Acromegaly
Acromegaly is characterized by GH and IGF-1 hypersecretion and GH and IGF-1 play important roles in regulating body composition and glucose homeostasis.
History
Pierre Marie coined the term 'acromegaly' in 1886 and linked this to a distinct clinical disease with a characteristic clinical picture. However, Pierre Marie was not the first physician to give a full record of the clinical picture of acromegaly, but others had preceded him, like the Dutch physician Johannes Wier.
After Marie, pituitary enlargement was noted in almost all patients with acromegaly. Subsequently it was discovered that pituitary hyperfunction caused by a pituitary tumour was indeed the cause of acromegaly.
Epidemiology
An increased rate of acromegaly was reported in industrialized areas, suggesting an involvement of environmental pollutants in the pathogenesis and behavior of GH secreting pituitary neuroendocrine tumors 1).
Classification
Acromegaly Classification can be approached in different ways depending on the clinical, biochemical, etiological, and radiological aspects. Here’s a structured summary:
🔹 1. Etiological Classification Pituitary Adenoma (≈98%)
Somatotroph adenoma (GH-secreting)
Mixed GH/Prolactin adenoma
Ectopic GH or GHRH Secretion (<2%)
From tumors like bronchial carcinoids, pancreatic neuroendocrine tumors
🔹 2. Biochemical Classification Based on GH and IGF-1 levels:
Active Acromegaly:
Elevated IGF-1 (age-adjusted)
Inadequate suppression of GH after oral glucose tolerance test (OGTT)
Controlled/Remission:
Normal IGF-1
GH suppression (<1 ng/mL or <0.4 ng/mL depending on assay) after OGTT
Discordant:
Normal IGF-1 with elevated GH or vice versa
🔹 3. Clinical Classification Classic Acromegaly:
Overt physical features (enlarged hands, facial changes, etc.)
Subtle/Incipient Acromegaly:
Mild or non-specific features, often diagnosed via biochemical tests
🔹 4. Radiological Classification (MRI) Microadenoma: <10 mm
Macroadenoma: ≥10 mm
Can further be classified based on invasion (e.g., cavernous sinus invasion by Knosp grade)
🔹 5. Response to Treatment Biochemical control achieved with:
Surgery
Medical therapy (somatostatin analogues, GH receptor antagonists, dopamine agonists)
Radiotherapy
A study evaluates surgical outcomes for acromegaly at King's College Hospital(2012-2022), focusing on predictive factors for surgical cure. A novel radiological metric, the MI Ratio, is introduced to enhance the prediction of clinical remission post-surgery, providing a more accurate prognosis and informing treatment planning.
This single-centre cohort study involved a retrospective analysis of prospectively collected data from a UK tertiary referral centre. Included were patients with histologically proven somatotroph tumours who underwent endoscopic transsphenoidal surgery (TSS) between 2012 and 2022. Exclusions were made for incomplete data or lost follow-up. Patient demographics, tumour characteristics, radiological parameters, and biochemical markers were analysed. The MI Ratio was defined as the distance from the midline to the lateral maximum of a tumour, divided by the distance between the two cavernous carotid arteries on coronal MRI.
Out of 157 patients, 150 met the inclusion criteria. Using the 2018 consensus OGTT nadir < 0.40 ng/mL, microadenomas had a higher surgical cure rate (72%) compared to macroadenomas (48%), with an overall cure rate of 53%. Significant predictors of surgical cure included the MI Ratio (p < 0.001), microadenomas (p = 0.022), Knosp score < 2 (p = 0.012), immediate post-operative GH level (p = 0.016), and patient gender (p = 0.005). Pre-operative medical management did not significantly impact surgical remission (p = 0.19), while pre-operative GH level approached significance (p = 0.06). CV between operators for MI was < 5%, indicating minimal Interoperator variability.
This study is the first to describe the MI Ratio, demonstrating its utility in predicting surgical remission in acromegaly patients. A combination of radiological features, demographics, and hormone profiles can more accurately identify patients less likely to achieve surgical cure 2)
Etiology
Clinical features
Diagnosis
see Acromegaly diagnosis.
Treatment
see Acromegaly treatment.
Outcome
Books
This clinically oriented book will familiarize the reader with all aspects of the diagnosis of tumors and other disorders of the pituitary gland by means of magnetic resonance imaging (MRI). The coverage includes acromegaly, Cushing’s disease, Rathke cleft cysts, prolactinomas, incidentalomas, Clinically Non-Functioning Pituitary Neuroendocrine Tumors, other lesions of the sellar region, hypophysitis, and central diabetes insipidus. Normal radiologic anatomy and the numerous normal variants are described, and guidance is also provided on difficulties, artifacts, and other pitfalls. The book combines concise text and high-quality images with a question and answer format geared toward the needs of the practitioner. MRI is today considered the cornerstone in the diagnosis of diseases of the hypophyseal-hypothalamic region but the relatively small size of the pituitary gland, its deep location, the many normal anatomic variants, and the often tiny size of lesions can hinder precise evaluation of the anatomic structures and particularly the pituitary gland itself. Radiologists and endocrinologists will find MRI of the Pituitary Gland to be full of helpful information on this essential examination, and the book will also be of interest to internists and neurosurgeons.
Updates
Acromegaly is typically caused by a growth hormone-secreting pituitary neuroendocrine tumor, driving excess secretion of insulin-like growth factor 1. Acromegaly may result in a variety of cardiovascular, respiratory, endocrine, metabolic, musculoskeletal, and neoplastic comorbidities. Early diagnosis and adequate treatment are essential to mitigate excess mortality associated with acromegaly. PubMed searches were conducted using the keywords growth hormone, acromegaly, pituitary neuroendocrine tumor, diagnosis, treatment, pituitary surgery, medical therapy, and radiation therapy (between 1981 and 2021). The diagnosis of acromegaly is confirmed on biochemical grounds, including elevated serum insulin-like growth factor 1 and lack of growth hormone suppression after glucose administration. Pituitary magnetic resonance imaging is advised in patients with acromegaly to identify an underlying pituitary neuroendocrine tumor. Transsphenoidal pituitary surgery is generally first-line therapy for patients with acromegaly. However, patients with larger and invasive tumors (macroadenomas) are often not in remission postoperatively. Medical therapies, including somatostatin receptor ligands, cabergoline, and pegvisomant, can be recommended to patients with persistent disease after surgery. Select patients may also be candidates for preoperative medical therapy. In addition, primary medical therapy has a role for patients without mass effect on the optic chiasm who are unlikely to be cured by surgery. Clinical, endocrine, imaging, histologic, and molecular markers may help predict the response to medical therapy; however, confirmation in prospective studies is needed. Radiation therapy is usually a third-line option and is increasingly administered by a variety of stereotactic techniques. An improved understanding of the pathogenesis of acromegaly may ultimately lead to the design of novel, efficacious therapies for this serious condition 3)