Gigantism

• Gigantism is a rare condition caused by excessive growth hormone (GH) production before puberty.
• It primarily results from a benign pituitary tumor, leading to abnormally rapid growth and other physical changes.
• Diagnosis involves blood tests for GH and IGF-1 levels, along with pituitary MRI scans.
• Effective treatment typically includes surgery to remove the tumor, often supplemented by medication or radiation.
• Untreated gigantism can lead to severe long-term health complications, including cardiovascular issues and diabetes.

What is Gigantism?

Gigantism refers to a rare medical condition characterized by excessive growth and height, significantly above average for a person’s age and sex. This disorder typically manifests in childhood or adolescence, before the epiphyseal growth plates in the long bones have closed. The primary underlying cause is the overproduction of growth hormone (GH) by the pituitary gland, a small gland located at the base of the brain.

This abnormal secretion of GH leads to an accelerated growth rate, causing children to grow much taller than their peers. While rare, affecting approximately 3 in a million people, according to the National Organization for Rare Disorders (NORD), early recognition and intervention are crucial to manage the condition and prevent severe health complications in adulthood.

Causes, Symptoms, and Diagnosis of Gigantism

The primary factor that causes gigantism in children is almost always a benign tumor, known as an adenoma, located in the pituitary gland. This tumor leads to an uncontrolled and excessive secretion of growth hormone (GH). In very rare instances, genetic conditions such as Multiple Endocrine Neoplasia type 1 (MEN1), McCune-Albright syndrome, or Carney complex can predispose individuals to developing pituitary tumors and, consequently, gigantism.

The symptoms and diagnosis of gigantism are typically identified through a combination of physical examination, laboratory tests, and imaging studies. Key indicators include:

• Abnormally rapid increase in height and overall body size.
• Enlarged hands and feet, often requiring frequent changes in shoe and glove sizes.
• Coarse facial features, including a prominent jaw (prognathism) and forehead.
• Headaches and vision problems, particularly if the pituitary tumor presses on nearby optic nerves.
• Excessive sweating, joint pain, and muscle weakness.
• Delayed puberty or irregular menstrual cycles in girls.

Diagnosis is confirmed through blood tests that measure elevated levels of growth hormone and insulin-like growth factor 1 (IGF-1). An oral glucose tolerance test (OGTT) is often used, as glucose typically suppresses GH release; in individuals with gigantism, GH levels remain high. Magnetic resonance imaging (MRI) of the pituitary gland is essential to locate and assess the size of any existing tumor.

Effective Treatment and Long-Term Effects of Gigantism

The goal of how gigantism is treated effectively is to normalize growth hormone levels, reduce tumor size, and alleviate symptoms. The primary treatment approach is typically surgical removal of the pituitary tumor, a procedure often performed through the nose (transsphenoidal surgery). This surgery is highly effective in many cases, especially when the tumor is small and well-defined.

If surgery is not fully successful in normalizing GH levels or if the tumor cannot be completely removed, medical therapy may be initiated. Medications such as somatostatin analogs (e.g., octreotide, lanreotide) can reduce GH secretion, while dopamine agonists (e.g., cabergoline) may be effective for certain types of tumors. Growth hormone receptor antagonists (e.g., pegvisomant) block the action of GH on target tissues. Radiation therapy, including stereotactic radiosurgery, is another option for residual tumors or when other treatments have failed, though its effects are slower and can have long-term side effects.

The effects of gigantism on the human body, if left untreated, can be severe and life-threatening. Chronic exposure to high levels of GH can lead to significant health complications, including cardiovascular diseases such as hypertension, cardiomyopathy (enlarged heart), and an increased risk of heart failure. Other potential long-term issues include type 2 diabetes mellitus, arthritis, sleep apnea, carpal tunnel syndrome, and an elevated risk of certain cancers. Early diagnosis and comprehensive, multidisciplinary treatment are crucial to prevent these complications, improve quality of life, and ensure a near-normal life expectancy for affected individuals.