Overview
Definition:
Short stature is defined as a height more than 2 standard deviations below the mean for age and sex, or below the third percentile
It represents a failure to achieve genetic potential height
Accurate assessment involves evaluating growth velocity, genetic potential, and skeletal maturation.
Epidemiology:
Affects approximately 3% of the pediatric population
The etiology is diverse, ranging from benign variants (familial short stature, constitutional delay of growth and puberty) to pathological conditions (endocrine disorders, genetic syndromes, chronic illnesses, skeletal dysplasias).
Clinical Significance:
Identifying the cause of short stature is crucial for timely intervention, preventing long-term physical and psychosocial morbidity, and optimizing adult height
Early diagnosis and treatment can significantly improve outcomes for conditions like growth hormone deficiency and hypothyroidism.
Midparental Height
Calculation:
Midparental height (MPH) estimates the target adult height based on parental heights
For boys: (Father's height + Mother's height + 13 cm) / 2
For girls: (Father's height + Mother's height - 13 cm) / 2
A standard deviation range (e.g., ± 8.5 cm) around the MPH provides a predicted adult height range.
Interpretation:
A child's height falling within ± 8.5 cm of the MPH is generally considered within normal genetic potential
Significant deviation suggests potential growth disorders, nutritional deficiencies, or chronic illnesses impacting growth.
Limitations:
MPH does not account for precocious puberty, delayed puberty, or chronic diseases that may affect final adult height
It serves as a baseline for genetic potential, not a definitive predictor of final height alone.
Bone Age Assessment
Definition:
Bone age (BA) represents the developmental or skeletal maturity of an individual, assessed by radiographic examination of the bones, typically the hand and wrist
It reflects the epiphyseal fusion status, which is influenced by hormones and overall health.
Methodology:
The most common method is the Greulich and Pyle (G&P) atlas, which compares the child's skeletal maturation to standard X-rays
The Tanner-Whitehouse (TW2 or TW3) method is more detailed, scoring individual bone development
Radiographs of the left hand and wrist are standard.
Interpretation:
A bone age equal to chronological age (CA) suggests normal skeletal maturation
BA significantly delayed relative to CA (e.g., >2 years) may indicate constitutional delay of growth and puberty, hypothyroidism, or GH deficiency
BA significantly advanced relative to CA may suggest precocious puberty or overexposure to exogenous steroids.
Diagnostic Approach
History Taking:
Detailed birth history (gestational age, birth weight, length)
Growth history (serial height measurements, growth charts)
Nutritional status
History of chronic illnesses (GI, renal, cardiac, pulmonary)
Pubertal development (age of onset of secondary sexual characteristics)
Family history of growth problems or endocrine disorders
Medications (steroids)
Social and emotional factors.
Physical Examination:
Accurate anthropometric measurements (height, weight, head circumference)
Assess proportionality
Examine for dysmorphic features
Assess Tanner stage of puberty
Palpate thyroid
Check for signs of rickets or other skeletal abnormalities
Assess for signs of chronic disease
Fundoscopic examination.
Investigations:
Baseline laboratory tests: Complete blood count, ESR, CRP, electrolytes, BUN, creatinine, calcium, phosphate, alkaline phosphatase, liver function tests, urinalysis
Endocrine evaluation: Thyroid function tests (TSH, free T4), IGF-1, IGFBP-3
Consider GH stimulation tests if indicated
Karyotype if genetic syndrome suspected
Skeletal survey if multiple bone lesions are suspected
Imaging: Bone age radiograph of the hand and wrist is essential
Other imaging may be needed based on suspected etiology (e.g., renal ultrasound, cardiac echo).
Differential Diagnosis:
Constitutional delay of growth and puberty (CDGP)
Familial short stature (FSS)
Growth hormone deficiency (GHD)
Hypothyroidism
Cushing's syndrome
Rickets
Malnutrition
Chronic diseases (e.g., inflammatory bowel disease, celiac disease, renal failure)
Genetic syndromes (e.g., Turner syndrome, Noonan syndrome, Down syndrome)
Skeletal dysplasias (e.g., achondroplasia)
Intrauterine growth restriction (IUGR) with failure to catch up.
Management Principles
Addressing Underlying Cause:
Treatment is directed at the specific etiology
For hypothyroidism, thyroid hormone replacement
For GH deficiency, recombinant human growth hormone (rhGH) therapy
For nutritional deficiencies, nutritional support and supplementation
For chronic illnesses, optimizing management of the primary condition.
Growth Hormone Therapy:
Indicated for idiopathic short stature (ISS) and confirmed GH deficiency
Dosage is typically 0.2-0.3 mg/kg/week divided into daily subcutaneous injections, adjusted based on IGF-1 levels and growth response
Requires regular monitoring of height velocity and IGF-1 levels.
Constitutional Delay Of Growth And Puberty:
Often requires no specific treatment
reassurance and monitoring are key
In selected cases, a trial of low-dose sex hormones can accelerate growth and induce puberty if psychosocial concerns exist.
Supportive Care:
Psychosocial support is vital for children with short stature
Nutritional counseling
Regular follow-up to monitor growth and treatment efficacy
Educational support to address any academic challenges.
Key Points
Exam Focus:
Understand the calculation and interpretation of midparental height
Know the methods and interpretation of bone age assessment (G&P, Tanner-Whitehouse)
Recognize indications for GH therapy and common etiologies of short stature.
Clinical Pearls:
Always plot serial height measurements on appropriate growth charts
A falling growth curve is more concerning than a single low height measurement
Differentiate between familial short stature and constitutional delay from pathological causes.
Common Mistakes:
Over-reliance on MPH without considering bone age or growth velocity
Initiating GH therapy without confirmed diagnosis of GH deficiency or significant short stature
Failing to investigate for underlying chronic illnesses or endocrine disorders.