Acromegaly

Acromegaly is a disorder characterised by the excessive growth of certain body parts due to the overproduction of growth hormone (GH) after the growth plates have closed. It typically presents in middle age and is equally prevalent in both males and females. The primary cause is a benign tumour of the pituitary gland called a pituitary adenoma.

Lower jaw showing the classic spacing of teeth due to acromegaly.

Signs and Symptoms

The initial symptom of acromegaly is usually the enlargement of the hands and feet. Other physical manifestations include the enlargement of the forehead, jaw, and nose, as well as thicker skin and a deepened voice. Patients may also experience joint pain, headaches, and vision problems due to the expansion of the tumour. Complications can include type 2 diabetes, sleep apnoea, high blood pressure, and heart problems, such as cardiomyopathy.

Diagnosis

Diagnosis is primarily conducted through blood tests that measure GH and insulin-like growth factor I (IGF-1) levels. An oral glucose tolerance test is often used to confirm the diagnosis, as GH levels should be suppressed in normal individuals. Magnetic resonance imaging (MRI) is employed to detect the presence of a pituitary adenoma.

Frequent serum GH measurements in normal subjects (left panel) demonstrate that GH can fluctuate between undetectable levels most of the time interspersed with peaks of up to 30 μg/L (90 mIU/L); in acromegaly (right panel) GH hypersecretion is continuous with no undetectable levels.

Treatment

Surgery

Surgery is often the preferred treatment for acromegaly, particularly if the tumour is small. The goal is to remove the tumour and reduce GH levels to normal. Endonasal transsphenoidal surgery is the most common procedure, as it is less invasive and has a shorter recovery time than traditional transsphenoidal surgery.

Medications

If surgery is not successful or is contraindicated, medications such as somatostatin analogues, GH receptor antagonists, and dopamine agonists can be used. Somatostatin analogues like octreotide and lanreotide are effective in reducing GH levels and tumour size. GH receptor antagonists, such as pegvisomant, block the action of GH and are effective in controlling disease activity. Dopamine agonists like bromocriptine and cabergoline can also be used, especially in tumours that cosecrete prolactin.

Radiation Therapy

Radiation therapy is generally reserved for patients who have residual tumour post-surgery or who do not respond to medications. This therapy aims to reduce GH levels gradually over several years.

Site of action of the different therapeutic tools in acromegaly. Surgery, radiotherapy, somatostatin analogues and dopamine agonists act at the level of the pituitary adenoma, while GH receptor antagonists act in the periphery by blocking the growth hormone receptor and thus impairing the effects of GH on the different tissues.

Prognosis

With appropriate treatment, the life expectancy of acromegaly patients is generally comparable to that of the general population. However, without treatment, life expectancy is reduced by approximately 10 years. Successful treatment often alleviates many of the symptoms and complications associated with the disease, though certain conditions like sleep apnoea may persist.

Visual Indicators

Compared with the hand of an unaffected person (left), the hand of a person with acromegaly (right) is enlarged, with fingers that are widened, thickened and stubby, and with thicker soft tissue.

Mandibular overgrowth leads to prognathism, maxillary widening, teeth spacing and malocclusion.

Brow ridge and forehead protrusion remaining after tumour removal and tissue swelling eliminated.

Self-assessment MCQs (single best answer)

What is the primary cause of acromegaly?

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Which hormone is overproduced in acromegaly?

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Which of the following is not a common symptom of acromegaly?

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What test confirms the diagnosis of acromegaly after initial blood tests?

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Which medical imaging technique is used to identify a pituitary adenoma?

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Which surgical approach is less invasive for removing a pituitary tumour?

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What class of medication is octreotide, used in the treatment of acromegaly?

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Which of the following complications is not typically associated with acromegaly?

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What is the preferred treatment for acromegaly caused by a pituitary adenoma?

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What is the prognosis for acromegaly if left untreated?

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