Brief overview
- Course of disease and prognosis: Depends on the cause of short stature, in many cases normal life expectancy
- Symptoms: Dependent on the cause, usually none apart from the shorter height, joint and back pain in achondroplasia
- Causes and risk factors: Various causes, malnutrition or malnutrition affect growth
- Diagnosis: Based on detailed discussions, measurement of height, X-ray examination, physical examination, laboratory tests, molecular genetic tests
- Treatment: Often not possible, treatment of the underlying disease, sometimes with artificial growth hormones
- Prevention: Depending on the cause, not preventable, otherwise sufficient and balanced diet, healthy social environment
What is short stature?
Short stature is either present at birth or develops later as a result of growth that is too slow or ends too early. Those affected tend to reject the term “short stature” as it has a discriminatory undertone. This is why it is gradually disappearing from the language.
At what height are you short?
Short stature is often a temporary phenomenon. Some babies and toddlers are temporarily considered short; some catch up again and are of normal height in adulthood.
How does normal growth work?
A person grows from the moment of conception – first in the mother’s womb and after birth until the end of the growth phase. In girls, this usually ends around the age of 16, in boys about two years later. It is possible to grow for a few more years after this, but then usually only slightly.
A person grows the most in the first few years of life:
- About 25 centimeters in the first year
- About eleven centimeters in the second year of life
- About eight centimeters in the third year
- Between the age of three and puberty, about five to eight centimeters per year
- During puberty about seven to ten centimeters per year
The length of the legs is the most important factor in a person’s height. In the growth plate (epiphysis) of the long bones, the body continuously builds up new bone substance during the growth phase – the bone lengthens.
Via certain receptors in the liver, somatotropin leads to the release of IGF (insulin-like growth factors) – a hormone that causes the actual growth of various body tissues such as muscles or bones.
Expected final size
A person’s height is largely determined genetically. However, it also depends on external factors such as nutrition, possible illnesses and parental care. The expected final height of a person can be roughly calculated using a rule of thumb. The first step is to determine the average of the parents’ heights. For girls, 6.5 centimetres are subtracted from this value, whereas for boys, 6.5 centimetres are added.
Even more reliable is the measurement of bone maturity using an X-ray of the left hand. This allows relatively accurate conclusions to be drawn about the final or adult height.
What forms of short stature are there?
There are many forms of short stature. Depending on the point of view, these can be classified into different categories. For example, doctors differentiate between a primary and a secondary form of short stature. Primary short stature is when it occurs on its own. However, if it is only the direct or indirect consequence of another underlying disease, then it is a secondary form.
It is possible to make a further distinction, namely between proportionate and dysproportionate short stature: in proportionate short stature, all parts of the body are equally affected by the reduced growth, whereas in dysproportionate short stature, only individual parts are affected. In this case, for example, only the arms and legs are shortened, but the torso is of normal size, as is the case with achondroplasia.
How does short stature progress?
Short stature in itself is not necessarily associated with health risks. For example, if short stature occurs on its own and is not caused by a disease, there is no health impairment. Life expectancy is the same as for a person with normal height.
In certain forms of short stature, such as achondroplasia, there is increased strain on the joints. Although this often leads to premature signs of wear and tear, life expectancy is not reduced as a result.
However, if the cause of short stature is the rare hereditary disease osteogenesis imperfecta (brittle bone disease), this may lead to a reduced life expectancy. This depends on the type of osteogenesis imperfecta. The most common type of the disease is not associated with a shortened life expectancy.
What are the symptoms of short stature?
No general statements can be made about the symptoms of short stature, except of course that people with short stature have a reduced body length. Everything else depends on the type of short stature. However, doctors differentiate whether the symptoms that occur are actually the result of short stature or other signs of a common cause.
In some syndromic diseases, for example, short stature is only one of many possible symptoms. These diseases are all the result of a genetic defect. In achondroplasia, another genetic form of short stature, the short stature itself leads to further symptoms such as premature joint wear and tear and back pain.
What causes short stature?
There are countless causes that can lead to short stature. They can be divided into larger groups. The most important are briefly presented below:
Idiopathic short stature
Intrauterine dwarfism
If a child is born with short stature, the growth of the fetus was already delayed in the uterus. This is referred to as intrauterine dwarfism (uterus = womb). There are various causes for this, such as the mother being chronically ill during pregnancy, taking certain medication, smoking or drinking alcohol. Impaired function of the placenta can also lead to intrauterine dwarfism.
In most cases, the affected children make up for the growth deficit within the first two years of life.
Chromosomal disorders and syndromic diseases
In chromosomal disorders and syndromic diseases, short stature is caused by chromosomal abnormalities. DNA, the human genome, is organized into a total of 46 chromosomes. Certain disorders, in which there is an altered number of chromosomes or an error in the genetic material, lead in some cases to short stature, among other things.
Skeletal dysplasias
Skeletal dysplasias are characterized by impaired bone growth. The most common skeletal dysplasias are achondroplasia and its somewhat milder form, hypochondroplasia. Both are among the most common causes of short stature. In affected people, the longitudinal growth of the long bones is impaired. As a result, the extremities are shortened.
However, the bones are of normal thickness and the trunk is almost normal in length. In addition to short stature, a pronounced hollow back with flattened vertebrae and a disproportionately enlarged head with a bulging forehead are typical of achondroplasia.
Another skeletal dysplasia associated with short stature is osteogenesis imperfecta, better known as “brittle bone disease”. Due to impaired collagen synthesis, the bones of those affected are unstable and often break. A distinction is made between different types of osteogenesis imperfecta depending on the severity. While patients with the mildest variant still have an outwardly normal physique in some cases, the severe forms lead to deformities and short stature due to the numerous fractures.
Endocrine diseases
The thyroid hormones triiodothyronine (T3) and thyroxine (T4) are also important for healthy growth. For this reason, hypothyroidism, in which the thyroid gland produces too little of these hormones, is sometimes a cause of short stature.
Malnutrition (malnutrition)
Normal growth is not possible without an adequate and balanced diet. In countries where many people suffer from a lack of food, malnutrition is therefore a common cause of short stature.
If the food supply is sufficient, there are still diseases that can disrupt or prevent the absorption of nutrients from the intestine into the body. Typical causes of such malabsorption are chronic inflammatory bowel diseases (such as Crohn’s disease) and, above all, coeliac disease, which is based on an intolerance to gluten (gluten protein in cereals). Permanent malabsorption during the growth phase leads to short stature, as does malnutrition.
Organic and metabolic causes
In some cases, various disorders of the different organ systems and metabolic processes in the body lead to short stature. These include, in particular, diseases of the heart, lungs, liver, intestines and kidneys as well as disorders of carbohydrate, fat, protein and bone metabolism.
Constitutional delay in growth and puberty
Psychosocial causes
The effects of psychosocial circumstances on a child’s growth should not be underestimated. It is possible that psychological neglect can lead to short stature in a child, although the growth deficit can usually be made up if the environment changes in good time. The technical term for this type of neglect is “psychological deprivation”. Other psychological causes of short stature are eating disorders and depressive disorders.
How is short stature diagnosed?
Because there are so many possible causes of short stature, the approaches to diagnosis are also numerous and varied. First of all, the doctor measures the patient’s height to determine whether short stature is present at all. To do this, he compares the measured value with data from children of the same age.
If a child does in fact have short stature, an X-ray of the left hand can be used to determine the expected final height. This may reveal whether the short stature is already congenital or whether a normal final height is actually to be expected but growth is hindered by other diseases or deficiencies.
To get to the bottom of the cause, further diagnostics are carried out depending on the suspicion. This includes, for example
- Questioning the parents as to whether they experienced delayed pubertal development
- Search for other symptoms that are typical of chromosomal disorders or syndromic diseases. If there is a concrete suspicion, a targeted molecular genetic examination of the genetic material is carried out
- Examination and measurement of the skeleton for any disproportions
- Physical examination of the body and organ function, including a blood test to determine a deficiency or excess of relevant hormones, for example
- Metabolic diagnostics
- For children: Precise analysis of nutrition and determination of body weight and body mass index (BMI), for example to detect malnutrition
- For children: Assessment of the interaction between parents and child, assessment of the child’s psychosocial situation
These examinations are primarily carried out by the pediatrician or adolescent doctor as soon as short stature is suspected. In some cases, further clarification is carried out by a pediatric endocrinologist, a specialist in hormonal disorders in children.
How is short stature treated?
The treatment of short stature depends on its cause. If it is the result of another underlying condition, doctors will try to treat this. However, many forms of short stature cannot be treated at all or only inadequately.
Growth hormones
In some forms of short stature, it is advisable to administer artificial (“recombinant”) growth hormones, i.e. somatotropin or IGF, as required. This is the case, for example, if a deficiency of these growth hormones is the cause of short stature.
The administration of growth hormones is also advisable in many cases for other causes such as Ullrich-Turner syndrome, renal insufficiency or intrauterine dwarfism. This therapeutic approach may also have a positive effect in idiopathic dwarfism, although there are no clear studies to date.
Psychological support
Psychological support for people with dwarfism and their family environment may help them to cope better with the situation and its challenges.
Those affected can find help from the “Bundesverband Kleinwüchsige Menschen und ihre Familien e. V.”, or BKMF for short, at: https://www.bkmf.de
