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Acromegaly with normal basal growth hormone levels
G Mohr1, Z P Chen, M Schweitzer
1Division of Neurosurgery, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montréal, Québec, Canada.
Summary
Acromegaly can occur without elevated growth hormone (GH) levels, often due to high insulin-like growth factor 1 (IGF-1). Pituitary tumors may transform, leading to atypical presentations of this GH excess disorder.
Area of Science:
- Endocrinology
- Oncology
Background:
- Acromegaly is typically caused by excessive growth hormone (GH) secretion.
- This case highlights an unusual presentation of acromegaly.
Observation:
- A 42-year-old male presented with acromegalic features over 5 years.
- Imaging revealed a large pituitary mass extending into the sphenoid sinus.
- The patient had normal basal GH but elevated insulin-like growth factor 1 (IGF-1).
Findings:
- The pituitary adenoma was confirmed as mammo-somatotrophic but immunocytochemistry showed only prolactin (PRL) positivity.
- Despite normal GH, elevated IGF-1 and impaired GH regulation were noted.
- Surgical removal of the pituitary adenoma was performed via transsphenoidal microsurgery.
Implications:
- Elevated IGF-1 can cause acromegaly even with normal GH levels.
- Pituitary tumors may undergo morphological transformation, affecting hormone secretion.
- Other potential causes include hyperinsulinemia or growth hormone receptor antibodies.