider genetic panel for skeletal dysplasia genes 1

Step 3: Laboratory Screening (for isolated short stature after excluding familial/constitutional causes)

First-tier screening tests:

• Complete blood count (chronic disease, anemia)
• Comprehensive metabolic panel (renal, hepatic function)
• Thyroid function tests (TSH, free T4)
• Insulin-like growth factor-1 (IGF-1) and IGF binding protein-3
• Erythrocyte sedimentation rate or C-reactive protein (inflammatory conditions)
• Tissue transglutaminase antibodies (celiac disease)
• Urinalysis
• Bone age radiograph 6, 7

Important nuance: Children with genetic diseases have significantly lower deviation from the 3rd percentile (ΔP3) and height standard deviation scores compared to those with idiopathic short stature, but similar values to growth hormone deficiency. 3 This means severe short stature (>3 SD below mean) warrants more aggressive genetic investigation.

Step 4: Genetic Testing (when indicated)

Indications for genetic testing: 5, 3

• Severe short stature (>3 SD below mean)
• Growth hormone deficiency excluded but severe short stature persists
• Dysmorphic features present (even subtle)
• Multiple family members affected
• Consanguinity
• Skeletal abnormalities on radiographs

Testing approach:

• Next-generation sequencing gene panels (104+ genes associated with short stature) have identified causative variants in approximately 30-34% of cases with unknown etiology 5
• Karyotype or chromosomal microarray for suspected chromosomal abnormalities
• SHOX gene testing for familial short stature with subtle skeletal changes (Madelung deformity may not appear until late childhood, especially in males) 1

Critical caveat: Variants of uncertain significance (VUS) are common in genetic testing. Multiple VUS in the same child may have cumulative effects and should not be dismissed. 5 Genetic counseling is essential for interpretation.

Step 5: Specialized Testing (based on clinical suspicion)

• Growth hormone stimulation testing if IGF-1 low and clinical suspicion for GH deficiency
• MRI of pituitary if growth hormone deficiency confirmed 8
• Skeletal survey if disproportionate or skeletal dysplasia suspected
• Whole exome/genome sequencing if panel testing negative but strong suspicion for genetic cause 8

Key Clinical Pearls

Red flags requiring immediate subspecialty referral:

• Crossing multiple centile lines after age 3 years
• Height >3 SD below mean
• Abnormal growth velocity (<4 cm/year in childhood)
• Dysmorphic features or developmental delay
• Signs of chronic disease
• Disproportionate body habitus 1, 6

SHOX gene mutations deserve special attention: They can present as isolated short stature or familial short stature without obvious skeletal changes initially, with frequency ranging from 1.1% to 12.5% in idiopathic short stature depending on selection criteria. Consider skeletal survey even in seemingly isolated familial short stature. 1

Heterogeneity is the rule: Genetic diseases causing short stature show significant phenotypic overlap and variable expression. The same genetic condition can present with vastly different clinical features in different children. 3