Acromegaly: The Multisystem Impact of Growth Hormone Excess, From Pituitary Pathophysiology to Modern Therapeutic Approaches

By: Nesredin Hassen Yesuf

LinkedIn | Email

Introduction

Acromegaly is a rare, chronic endocrine disorder caused by sustained overproduction of growth hormone (GH), typically due to a benign pituitary adenoma. The excess GH stimulates hepatic synthesis of insulin-like growth factor 1 (IGF-1), resulting in widespread tissue overgrowth and systemic complications [1].

Although distinct facial and skeletal changes eventually develop, the onset is gradual, and diagnosis often lags by several years. Early detection and appropriate treatment are crucial to prevent irreversible complications and normalize life expectancy [2].

Pathophysiology

In over 95% of cases, acromegaly is caused by a GH-secreting pituitary adenoma (somatotroph adenoma) [1]. Less commonly, ectopic secretion of GH or growth hormone–releasing hormone (GHRH) occurs.

Excess GH acts primarily on the liver to induce IGF-1 production, which mediates somatic and metabolic effects, including organ enlargement and insulin resistance. The GH–IGF-1 axis is normally controlled by hypothalamic somatostatin and GHRH, but this feedback is disrupted in adenomatous disease [3].

Figure 1: The GH–IGF-1 axis showing feedback control between hypothalamus, pituitary, liver, and others.

Clinical Features

The physical features of acromegaly evolve slowly, often noticed first by family members or through changes in ring or shoe size. Characteristic findings include enlarged hands and feet, coarse facial features, prognathism, and widened dental spacing [4].

Beyond these visible traits, acromegaly affects multiple organ systems:

• Cardiovascular: Hypertension and cardiomyopathy are major causes of mortality.

• Metabolic: Insulin resistance and diabetes mellitus occur in up to 50% of cases.

• Respiratory: Obstructive sleep apnea due to upper airway soft-tissue hypertrophy.

• Musculoskeletal: Arthropathy and carpal tunnel syndrome.

• Reproductive: Hypogonadism due to pituitary compression [5].

Figure 2: Comparison of normal and acromegalic facial changes.

Diagnosis

Diagnosis is based on elevated serum IGF-1 and lack of GH suppression during an oral glucose tolerance test (OGTT) [1,6]. Imaging with MRI of the pituitary confirms the presence and size of the adenoma.

Associated conditions such as diabetes, hypertension, and sleep apnea should be evaluated, as they influence both management and prognosis.

Management

The treatment goal is to normalize GH and IGF-1 levels, control tumor growth, and reverse symptoms.

• Surgery: Transsphenoidal resection remains first-line treatment, with remission in 60 - 80% of microadenomas [6].

• Medical therapy: Somatostatin analogues, dopamine agonists, and GH receptor antagonists are used when surgery is incomplete or contraindicated [7].

• Radiotherapy: Considered for residual or recurrent disease; modern stereotactic techniques have reduced side effects.

Figure 3: Diagnostic and therapeutic pathway for acromegaly, from screening to surgical and medical management.

Prognosis

Without treatment, acromegaly reduces life expectancy by nearly a decade, primarily from cardiovascular complications. Achieving biochemical remission restores survival rates to near normal [3]. Lifelong follow-up is recommended to monitor hormone levels and tumor recurrence.

Conclusion

Acromegaly exemplifies the profound systemic impact of a single hormonal excess. Although rare, its consequences span multiple organ systems, making early recognition essential. Advances in endoscopic surgery and targeted therapies have transformed the outlook for patients, turning a once-debilitating condition into a largely controllable one.

References

1. Giustina A, Biermasz N, Casanueva FF, Fleseriu M, Mortini P, Strasburger CJ, et al. Consensus on criteria for acromegaly diagnosis and remission. Pituitary. 2024;27(1):7–22. doi:10.1007/s11102-023-01360-1.

2. Lavrentaki A, Paluzzi A, Wass JAH, Karavitaki N. Epidemiology of acromegaly: review of population studies. Pituitary. 2017;20(1):4–9. doi:10.1007/s11102-016-0754-x.

3. Colao A, Grasso LFS, Giustina A, Melmed S, Chanson P, Pereira AM, et al. Acromegaly. Nat Rev Dis Primers. 2019;5(1):20. doi:10.1038/s41572-019-0071-6.

4. Melmed S. Acromegaly pathogenesis and treatment. J Clin Invest. 2009;119(11):3189–3202. doi:10.1172/JCI39375.

5. Katznelson L, Laws ER Jr, Melmed S, Molitch ME, Murad MH, Utz A, et al. Acromegaly: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2014;99(11):3933–3951. doi:10.1210/jc.2014-2700.

6. Freda PU. Monitoring of acromegaly: what should be performed when GH and IGF-1 levels are discrepant? Clin Endocrinol (Oxf). 2009;71(2):166–170. doi:10.1111/j.1365-2265.2009.03556.x.

7. Gadelha MR, Kasuki L, Korbonits M. Novel pathway for somatostatin analogs in patients with acromegaly. Trends Endocrinol Metab. 2013;24(5):238–246. doi:10.1016/j.tem.2012.11.007.

Assessed and Endorsed by the MedReport Medical Review Board