annot be expected to respond to GH treatment.
People with Laron syndrome have strikingly low rates of cancer and diabetes.
Acromegaly is a syndrome that results when the anterior pituitary gland produces excess growth hormone (GH). A number of disorders may increase the pituitary’s GH output, although most commonly it involves a tumor called pituitary adenoma, derived from a distinct type of cell (somatotrophs). It leads to anatomical changes and metabolic dysfunction caused by elevated GH and insulin-like growth factor 1 (IGF-1) levels.
IGF-1 levels can be measured in the blood in 10-1000 ng/ml amounts. As levels do not fluctuate greatly throughout the day for an individual person, IGF-1 is used by physicians as a screening test for growth hormone deficiency and excess in acromegaly and gigantism.
Interpretation of IGF-1 levels is complicated by the wide normal ranges, and marked variations by age, sex, and pubertal stage. Clinically significant conditions and changes may be masked by the wide normal ranges. Sequential management over time is often useful for the management of several types of pituitary disease, undernutrition, and growth problems.
As a therapeutic agent
Patients with severe primary insulin-like growth factor-1 deficiency (IGFD), called Laron syndrome, may be treated with either IGF-1 alone or in combination with IGFBP-3. Mecasermin (brand name Increlex) is a synthetic analog of IGF-1 which is approved for the treatment of growth failure. IGF-1 has been manufactured recombinantly on a large scale using both yeast and E. coli.
Signaling through the insulin/IGF-1-like receptor pathway is a significant contributor to biological aging in many organisms. Cynthia Kenyon showed that mutations in the daf-2 gene double the lifespan of the roundworm, C. elegans. Daf-2 encodes the worm’s unified insulin/IGF-1-like receptor. Despite the impact of IGF1-like on C. elegans longevity, direct application to mammalian aging is not as clear as mammals lack dauer developmental stages. It is also inconsistent with evidence in humans.
There are mixed reports that IGF-1 signaling modulates the aging process in humans and about whether the direction of its effect is positive or negative.
Therapeutic administration of neurotrophic proteins (IGF-1) is associated with potential reversal of degeneration of spinal cord motor neuron axons in certain peripheral neuropathies.
The IGF signaling pathway is implicated in some cancers. People with Laron syndrome have a lessened risk of developing cancer. Dietary interventions and modifications such as vegan diets shown to downregulate IGF-1 activity, has been associated with lower risk of cancer. However, despite considerable research, perturbations specific to cancer are incompletely delineated and clinical drug trials have been unsuccessful.
IGF-1 has also been shown to be effective in animal models of stroke when combined with erythropoietin. Both behavioural and cellular improvements were found.
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