What Is Gigantism

Overview

Gigantism is an extremely rare endocrine disorder characterized by uncontrolled growth beyond average height, resulting from the excessive production of growth hormone due to growth hormone hypersecretion.^1,2,3 

This article provides a comprehensive overview of gigantism, delving into its causes, early symptoms, diagnosis, risk factors, complications, and management options. Additionally, it highlights the distinction between gigantism and acromegaly, another condition linked to excess growth hormone production. 

By understanding the intricacies of gigantism and its management, individuals and healthcare professionals can better navigate this uncommon hormonal disorder and work towards optimal care and improved quality of life. 

Difference between gigantism and acromegaly

Acromegaly and gigantism are two related hormonal conditions that differ in their onset and timing. 

Acromegaly is a hormonal disorder that occurs when the pituitary gland in the base of the brain produces excessive growth hormone after the person's growth plates have closed. The main cause of acromegaly is a non-cancerous tumor called pituitary adenoma, which presses on the gland. 

Gigantism develops before the growth plates of large bones have closed, while acromegaly typically occurs in adulthood after the growth plates have closed. Due to this adult onset, acromegaly does not lead to an increase in height but instead only leads to bone and tissue enlargement. Both conditions are often caused by pituitary adenomas.

Causes of gigantism

The primary cause of gigantism is the excessive production of growth hormone, often resulting from benign tumors on the pituitary gland. In rare situations, genetic mutations  or non-pituitary tumors can also lead to gigantism.³ Gigantism is associated with certain conditions which increases the risk of development like: 

• Neurofibromatosis
• Carney complex
• McCune-Albright syndrome

 Furthermore, other pituitary disorders, such as acromegaly, which involves excessive growth hormone production in adulthood, can also elevate the risk of gigantism.

Signs and symptoms of gigantism

The indications of gigantism are characterized by various physical and physiological changes. The most prominent features are:  

• An abnormal increase in height and overall growth, often accompanied by enlargement of the hands and feet due to soft tissue swelling and bony expansion This can result in a doughy swollen consistency of the flesh¹ 
• Coarse facial features  including an enlarged nose, lips, and a protruding jaw, as well as widely spaced teeth
• Approximately 60% of gigantism patients experience carpal tunnel syndrome due to swelling of the median nerve 

Additional manifestations may include: 

• Enlarged tongue
• Overbite
• Acne
• Broad nose
• A prominent supraorbital bridge
• Prognathism (a protruding jaw) which can lead to malocclusion of the teeth¹ 

In addition to these physical signs, individuals may experience: 

• General weakness
• Lethargy 
• Excessive sweating
• Skin tags  which result from the excessive production of epithelial cells associated with the condition¹
• Vision problems due to pressure exerted  on the nerves 
• Impaired or delayed puberty may also be observed in affected individuals

Management and treatment for gigantism

The primary goal of treatment for gigantism is to control the production of growth hormone, prevent further growth, and manage symptoms. 

The preferred initial treatment option is surgical removal of the tumor, followed by the measurement of growth hormone and IGF-1 levels 12 weeks after surgery. This approach aims to reduce or eliminate the pituitary tumor, normalize IGF-1 levels, alleviate symptoms, and monitor the condition and associated comorbidities. 

Various medical therapies are available for the management of gigantism. 

• Dopamine agonists can be used to decrease growth hormone secretion, by increasing dopamine secretion  
• Somatostatin receptor ligands mimic somatostatin and inhibit growth hormone secretion. 
• Medications such as somatostatin analogs may also be prescribed 

In cases where the pituitary tumor cannot be removed surgically, alternative surgical options may be considered. 

Radiation therapy is another treatment modality that can be employed to reduce tumor size and regulate growth hormone levels.¹  Radiation therapy, particularly external irradiation targeted at the pituitary fossa, has been shown to achieve normal IGF-1 levels in approximately 60% of patients within 10 years of treatment. Additionally, stereotactic single high-dose irradiation involves delivering a concentrated dose of radiation to a specific area. 

Overall, treatment approaches for gigantism involve a combination of surgical, medical, and radiation therapies aimed at controlling hormone levels, reducing tumor size, and managing symptoms. The choice of treatment depends on the individual case and should be determined in consultation with healthcare professionals.

Diagnosis of gigantism

A comprehensive diagnosis of gigantism requires a physical examination and a thorough review of the patient's medical history. The initial step in the diagnostic process involves measuring the levels of insulin-like growth factor 1 (IGF-1). Normal levels of IGF-1 effectively rule out the presence of acromegaly. However, if the levels are elevated, further testing is required to confirm the diagnosis of acromegaly or gigantism. An oral glucose tolerance test with growth hormone measurement is typically conducted to establish a definitive diagnosis. 

Additionally, magnetic resonance imaging (MRI) is used to assess the location, size, and potential compression of the optic chiasm and invasion of the cavernous sinus.¹ Hormone level blood tests are employed to measure the levels of growth hormone in the blood. Imaging techniques such as MRI and CT scans are utilized to detect the presence of pituitary tumors and evaluate their severity. 

In some cases, genetic testing may be performed to identify underlying genetic mutations that contribute to the condition. By employing these diagnostic tools and techniques, healthcare professionals can accurately diagnose gigantism and develop an appropriate treatment plan.

Risk factors

There are multiple risk factors for gigantism, with the most common cause of the condition being a pituitary adenoma, which can lead to excessive growth hormone production. Various risk factors play a role in the likelihood of developing the condition including: 

• Certain medical conditions 
• Genetic predispositions- genetic mutations can also increase the chances of developing gigantism and pituitary adenomas
• Gender- people assigned male at birth men are more susceptible to gigantism compared to people assigned female at birth
• Age- The age of onset is particularly important, as excessive growth hormone can have a significant impact on children whose bodies are still growing
• Family history- Individuals with a family history of gigantism, especially if it involves genetic mutations, are at a higher risk

Recognizing these risk factors is crucial in assessing the likelihood of gigantism and identifying individuals who may be at a higher risk of developing the condition. It is important to note that gigantism is a very rare condition, and the majority of people with pituitary adenomas will not develop gigantism.

Complications

The prognosis of gigantism depends on the timing of diagnosis and the response of hormone levels to treatment, whether surgical or non-surgical. Individuals with acromegaly are prone to cardiovascular issues, with approximately 40% of patients experiencing hypertension. To detect potential cardiomyopathy,  regular monitoring through yearly ECG and echocardiograms is recommended. If left untreated, gigantism can lead to a range of complications. The increased strain on the heart and blood vessels can result in cardiovascular problems. Moreover, the high levels of growth hormone in the body can contribute to insulin resistance and the development of diabetes.

Joints may experience significant strain, leading to mobility issues, pain, and arthritis. Early onset osteoarthritis may occur, particularly in the knees, hips, and spine, due to incongruent articular joint surfaces.¹ 

Obstructive sleep apnea, characterized by upper airway tissue swelling and an enlarged tongue, is present in approximately 70% of acromegaly patients. 

Arthropathy, caused by nerve entrapment from soft tissue swelling and bony expansion, affects around 75% of patients.² Additionally, vision loss may be a complication to be mindful of. 

To mitigate these complications, early diagnosis and appropriate treatment are crucial in managing gigantism and minimizing its impact on overall health and well-being. Regular follow-up and monitoring are essential to address potential complications and optimize the long-term prognosis for individuals with gigantism.

FAQs

Can gigantism be prevented?

Preventing gigantism involves early diagnosis and intervention, typically through surgical removal of the tumor or abnormal tissue causing excess growth hormone production. 

Regular medical monitoring and lifestyle modifications, such as a balanced diet and exercise, are important for managing the condition and associated health issues. 

Genetic counseling can provide guidance for individuals with a genetic predisposition to gigantism, aiding in informed family planning decisions.

How common is gigantism?

Gigantism is a rare condition, affecting approximately 2 to 3 cases per million people. It is considered an uncommon hormonal disorder.

What is the difference between gigantism and acromegaly?

Gigantism and acromegaly are both conditions caused by excessive production of growth hormone, but they differ in the timing of onset. 

Gigantism occurs when excess growth hormone is produced before the closure of growth plates during childhood and adolescence, resulting in excessive height and overall body enlargement. 

Acromegaly, on the other hand, occurs when excess growth hormone is produced after the closure of growth plates, leading to gradual enlargement of certain body parts, such as the hands, feet, and facial features, in adults.

When should I see a doctor?

If you suspect acromegaly or gigantism, seek medical attention promptly. Look out for symptoms like abnormal growth patterns, enlarged body parts, joint pain, and vision changes. Consult an endocrinologist for diagnosis and treatment.

Summary

In conclusion, gigantism is a rare endocrine disorder characterized by excessive growth due to the overproduction of growth hormone. Early diagnosis, effective management, and prompt treatment are crucial in mitigating the complications associated with gigantism. By understanding the causes, recognizing the symptoms, and seeking medical attention, individuals with gigantism can receive appropriate care and support. Ongoing monitoring, lifestyle modifications, and various treatment options can help control growth hormone production, manage symptoms, and improve overall well-being. 

Further research and advancements in medical interventions continue to enhance the understanding and treatment of gigantism, offering hope for those affected by this unique condition.