Gigantism is characterized by abnormal growth in children due to excessive production of insulinlike growth factor I (IGF-I). Basically there is excess production of growth hormone which contributes to the accelerated linear growth.
Presentation
Children with gigantism are taller than other age matched children. In many instances, certain parts are proportionately bigger than other parts. Affected children can also have long hands and feet, with signs of thickening of fingers and toes along with a prominent forehead and jaw. Children with gigantism may also have coarse facial features which include a larger than normal head, flat nose, and large lips and tongue.
Symptoms of gigantism largely depend on the size of the tumor on the pituitary gland. When the tumor gradually increases in size, it may exert pressure on the neighboring nerves in the brain. This may further cause the children to suffer from headaches or loss of vision. In addition, children would also experience weakness, fertility problems, delay in onset of puberty and excessive sweating. In severe cases, deafness can also set in [7].
Workup
Measuring the blood levels of growth hormone and insulinlike growth factors forms the preliminary basis of diagnostic procedure. Another method of measuring the insulinlike growth factor is to determine the levels about 1 hour after administration of a glucose load. Under normal circumstances, the hormone levels decrease after a glucose load. In children with gigantism, the values remain normal even after consuming glucose. This indicates that the body produces excessive growth hormones, which causes the levels to remain normal [8]. Imaging studies such as CT scan and MRI are indicated to detect the location as well as size of the tumor in the pituitary gland.
Treatment
Treatment of gigantism is aimed at slowing down the progression of production of growth hormones as well as effective management of symptoms. The following methods are employed in order to fulfill the objectives:
- Surgery is the first line of treatment if tumors in the pituitary gland are the major factor for gigantism.
- Medicines are employed when surgery cannot be performed. In such cases, medications are administered for management of the symptoms. Medicines such as lanreotide or octreotide are given monthly intravenously to reduce the excessive production of growth hormones. Another new drug known as pegvisomant has been developed to lower the production of growth hormones. The drug has to be injected daily and is used when other options or medications fail to yield positive results [9].
- Gamma knife radiosurgery: This type of method is given when surgery is not an option. In such cases, high beam radiation is given to the tumor cells in order to destroy it. This method takes several years for bringing the levels of growth hormone back to normal and is also associated with several side effects; hence it is used very rarely [10].
Prognosis
Research has shown that, about 80% of cases can be successfully treated with surgery to remove the tumor. In situations, when surgery cannot be successfully accomplished then medications are employed for effective management of symptoms. In either of the cases, individuals can live a long and healthy life [6].
Etiology
Development of a tumor in the pituitary gland is the major cause of gigantism. Excessive release of growth hormone due to a benign tumor in the pituitary gland favors abnormal growth development in children [2].
In addition to excess production of growth hormones, gigantisms can also occur as a result of other conditions, which include neurofibromatosis, Carney complex, multiple endocrine neoplasia type I, tuberous sclerosis and McCune-Albright syndrome. It has been estimated that, about 20% patients suffering from gigantisms also suffer from McCune-Albright syndrome [1].
Epidemiology
Gigantism is a rare phenomenon, and only about 100 cases are reported till date. The condition of acromegaly is more common than gigantism, with a reported incidence of 3 – 4 cases per million each year; having a prevalence rate of 40 – 70 cases per million population. Gigantism can strike at any age before the epiphyseal fusion takes place. Agromegaly occurs in the third decade of life; with mean age of diagnosis being 40 years and 54 years in females and males respectively [4]. No sex predilection is known.
Pathophysiology
The excess production of insulinlike growth factor can be divided into the following factors:
- Production and release of excessive growth hormone from the pituitary gland
- Increase in the secretion of growth hormone releasing hormone
- Excess production of insulinlike growth hormone-binding protein, which in turn is responsible for prolonging the half-life of insulinlike growth hormone
- The malfunctioning of the pituitary gland due to development of benign tumor is the major cause, and this promotes excessive production of growth hormones. This gland is located at base of the brain and is important for production of hormones that control the various functions of the body [5].
Prevention
Gigantism cannot be prevented. However, with early initiation of treatment, the onset of complications can certainly be kept at bay.
Summary
Gigantism occurs during childhood, much before the epiphyseal growth plates have closed. Early diagnosis along with prompt initiation of treatment is important for arresting the accelerated growth pattern. However, many parents fail to recognize that their child is suffering from gigantism as they consider the sudden growth as normal childhood growth spurts. Individuals with gigantism measure between 2.13 m to 2.74 m [1].
Patient Information
- Definition: Gigantism is a condition wherein there is excessive production of growth hormones that causes abnormal growth in affected children. Prompt diagnosis and early initiation of treatment is required to arrest complications to set in.
- Cause: Excessive production of growth hormones due to development of tumor in the pituitary gland is the major cause for gigantism. Other less common causes include various conditions such as neurofibromatosis, Carney complex, multiple endocrine neoplasia type I and McCune-Albright syndrome.
- Symptoms: Symptoms of gigantism include larger than normal height compared to other children of same age. Affected children also suffer from delayed onset of puberty, difficulty in vision, sleep problems, weakness, excessive sweating, prominent jaws, headache, irregular menstruation, larger than normal hands and feet which have thickened fingers and toes.
- Diagnosis: Determining the blood levels of growth hormone helps in arriving at a definitive diagnosis. The levels of the hormone can also be checked an hour later after administration of glucose load. MRI and CT scan would be required for locating the site and determining the shape of the tumor.
- Treatment: Surgery forms the first line of treatment. If surgery isn’t an option then, medications are given to control the excessive production of growth hormones. A new drug that has been introduced to control the growth hormone release is pegvisomant. Gamma knife radiosurgery is the last resort and employed only when surgery and medications have not been successful in bringing about the desired results.
References
- Tanner JM, Davies PS. Clinical longitudinal standards for height and height velocity for North American children. J Pediatr 1985; 107:317.
- Nainggolan L. Gene Discovery in Giants Could Shed Light on Human Growth. Medscape Medical News.
- Sotos JF. Overgrowth.Hormonal Causes.ClinPediatr (Phila) 1996; 35:579.
- Giustina A, Chanson P, Bronstein MD, Klibanski A, Lamberts S, Casanueva FF, et al. A consensus on criteria for cure of acromegaly. J ClinEndocrinolMetab. Jul 2010;95(7):3141-8.
- Khandelwal D, Khadgawat R, Mukund A, Suri A. Acromegaly with no pituitary adenoma and no evidence of ectopic source. Indian J EndocrinolMetab. Sep 2011;15Suppl 3:S250-2.
- Thomsett MJ. Referrals for tall stature in children: a 25-year personal experience. J Paediatr Child Health 2009; 45:58.
- Abe T, Tara LA, Lüdecke DK. Growth hormone-secreting pituitary adenomas in childhood and adolescence: features and results of transnasal surgery. Neurosurgery. Jul 1999;45(1):1-10
- Sippell WG, Partsch CJ, Wiedemann HR. Growth, bone maturation and pubertal development in children with the EMG-syndrome. Clin Genet 1989; 35:20.
- Rix M, Laurberg P, Hoejberg AS, Brock-Jacobsen B. Pegvisomant therapy in pituitary gigantism: successful treatment in a 12-year-old girl. Eur J Endocrinol. Aug 2005;153(2):195-201
- Jagannathan J, Yen CP, Pouratian N, Laws ER, Sheehan JP. Stereotactic radiosurgery for pituitary adenomas: a comprehensive review of indications, techniques and long-term results using the Gamma Knife. J Neurooncol. May 2009;92(3):345-56.