Gigantism

What is Gigantism?

Gigantism is a rare condition that causes abnormal and excessive growth in children and adolescents. It happens when the body produces too much growth hormone before the growth plates in the bones close. This leads to height significantly above average for age and sex.

The condition typically results from a pituitary adenoma, a noncancerous tumor in the pituitary gland at the base of the brain. The pituitary gland controls many hormones in your body, including growth hormone. When a tumor develops, it can cause the gland to release far more growth hormone than normal. This excess hormone triggers the liver to produce too much insulin-like growth factor 1, or IGF-1, which drives bone and tissue growth.

Gigantism only occurs when excess growth hormone happens before puberty ends and growth plates close. Once growth plates fuse in adulthood, the same condition causes acromegaly instead, which leads to enlarged hands, feet, and facial features rather than increased height. Early detection and treatment can help manage symptoms and prevent complications.

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Symptoms

Abnormally rapid growth and height well above the 97th percentile for age
Very large hands and feet for age
Thickening of facial features, including prominent forehead and jaw
Widely spaced teeth due to jaw enlargement
Delayed puberty or irregular periods
Excessive sweating and body odor
Joint pain and limited mobility
Headaches and vision problems
Fatigue and weakness
Deep or hoarse voice

Some children may not notice symptoms early on beyond rapid growth. Parents often bring children to the doctor when height becomes noticeably excessive compared to peers. Vision changes or headaches may indicate the tumor is pressing on nearby brain structures.

Causes and risk factors

Gigantism is almost always caused by a pituitary adenoma, a benign tumor in the pituitary gland. This tumor produces excess growth hormone without the normal feedback controls that regulate hormone levels. The excess growth hormone then signals the liver to produce high levels of IGF-1, which drives bone growth. In very rare cases, tumors in other parts of the body or genetic conditions can cause excess growth hormone production.

Risk factors are not well understood because the condition is so rare. Most pituitary adenomas develop without a clear cause. Some genetic syndromes, such as Multiple Endocrine Neoplasia type 1 or McCune-Albright syndrome, increase the risk of pituitary tumors. Family history of pituitary tumors may also slightly increase risk. The condition affects boys and girls equally and typically appears during the rapid growth phase of childhood or adolescence.

How it's diagnosed

Doctors diagnose gigantism through a combination of physical examination, growth chart analysis, and blood tests. They measure growth hormone and IGF-1 levels to confirm excess production. Because growth hormone levels fluctuate throughout the day, a single measurement may not be enough. Doctors often use a glucose suppression test, where you drink a sugar solution and growth hormone is measured over several hours. In healthy individuals, glucose lowers growth hormone levels, but in gigantism, levels remain high.

IGF-1 testing is particularly useful because levels remain stable throughout the day and directly reflect growth hormone activity. Elevated IGF-1 in children and adolescents with open growth plates strongly indicates excess growth hormone secretion. Rite Aid offers add-on testing for both Growth Hormone and IGF-1 to help detect and monitor this condition. After blood tests confirm the diagnosis, doctors typically order an MRI of the brain to locate and measure the pituitary tumor.

Treatment options

Surgical removal of the pituitary tumor, which is the primary treatment for most cases
Medications such as somatostatin analogs to block growth hormone release
Growth hormone receptor blockers like pegvisomant to prevent hormone effects
Radiation therapy if surgery does not fully remove the tumor or if it returns
Regular monitoring of growth hormone and IGF-1 levels after treatment
Physical therapy to address joint pain and mobility issues
Vision and endocrine testing to monitor for complications
Nutritional support to maintain healthy weight and bone strength

Frequently asked questions

Gigantism occurs when excess growth hormone happens before puberty, when growth plates are still open. This causes excessive height. Acromegaly occurs when excess growth hormone happens in adulthood after growth plates have closed. Instead of height increase, acromegaly causes enlarged hands, feet, and facial features.

Height varies widely depending on when the condition starts and how long it goes untreated. Many individuals with gigantism reach heights of 7 feet or more. Early diagnosis and treatment can prevent extreme height and reduce complications. Without treatment, growth continues until the growth plates naturally close.

Gigantism can often be successfully treated, especially when caught early. Surgical removal of the pituitary tumor cures many cases. If surgery is not fully successful, medications can control growth hormone levels. Regular monitoring ensures hormone levels stay in the healthy range after treatment.

Doctors use Growth Hormone and IGF-1 blood tests to detect gigantism. IGF-1 is particularly useful because levels stay stable throughout the day and directly reflect growth hormone activity. Elevated IGF-1 in children with rapid growth strongly suggests excess growth hormone production. A glucose suppression test may also be used to confirm the diagnosis.

Most cases of gigantism occur randomly without a family history. However, some genetic syndromes increase the risk of pituitary tumors, including Multiple Endocrine Neoplasia type 1 and McCune-Albright syndrome. If you have a family history of pituitary tumors or these syndromes, talk to your doctor about monitoring.

Untreated gigantism can lead to serious health problems. These include heart disease, high blood pressure, diabetes, arthritis, and nerve compression. Vision problems can occur if the tumor presses on the optic nerves. Early treatment helps prevent or reduce these complications and improves long-term health outcomes.

If surgery does not fully remove the tumor or cure the condition, medications can control growth hormone levels. Somatostatin analogs like octreotide block growth hormone release. Growth hormone receptor blockers like pegvisomant prevent the hormone from affecting tissues. Radiation therapy may be used if the tumor grows back or cannot be fully removed.

After treatment, regular monitoring is essential to ensure growth hormone and IGF-1 levels stay normal. Most doctors recommend testing every 3 to 6 months initially, then less frequently once levels stabilize. Lifelong monitoring may be needed because tumors can return. Your doctor will create a personalized testing schedule based on your treatment and response.

Lifestyle changes cannot cure gigantism or lower growth hormone levels. However, healthy habits support overall well-being during and after treatment. Regular physical activity helps maintain joint health and muscle strength. A balanced diet supports bone health and helps prevent diabetes and heart disease, which are more common in people with gigantism.

See a doctor if your child is growing much faster than peers or is significantly taller than expected for their age. Other warning signs include severe headaches, vision changes, or delayed puberty alongside rapid growth. Early diagnosis and treatment lead to better outcomes and can prevent serious complications.