Acral growth

Specialty: Endocrine and metabolic.

• enlargement of limbs and jaw
• rough facial features of acromegaly
• prognathism and widening of hands and feet

Why it occurs

• Growth hormone-producing pituitary adenoma (autonomously GH-producing pituitary somatotropinoma, stimulating sustained hepatic production of IGF-1)
• Hyperplasia of pituitary somatotroph cells due to ectopic secretion of GHRH of tumor origin (bronchial or pancreatic carcinoid tumors)
• Familial acromegaly in the context of Multiple Endocrine Neoplasia syndrome type 1 or Carney complex

Initial workup

Basal determination of insulin-like growth factor type 1 (IGF-1) in serum, rigorously adjusted for age and sex (it is the best screening test due to its plasma stability); 75-gram oral glucose tolerance test (OGTT) with serial measurements of growth hormone (GH) every 30 minutes for 2 hours, where absence of GH suppression below 0.4 mcg/L or 1.0 mcg/L confirms acromegaly; gadolinium magnetic resonance imaging of the sella turcica; and transthoracic echocardiogram.

Standard management

• Extended-release octreotide — first-line synthetic somatostatin analog that binds to pituitary sst2 receptors to inhibit GH secretion and reduce tumor size, administered deep intramuscularly every 4 weeks
• Pegvisomant — growth hormone receptor antagonist that blocks peripheral signal transduction and effectively reduces IGF-1 levels, of choice in refractoriness to somatostatin analogues
• Cabergoline — dopamine D2 receptor agonist that can be prescribed as an adjuvant in mixed tumors with prolactin secretion or in cases of mild acromegaly with slightly elevated IGF-1
• Lanreotide — long-acting somatostatin analog administered by deep subcutaneous injection