Serum IGF-1 in treated acromegaly - how normal is "normal"?

Area of Science:

• Endocrinology
• Neuroendocrinology
• Metabolic Disorders

Background:

• Acromegaly, a disorder caused by excess growth hormone (GH), is typically managed with surgery to remove pituitary tumors.
• Post-surgical management often relies on normalizing serum Insulin-like Growth Factor-1 (IGF-1) levels, a key indicator of GH activity.

Observation:

• Four acromegalic patients presented with persistent symptoms (sweating, joint pain, reduced hand suppleness) despite achieving normal serum IGF-1 levels post-surgery.
• Three patients experienced symptom improvement with pegvisomant treatment, which lowered IGF-1 levels within the normal range.
• One patient exhibited persistent night sweats despite fluctuating normal IGF-1 levels; two patients failed to suppress GH during oral glucose tolerance tests.

Findings:

• Normal serum IGF-1 levels may not always correlate with complete symptom resolution in treated acromegaly.
• Individualized IGF-1 targets, potentially in the lower half or lowest quartile of the normal range, may be necessary for optimal symptom control.
• Inadequate GH suppression during oral glucose tolerance tests in some patients with normal IGF-1 highlights the complexity of acromegaly management.

Implications:

• Clinicians should critically assess IGF-1 levels in treated acromegaly patients, considering symptom relief as a primary endpoint alongside population norms.
• Pegvisomant may be a valuable therapeutic option for achieving symptom control in acromegaly patients with persistent symptoms despite normal IGF-1.
• Further research is warranted to establish personalized IGF-1 targets and refine diagnostic criteria for optimal acromegaly management.