From the Guidelines
IGF-1 increases in acromegaly due to excessive growth hormone (GH) secretion, typically from a pituitary adenoma, as supported by the most recent evidence from 1.
Pathophysiology of Acromegaly
Growth hormone stimulates the liver to produce insulin-like growth factor 1 (IGF-1), which mediates many of GH's growth-promoting effects. In acromegaly, the pituitary tumor continuously secretes GH, bypassing normal regulatory feedback mechanisms that would typically suppress GH release. This persistent GH elevation leads to sustained overproduction of IGF-1 by the liver.
Clinical Manifestations and Diagnosis
The elevated IGF-1 levels are responsible for many clinical manifestations of acromegaly, including soft tissue overgrowth, organomegaly, and metabolic disturbances. IGF-1 measurement is actually preferred over GH for diagnosing and monitoring acromegaly because it remains relatively stable throughout the day, unlike GH which fluctuates, making IGF-1 a more reliable biomarker of disease activity, as noted in 1.
Treatment Approaches
Treatment approaches for acromegaly, including surgery, medication (somatostatin analogs like octreotide, GH receptor antagonists like pegvisomant), and radiation therapy, aim to normalize both GH and IGF-1 levels to alleviate symptoms and reduce complications. The goal is to improve morbidity, mortality, and quality of life for patients with acromegaly, as emphasized by the need for tailored management strategies discussed in 1 and the importance of monitoring and adjusting treatment based on IGF-1 levels and clinical response.
From the Research
Causes of IGF-1 Increase in Acromegaly
- IGF-1 increase in acromegaly is primarily due to the excess secretion of growth hormone (GH) by a pituitary adenoma 2, 3, 4, 5.
- The excess GH leads to an increase in the production of insulin-like growth factor 1 (IGF-1), resulting in the clinical manifestations and comorbidities associated with acromegaly 2, 6, 3, 4, 5.
Relationship Between GH and IGF-1
- GH and IGF-1 levels should be considered in concert when diagnosing and treating acromegaly 2.
- Elevated serum IGF-1 concentrations are a key diagnostic criterion for acromegaly, and GH levels may be <1.0 µg/L after oral glucose suppression in early or mild cases 2.
- The increase in IGF-1 levels is a direct result of the excess GH secretion, and reducing GH levels is essential to decrease IGF-1 levels and manage the disease 6, 3, 4, 5.
Clinical Implications
- The increase in IGF-1 levels in acromegaly can lead to various systemic complications, including cardiovascular, cerebrovascular, and pulmonary dysfunction, which can result in a decreased quality of life and life expectancy 3, 4, 5.
- Early diagnosis and treatment of acromegaly are crucial to mitigate these complications and improve patient outcomes 2, 3, 4, 5.