Suspect when manifestations characteristic of gigantism are present. These include inappropriate excessive growth spurt, increased hand and foot size, dorsal kyphosis, manifestations of generalized osteoporosis, thickening of skin and soft tissue growth. If this is accompanied with CNS pressure manifestations it suggests a pituitary tumor.
Once suspected diagnostic investigations include glucose tolerance test and insulin-like growth factor-1 (IGF-1, somatomedin C) assays.
- Glucose tolerance test: Normally growth hormone is suppressed after oral intake of 50mg of glucose due to inhibition of GHRH secretion. In cases of gigantism growth hormone levels fail to suppress or may even rise.
- Insulin-like growth factor-1 (IGF-1, somatomedin C) assays are always elevated in gigantism and do not fluctuate like growth hormone levels.
Treatment is mainly surgical (transfenoidal adenectomy or hypophysectomy of the acidophil adenoma is the treatment of choice.
Bromocriptine paradoxically leads to a significant reduction in growth hormone levels. Cabergonline is another dopaminergic agent used to reduce growth hormone levels in gigantism.
Octreotide is a synthetic somatostatin analogue which is more effective than bromocryptine.
External radiotherapy is an option in treating acidophil adenomas.