Definition

Tall stature is typically defined as height that significantly exceeds the average for a child's age and sex, as measured by WHO growth charts.

Causes

Genetics

Familial tall stature, also known as constitutional tall stature, is the most prevalent cause of above-average height. This condition often affects girls, whose mothers may recall having similarly tall statures during their childhood. Familial tall stature is typically a normal variation and not associated with any underlying health problems.

Hormonal and Chromosomal Disorders

Several hormonal and chromosomal disorders can also lead to tall stature, including:

• Hormonal disorders, such as:

  • Excessive growth hormone production: This condition causes gigantism in children and acromegaly in adults. Gigantism is characterized by rapid growth, especially in height, and involves large hands and feet, a prominent chin, a broad nose bridge, excessive sweating, high blood pressure, and issues with blood sugar regulation. The condition affects nearly all body parts, making them larger than average for the individual's age.

  • Hyperthyroidism: This is a condition where the thyroid gland becomes overactive, producing excess thyroid hormone. It is more common in women and is typically caused by Graves' disease, an autoimmune disorder.

  • Precocious puberty: In this condition, puberty begins unusually early—before age 8 in girls and before age 9 in boys. While a child with precocious puberty may initially have a tall stature, their adult height will often be shorter than average due to the premature closure of bone growth plates (epiphyses), influenced by estrogen.

• Chromosomal disorders, such as:

  • Trisomy X

  • Klinefelter syndrome: This is the most common chromosomal abnormality in males. Boys with Klinefelter syndrome typically experience late puberty, tall stature, smaller testicles, characteristic body shape, and sometimes breast growth. The diagnosis is often confirmed when these physical signs are accompanied by delayed bone age.

  • XYY syndrome.

  • Fragile X syndrome

• Metabolic syndromes and diseases, such as:

  • Marfan syndrome: This is caused by a mutation in the gene located on chromosome 15. 

  • Beckwith-Wiedemann syndrome: This is a condition of excessive fetal growth, often characterized by an abnormally large head, tongue, and abdominal organs, along with an enlarged liver and spleen, and low blood sugar levels.

  • Simpson-Golabi-Behmel syndrome

  • Sotos syndrome: Children with this syndrome exhibit excessive growth in both height and weight. 

  • Homocystinuria: A genetic metabolic disorder caused by a deficiency in the enzyme cystathionine synthase. The gene responsible for this condition is located on chromosome 21. Children with homocystinuria often have tall stature, long and slender fingers, mental retardation, and visual disturbances, such as lens dislocation.

Risk Factor

There are several factors that affect height, namely:

• Gender: Males tend to be taller than females.
• Health Status: Certain medical conditions can affect height.
• Nutrition: Overnutrition can lead to increased height.

Symptoms

Children with constitutional tall stature typically have no other symptoms. Hormonal causes may present with:

• Early puberty
• Abnormally large body parts
• Hyperactivity
• Hypertension

Diagnosis

Tall stature, in itself, is not considered a disease, but it can be indicative of underlying disorders. Several genetic conditions and syndromes that result in tall stature may also be associated with developmental delays, intellectual disabilities, and other complications. Therefore, it is crucial to identify the cause of tall stature in order to provide proper medical treatment and genetic counseling if needed.

The diagnostic process typically begins with a comprehensive physical examination followed by laboratory tests. Common tests to assess tall stature include:

• Karyotyping to detect genetic or syndromic disorders.
• T4 and TSH to check thyroid function.
• IGF-1 (Insulin-like Growth Factor-1).
• Bone age and final height prediction. An X-ray can be used to determine the child’s bone age. In some cases, conditions associated with tall stature may involve delayed or accelerated bone maturation.

In cases where a specific abnormality is suspected to be contributing to tall stature, additional diagnostic tests may be performed, including:

• LH (Luteinizing hormone), FSH (Follicle-stimulating hormone), and testosterone levels
• Glucose suppression test for growth hormone
• Visual field examination
• MRI of the brain to examine the pituitary gland that produce LH and FSH
• Blood cortisol
• Blood prolactin

Management

For children with constitutional tall stature, the primary approach is careful monitoring after evaluating bone age and predicting adult height. In cases where adult height is expected to be excessive and undesirable, treatment may be required to limit growth. This can include growth suppression therapy, which may involve hormonal treatments such as sex steroids. 

In girls, oral ethinylestradiol combined with cyclic progesterone has been shown to reduce adult height by about 7 cm. For boys, testosterone therapy at doses between 250-1000 mg per month has also demonstrated similar results. To achieve the best outcomes, these therapies should ideally be started early, before age 10 for girls and 12.5 for boys.

In some cases, surgical interventions may be recommended, such as epiphysiodesis, a procedure designed to slow down or stop the growth of the long bones, typically in the lower thigh and upper leg bones, to help reduce final adult height.

For tall stature related to nutritional issues, the treatment is focused on lifestyle modifications, including improving dietary habits and ensuring adequate nutrition. Hyperthyroidism, which can contribute to excessive growth, is treated with anti-thyroid medications.

In cases of excessive growth hormone production, octreotide (a somatostatin analog) can be administered at doses ranging from 37.5 to 50 mg once or twice a day via injection. This treatment can help reduce growth hormone secretion and has been shown to reduce final adult height by up to 5 cm.

Complications

Tall stature, while not typically associated with immediate physical health issues, can give rise to a number of complications, such as:

• Psychosocial complications. Tall individuals may experience difficulties in school and social settings. Parents may also be concerned about their children’s future relationships, especially in the case of girls. Furthermore, individuals with tall stature are at an increased risk of developing major depression.
• Cancer. Research suggests that taller individuals may have a higher incidence of certain types of cancer, but further studies are needed to understand this relationship fully.

Prevention

While constitutional tall stature and tall stature caused by genetic, hormonal, or syndromic disorders cannot be prevented, some cases of tall stature due to nutritional issues can be avoided. Implementing a healthy diet and making positive lifestyle changes can help prevent excessive growth related to poor nutrition and imbalanced eating habits.

When to See a Doctor?

Consult a doctor if your child is significantly taller than peers or shows signs of hormonal disorders for further evaluation.

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