Acromegaly: Overview and Pathophysiology

Acromegaly Overview

• Acromegaly is a rare condition, with approximately 3 cases per 1 million people diagnosed annually in the US.
• It affects both genders equally, with a mean age at diagnosis of 40-45 years.
• The cause is often a benign pituitary adenoma producing excess growth hormone (GH).

Pathophysiology and Clinical Manifestations

• Excess GH leads to soft tissue and bone overgrowth, particularly in the hands, feet, and face.
• Epiphyseal closure prevents lengthening of arms and legs.
• Manifestations develop slowly over years, potentially going unnoticed.
• Physical changes include thickening and enlargement of facial, foot, and head bones and tissues.
• Patients may experience proximal muscle weakness, joint pain (varying in severity), carpal tunnel syndrome, and peripheral neuropathy.
• Tongue enlargement impacts speech and dental health; deepened voice from vocal cord hypertrophy is also seen.
• Sleep apnea is possible due to upper airway narrowing.
• Skin thickening, oiliness, and acne are common.
• Vision changes can occur due to optic nerve pressure from a pituitary adenoma. Headaches are frequent.
• GH antagonizes insulin, leading to glucose intolerance and possible diabetes symptoms (increased thirst and urination).

Prognosis and Diagnostic Studies

• Reduced life expectancy (5-10 years) due to increased risk of cardiovascular disease, diabetes, and colorectal cancer.
• Joint pain and deformities may persist even with successful treatment.
• Diagnosis involves assessing plasma insulin-like growth factor-1 (IGF-1) levels and GH response to an oral glucose tolerance test (OGTT).
• IGF-1 reflects GH's peripheral actions, rising with GH levels though IGF-1 levels are more consistent than GH levels.
• During an OGTT, normal GH levels fall, while GH levels in acromegaly do not fall and may even rise.
• Imaging (MRI or CT scan) can detect pituitary adenomas.
• Complete eye exams, including visual field testing, are needed to assess possible optic nerve pressure.

Treatment and Interprofessional Care

• Treatment aims to restore normal GH levels through surgery, radiation, medication, or a combination.
• Surgery (hypophysectomy) is often the initial choice, especially for smaller tumors, to reduce GH levels immediately and reduce IGF-1 levels within weeks.
• Adjuvant therapies (radiation or medication) may be needed for larger tumors or higher GH levels.
• Medication options include somatostatin analogs (e.g., octreotide), dopamine agonists (e.g., bromocriptine), or GH antagonists (e.g., pegvisomant).
• Octreotide is administered subcutaneously thrice weekly; long-acting analogs (octreotide LAR, pasireotide, lanreotide) are given intravenously every four weeks.
• GH antagonists directly block the liver's IGF-1 production.
• Serial photos can support patient recovery.
• Psychosocial concerns (body image, sexuality, depression) and physical issues (fatigue, sleep disturbance) may persist, requiring patient support and/or referral to a support group.