Gigantism is a rare condition characterized by excessive growth and increased height in children and adolescents before their growth plates fuse. This accelerated growth occurs due to an overproduction of growth hormone (GH) in the body.
This hormonal imbalance typically stems from a non-cancerous tumor, an adenoma, in the pituitary gland at the base of the brain. The adenoma secretes excessive GH, leading to notable physical changes.
Unchecked GH levels affect height, organ size, and overall health. Early detection and timely intervention are important to mitigate long-term consequences and improve the outlook for affected individuals.
Primary Treatment Modalities
Treating gigantism involves reducing excessive growth hormone levels and managing the pituitary tumor. Treatment often incorporates surgery, medication, and sometimes radiation therapy, tailored to the patient’s specific needs to achieve optimal outcomes.
Surgical Intervention
Transsphenoidal surgery, also known as hypophysectomy, is often the initial treatment for gigantism. This procedure accesses the pituitary gland through the nasal cavity or an incision under the upper lip to remove the adenoma. The primary goal is to excise the tumor, normalizing growth hormone secretion and alleviating pressure on surrounding brain structures.
Success rates are higher for smaller tumors, where complete removal is more feasible. For many patients, successful surgery can normalize GH levels, halting or reversing excessive growth. Even when complete removal is not possible, surgery can debulk the tumor, making subsequent medical or radiation therapies more effective.
Medical Therapy
Pharmacological treatments are often used when surgery is not fully successful, when a patient is not a candidate for surgery, or as a primary intervention before an operation. Several medication classes control growth hormone secretion or block its action.
Somatostatin analogs
Somatostatin analogs, like octreotide and lanreotide, are common drugs for gigantism. They mimic natural somatostatin, inhibiting growth hormone release from the pituitary gland. These analogs reduce GH secretion, helping shrink the tumor and lower hormone levels.
Dopamine agonists
Dopamine agonists, such as cabergoline and bromocriptine, are another treatment option. These drugs activate dopamine receptors, which can suppress growth hormone production, especially in certain pituitary tumors. Though less effective than somatostatin analogs, they can be suitable for some patients, alone or combined with other therapies.
Growth hormone receptor antagonists
Growth hormone receptor antagonists, like pegvisomant, block growth hormone action at its receptor sites. This prevents GH from stimulating the liver to produce insulin-like growth factor 1 (IGF-1), a key mediator of growth. Pegvisomant is reserved for patients whose GH levels remain elevated despite other treatments.
Radiation Therapy
Radiation therapy is considered when surgical and medical treatments have not adequately controlled growth hormone levels or tumor growth. Its purpose is to destroy remaining tumor cells and gradually reduce growth hormone production.
Conventional radiation therapy delivers focused beams to the pituitary region over several weeks. Stereotactic radiosurgery, a more advanced form, delivers a highly concentrated dose in a single or few sessions. While effective, the full impact can take months to years to become apparent, as cellular damage and hormone reduction are gradual processes.
Aims of Treatment
Treatment for gigantism aims to restore hormonal balance and mitigate the effects of excessive growth hormone. A primary goal is to normalize growth hormone (GH) and insulin-like growth factor 1 (IGF-1) levels. Bringing these hormones into a healthy range helps halt abnormal growth and prevent complications.
Another objective involves shrinking or removing the pituitary tumor. Reducing tumor size relieves pressure on surrounding brain structures, such as the optic nerves, alleviating symptoms like headaches and visual disturbances.
Treatment also aims to alleviate symptoms from excess GH, including joint pain, excessive sweating, and changes in facial features. Addressing these symptoms enhances comfort and quality of life. The aim is also to prevent or reverse long-term health complications like cardiovascular disease, diabetes, and arthritis. Successful treatment improves overall well-being and promotes a healthier life.
Long-Term Monitoring and Management
Following initial gigantism treatment, ongoing care ensures sustained remission and manages lingering health issues. Regular medical follow-up assesses the patient’s hormonal status and overall health, helping detect recurrence or new complications.
Follow-up visits involve periodic blood tests to monitor growth hormone (GH) and insulin-like growth factor 1 (IGF-1) levels. MRI scans of the brain are also performed regularly to assess the pituitary gland for residual tumor tissue or regrowth. These diagnostic tools provide information for adjusting treatment plans.
Many individuals may experience residual health issues even after successful primary treatment. Conditions like diabetes, hypertension, and joint problems, developed due to prolonged GH excess, require continued management. Specialized care for these complications helps maintain health and prevent deterioration.
Some patients may require hormone replacement therapy if pituitary function is impaired by the tumor or treatment. This can include replacement of thyroid hormones, cortisol, or sex hormones, also produced by the pituitary gland. Ensuring proper hormone balance supports overall bodily function. Patient education and support are components of long-term care, empowering individuals to understand their condition, adhere to treatment plans, and connect with support networks.