Short Stature in Children

Definition Of Short Stature

There are two definitions of short stature as follows.

Based on the centile chart, a child is said to have short stature if its height for age is below the third centile. According to the chart based on standard deviation, a child is said to exhibit short stature if its height for age lies below the -2 standard deviation of the population mean.

• Charts For The Reference Of Height For Age
  • They are groups of the graphs of standard heights plotted against corresponding ages.
  • One group gives a centile chart; the other is called a chart based on standard deviation.
  • WHO recommends the colour code: Blue for male children and pink for female children.

Types Of Short Stature Based On Cause

• Broadly, there are two types of short stature: physiological and pathological.
• Physiological Short Stature
  • Physiological short stature is a condition that does not involve an underlying disease.
  • Children with this type have normal growth velocity, which means the rate of height gain is the same as that of a child with a normal age for height.
  • The height plot against the age of children with short physiological stature runs parallel to the growth curve. 
  • There are two types of short physiological stature.
    • Constitutional delay in growth
    • Familial short stature
• Pathological Short Stature
  • It results from an underlying disease.
  • Children with pathological short stature have decreased growth velocity, implying that their height gain rate is significantly lower than that of normal children.
  • The causes of pathological short stature are as follows. 

• Nutritional causes: Protein-energy malnutrition is the most common cause of pathological short stature.
• Chronic diseases: Multiple chronic disorders include cystic fibrosis, severe asthma, celiac disease, and congenital heart diseases.
• Endocrine disorders: The most common endocrine disorders include hypothyroidism, growth hormone deficiency, and Cushing’s syndrome
• Syndromes: Down syndrome, turner syndrome, and Prader-Willi syndrome are the common syndromes that cause short stature.
• Skeletal dysplasias: Achondroplasia is the most common, resulting in short stature.
• IUGR(Intra Uterine Growth Retardation): IUGR can cause Primordial Dwarfism.
• Psychosocial factors: They include poverty, child abuse, and overcrowding.

Types of Short Stature Based on Body Proportions

• Based on body proportion, short stature is of two types: proportionate and disproportionate short stature.
• Body proportion refers to the ratio of the length of the upper body to that of the lower body. 
• The upper segment extends from the tip of the head to the midpoint of the pubic symphysis, whereas the lower segment is the body below the pubic symphysis.
• The ratio of the upper body to the lower body begins at 1.7 to 1.9 at birth and reduces to 1 until 8-10.

Proportionate Short Stature

• In this type, the upper-to-lower body ratio is appropriate for age, but the overall height for age is low. 
• Causes of proportionate short stature include
  • Constitutional delay in growth
  • Familial inheritance
  • Malnutrition(except rickets)
  • Chronic illness
  • Growth hormone deficiency

Disproportionate Short Stature

• Disproportionate short stature is of two types: Short limbed short stature and short trunk short stature. 

Short-Limbed Short Stature

• Short-limbed short stature refers to short stature due to short limbs, which reflects a greater ratio of the upper body to the lower body than expected for age.
• The common causes of short-limbed short stature are
  • Rickets
  • Achondroplasia
  • Hypothyroidism
  • Turner syndrome

Short Trunk, Short Stature

• This type refers to short stature due to a shorter trunk, which reflects a lower-than-expected ratio of the upper body to the lower body for age.
• Common causes of this type are
  • Mucolipidosis
  • Morquio disease: a type of mucopolysaccharidosis
  • Vertebral anomalies such as hemivertebrae
  • Caries spine or tuberculosis of the spine
  • Spondyloepiphyseal dysplasia

 Investigations For Short-Stature

There are three levels of investigation. 

Approach To The Etiological Work Up In Short Stature

• Normal growth velocity and a height between -2 and -3 standard deviation are considered for short physiological stature.
• If chronological age is more than bone age, and bone age is equal to height age, the diagnosis should be the constitutional delay in growth.
• If chronological age is equal to bone age, but both exceed height age, the diagnosis should be short familial stature.
• When a child has a low growth rate and height for age is lower than -3 standard deviation, it is pathological short stature.
• If the patient has dysmorphism or an altered upper segment-to-lower segment ratio, it indicates a syndrome or related condition.
• If the patient has normal facies and an upper-segment to lower-segment ratio, level-wise investigations are performed. Level 1, level 2, and level 3 investigations are done. If the investigations cannot be concluded, idiopathic and growth hormone therapy can be attempted.

Also Read: Rapid Acquisition Of Key Concepts- Growth And Development

Individual Causes of Short Stature

1. Constitutional Delay in Growth
   • It is the overall most common cause of short stature in children.
   • The children grow normally until they are 6 to 12 months old. Their growth slows down for a variable period between one and three years of age.
   • When the child gets medical attention, the growth rate returns to normal, and the plot runs parallel to the growth curve, but the adult height does not rise above the third centile.
   • Children with constitutional delays in growth have better outcomes than those with other etiologies.
   • Other manifestations include
     • The delayed onset of puberty and pubertal growth spurt occurs at the age of 15 or 16, as opposed to the normal age of 12-13. Once they attain puberty, they gain height rapidly. Most of them have better adult height, usually above the -2 standard deviation.
     • In kids with constitutional delay in growth, the serum level of IGF-1 is low for chronological age but normal for bone age and height age.
2. Familial Short Stature
   • Children with short familial stature have the following clinical features.
     • Borderline birth weight and height.
     • The decreased growth rate in infancy
     • Chronological age corresponds with bone age, but both exceed height age.
     • The normal time of puberty and pubertal growth spurt
     • Lower overall adult height but appropriate for target height according to the parent's height.
3. Psychosocial Dwarfism
   • It is also known as emotional deprivation, maternal deprivation, or hyperphagic deprivation-related dwarfism.
   • Low levels of IGF-1 due to emotional stress related to neglect, abuse, overcrowding, and poverty are the causes.
   • If given emotional attention, the child may recover the growth rate.
4. Primordial Dwarfism
   • It can be either non-syndromic or syndromic form.
   • It is related to severe forms of IUGR in utero.
     • Non-syndromic form: Severe intrauterine growth restriction leads to loss of cells during pregnancy, which results in short stature in later stages.
     • Syndromic form: The most common syndromic form is Silver-Russell syndrome. In addition to short stature, children born with Silver-Russell syndrome exhibit silvery hair, triangular face, receding chin, and mental abnormalities.
5. Hormonal Causes of Short Stature in Children
   • The most common hormonal cause is hypothyroidism. The other causes include:
     • Growth hormone deficiency
     • Cushing syndrome
     • Pseudohypoparathyroidism
     • These abnormalities significantly reduce growth rate and delay bone age compared to chronological age.

Management of Short Stature in Children

• Broadly, management is of two types. General measures and specific measures
• General measures include the following strategies.
  • Monitoring of the child's nutritional status, increasing caloric and protein input according to the child's needs.
  • Zinc supplementation plays an important role in mitigating short stature. A low dose of 10mg/day for three to six months has been found to help individuals with idiopathic short stature. The supplementation can be given as zinc gluconate, acetate, or carbonate.
• Specific management include
  • Treating underlying chronic diseases
  • Hormone replacement before irreversible changes occur.
  • Limb lengthening procedures benefit patients with delayed presentation, dysplasia, achondroplasia, and amelias. They are performed in older children. They include orthopedic procedures that involve fixators, such as Ilizarov or linear rail fixators.

Growth Hormone Therapy in Short Stature

Indications for Growth Hormone Therapy

• Growth hormone deficiency is a rare cause of short stature, and numerous factors influence height gain. Hence, hormone replacement must be considered as specified indications as follows:
  • Growth hormone deficiency
  • Idiopathic short stature with low growth velocity
  • Turner syndrome
  • Noonan syndrome
  • Prader-Willi syndrome
  • Primordial dwarfism and Russel-Silver syndrome if fail to catch up by 3 years of age.
  • Chronic renal insufficiency
  • SHOX gene mutations
  • Leri-Weill dyschondrosteosis

Dose and Regimen

• Optimally, it should be started before the child turns 11 years. However, it may work effectively in older children.
• The preparation used is recombinant human growth hormone, denoted as rHGH.
• The route of administration is subcutaneous, preferably at night.
• The standard dose of the hormone is 25-50 micrograms/Kg/day or 0.03-0.1 IU/Kg/day.
• The dose monitoring is based on IGF- levels.
• The expected overall improvement in height is 20-30 cm from pretreatment levels.
• The therapy has a maximum effect (50%) in the first year, and the height growth achieved ranges from 10 to 15 cm.
• In subsequent years, the rate of growth observed is 5-6 com per year.

Criteria to Stop Growth Hormone Therapy

• The effect of growth hormone therapy diminishes with time and developmental changes in the body. The following are the criteria to stop the therapy.
  • Decrease growth rate to less than 2.5 cm per year in response to optimal dose.
  • Bone age >14 years in girls and >16 years in boys.

Side Effects of Growth Hormone Therapy

• The potential adverse effects of growth hormone therapy are as follows.
  • Pseudotumor cerebri
  • Gynecomastia
  • Slipped capital femoral epiphysis
  • Scoliosis
  • Type-2 diabetes only, not type-1
  • Reversible hypothyroidism
• The risk of malignancy is not significantly increased. However, the therapy increases the risk of recurrence for children with a history of malignancy. Hence, the risk and benefit ratio will be analyzed before the therapy.

Also Read: NEET SS Pediatrics Growth and Development Questions

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