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Acromegaly

Anisha ValliLeave a comment

Gigantism Versus Acromegaly

It is all about increase production of growth hormone and when the long bone in the leg, called the epiphysis plate, fuses. If the epiphysis plate has not fused before puberty and there is a large amount of growth hormone being released from the pituitary gland, the person is considered to have gigantism. If the epiphysis plate has fused after puberty and there is a large amount of growth hormone being released from the pituitary gland, the person is considered to have acromegaly. 

Long Bone diagram

Causes

  • PituitarySources: Somatotrope adenomas and mammosomatotrophe adenomas
  • Extra Pituitary Sources: Pancreatic adenoma (islet cell tumour) and excessive GnRh production by carcinoid tumor

Clinical Features

The peak occurrence of acromegaly is at age 40–45. Now that we understand how someone is diagnosed with acromegaly, let’s take a look at what a person would look like with this condition. Because the epiphysis bone has fused, they will not get taller, but bones and organs will enlarge.

They will have big hands, feet, and forehead:

  • ring tightening
  • increased shoe or glove size
  • frontal bossing

Their organs and glands will enlarge and cause associated diseases:

  • cardiomyopathy
  • left ventricular hypertrophy
  • diastolic dysfunction
  • colon polyps, and colonic malignancy.
  • an enlarged thyroid
  • Increase in sebum = oily skin
  • Peripheral resistance will increase = hypertension

Also, they could have an increase in blood glucose because the increase of growth hormone stops insulin from carrying the glucose out of the blood in to the tissues. So the glucose (sugar) hangs out in the blood. 

  • glucose intolerance
  • diabetes mellitus

Other unique features:

  • Thick heel pads
  • Deep voice
  • Hyperhidrosis
  • Skin tags
  • Osteoarthritis: bilateral limbs and weight gain
  • Spade like hand
  • Obstructive sleep apnea
  • Visual deficit
  • Carpal tunnel syndrome.

Oral Manifestations

  • Widened teeth spacing
  • mandibular enlargement with prognathism,
  • macroglossia

Overall mortality is increased approximately threefold.

Diagnosis

  • Insulin-like growth factor type I (IGF-I) levels are a useful screening measure with elevation suggesting acromegaly.
  • Investigation of choice: Due to the pulsatility of GH, measurement of a single random GH level is not useful for screening. The diagnosis of acromegaly is confirmed by demonstrating the failure of GH suppression to <0.4 μg/L within 1–2 h of a 75-g oral glucose load.
  • MRI of the pituitary usually reveals a macroadenoma.
  • Serum prolactin levels are increased in acromegaly
  • X-ray of Foot

Treatment

  1. The primary treatment modality for acromegaly is transsphenoidal surgery.
  2. GH levels are not normalized by surgery alone in many pts with macro-adenomas; in those, somatostatin analogues provide adjunctive medical therapy that suppresses GH secretion with modest to no effect on tumour size.
    Drugs: Octreotide, Lanreotide and Pasireotide
  3. The GH receptor antagonist pegvisomant can be added in pts who do not respond to somatostatin analogues. Pegvisomant is highly effective in lowering IGF-I levels but does not lower GH levels or decrease tumor size.
  4. Pituitary irradiation may also be required as adjuvant therapy but has a slow therapeutic onset and a high rate of late hypopituitarism.

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