acromegaly
ACROMEGALY
Acromegaly is a chronic, slowly developing disease with progressive disfigurement and disability. An early diagnosis is difficult as most signs and symptoms are due to long-standing overproduction of growth hormone &/or insulin-like growth factor (IGF-I) causing metabolic, endocrine and morphological changes.
Surgical intervention is the first-line of treatment for almost all patients with acromegaly unless there are contraindications or the patient refuses to undergo the procedure.

Definition

  • A chronic, slowly developing disease with progressive disfigurement and disability
  • An early diagnosis is difficult as most signs and symptoms are due to long-standing overproduction of growth hormone (GH) and/or insulin-like growth factor (IGF-I) causing metabolic, endocrine and morphological changes

Epidemiology

  • Uncommon disorder and in Europe, it has a prevalence of 30-70 individuals per million
  • Mean age of diagnosis is in the early to mid-40s in both males and females
  • Due to its insidious onset diagnosis is often delayed

Signs and Symptoms

Symptoms due to excess growth hormone (GH) and/or insulin-like growth factor (IGF-I):

  • Soft tissue swelling and extremities enlargement
  • Hyperhidrosis (excessive sweating)
  • Coarsening of facial features
  • Prognathism
  • Macroglossia
  • Arthritis
  • Gigantism
  • Increased incidence of obstructive sleep apnea
  • Increased incidence of diabetes mellitus (glucose intolerance)
  • Increased incidence of cardiovascular diseases [hypertension, coronary heart disease (CHD)]
  • Metabolic effects: Hyperphosphatemia, hypercalciuria, hypertriglyceridemia and low high-density lipoprotein-C (HDL-C)
  • Increased incidence of colonic polyps and adenocarcinoma of colon

Symptoms due to pressure caused by suprasellar extension of pituitary adenoma:

  • Visual field
  • Diplopia (secondary to cranial nerve palsy)
  • Headache
  • Loss of pituitary function resulting in lethargy, infertility and loss of libido

Pathophysiology

  • More than 95% of patients with acromegaly has hypersecretion of growth hormone & insulin-like growth factor-1 secondary to growth hormone-secreting pituitary adenoma that arise from somatotroph cells
    • In response to inducing signals including hypothalamic growth hormone-releasing hormone, growth hormone is synthesized and stored in the somatotroph cells (GHRH)
    • Production of growth hormone is suppressed by somatostatin signaling primarily through the somatostatin receptor subtype 2
    • Peripheral signals (eg insulin growth factor, steroid and paracrine growth factors) also regulates production of growth hormone
  • While <5% of patients with acromegaly have excess growth hormone secretion from a hypothalamic tumor or a neuroendocrine tumor that leads to somatotroph hyperplasia and acromegaly

Etiology

 Other Possible Causes of Acromegaly

  • Rarely, from ectopic pituitary tumor or ectopic production of growth hormone by other tumors like cancers of pancreas or lung
  • May also be caused by ectopic production of growth hormone (GHRH) by a tumor in the hypothalamus or tumors of the pancreas, kidney and lungs
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