Causes of Growth Disorders

Causes

Short stature is defined as being below the 3rd percentile on the standard growth chart for the same age and sex. In other words, it refers to a child whose height is among the shortest 3 out of 100 children of the same sex and birthdate.

1. Normal-variant short stature (normally short stature)

This is the most common reason among children who visit the hospital because they are short. There is no disease, but it refers to cases in which height is short due to genetic tendencies and constitutional factors. It includes familial short stature and constitutional growth delay.

1. Familial short stature

Familial short stature is the most common cause of short stature. If the parents are short, the child’s height is also short due to genetic influence. Growth rate and puberty begin at the normal time, and bone age also matches chronological age. However, the final adult height falls within the height inherited from the parents.

2. Constitutional growth delay

Constitutional growth delay means that growth is delayed due to constitutional factors. The current height is short, but puberty appears late, so growth continues later, and the final adult height reaches the normal range. Bone age is delayed compared with chronological age, and pubertal development in both girls and boys is delayed by about 2 to 3 years. There is also a family history of delayed puberty in the parents. If the mother had a late menarche or the father had a late beard growth, it is often the case that the parents, siblings of the parents, or grandparents went through puberty late and were short when young but grew later. This is more common in boys than in girls and can be easily identified by confirming a normal growth rate and performing a bone age test.

3. Idiopathic short stature

In some children with short stature, no clear cause can be found even after diagnostic testing. Idiopathic short stature is defined as a heterogeneous group of short stature in which height is below the 3rd percentile and no systemic disease, nutritional disorder, endocrine disease, or organ disorder including chromosomal abnormalities can be found. Idiopathic short stature generally refers to cases with normal birth weight and no abnormality in growth hormone secretion. Idiopathic short stature also includes familial short stature and constitutional growth delay. Growth hormone neurosecretory dysfunction, growth hormone receptor abnormalities, defects in post-receptor growth hormone responses, and some gene abnormalities including the SHOX gene have been reported, but in general there are difficulties with testing.

2. Growth disorder due to disease (disease-related short stature)

1. Primary growth disorder (intrinsic disorder)

(1) Cartilage and bone disorders

① Achondroplasia

The growth plate, which is most important for bone growth, is made of cartilage. Achondroplasia is a disease in which cartilage is not formed properly. In patients with achondroplasia, long bones do not grow, so the arms and legs are short while the trunk is of normal length. They also have characteristic features such as a large head, a flat bridge of the nose, a small nose, and a large forehead.

② Hypochondroplasia

This condition is milder than achondroplasia, and because the face looks normal, it is often considered to be a very short normal person. In such cases, the final adult height is about 145 to 160 cm for men and about 135 to 150 cm for women. It is inherited as an autosomal dominant trait and occurs due to a mutation in the same gene as achondroplasia.

(2) Chromosomal abnormalities

① Turner syndrome

Normally, girls have two X chromosomes, but when one of the X chromosomes is missing or partially missing, Turner syndrome occurs. It affects 1 in every 4,000 female births. Most have normal intelligence, but they show short stature, puffy hands and feet at birth, a short neck, a broad chest, small nipples, and characteristic facial features.

② Down syndrome

Down syndrome is a syndrome in which there are more than the normal number of chromosome 21 copies. In addition to short stature, it is associated with intellectual disability. Hypothyroidism may occur and can cause growth delay and developmental delay, so it is important to detect and treat it.

(3) Small for gestational age (intrauterine growth restriction)

When the birth weight during the corresponding pregnancy period is below the 3rd percentile, it is called small for gestational age or intrauterine growth restriction. In general, in term deliveries, if the newborn’s length at birth is less than 45 cm or the weight is 2.5 kg, it can be considered small for gestational age.

(4) Other syndromes

① Silver-Russell syndrome

② Noonan syndrome

2. Secondary growth disorder (extrinsic disorder)

This refers to short stature caused by external factors, and if the cause is corrected, normal growth can be restored.

(1) Nutritional deficiency

Nutrition is the next most important factor for height growth after genetics. Contributing factors should be identified and corrected.

① Malabsorption of food

② Inadequate nutritional intake during the growth period

③ Children taking psychiatric medication

(2) Chronic psychiatric illness

(3) Endocrine diseases

① Growth hormone deficiency

② Hypothyroidism

③ Precocious puberty

④ Cushing syndrome

(4) Psychological or environmental causes

So far, we have explained the causes of growth disorders.

In the next part, we will look at the diagnosis of growth disorders.

Source: Korea Disease Control and Prevention Agency, National Health Information Portal