Acromegaly

What is acromegaly?

The clinical condition arising from excessive Growth hormone (GH) secretion in adults is called Acromegaly. GH secretion is characterized by blunting of pulsatile secretion and failure of GH to become undetectable during the 24 hour day, unlike normal individuals.

How common is it and what age group is affected?

  • Scientists estimate that about 3-4 out of every million people develop acromegaly each year.
  • 40 to 60 out of every million people suffer from the disease at any time.
  • Onset is insidious, therefore considerable delay between onset of clinical features & diagnosis
  • Most cases are diagnosed at 40 – 60 years.

Causes of Acromegaly

  • Pituitary adenomas (>99% of cases) Macroadenomas > Microadenomas
  • GHRH secretion
  • Hypothalamic secretion
  • Ectopic GHRH secretion e.g. Carcinoid tumors(pancreas, lung), Other neuroendocrine tumors
  • Ectopic GH secretion – Very rare

pituitary-4

Clinical features

  • Increased sweating
  • Headaches
  • Tiredness, lethargy
  • Joint pains
  • Change in ring or shoe size

Signs

  • Enlarged hands
  • Enlarged feet
  • Enlarged jaw (prognathism) and tongue
  • Thickening of the skin, skin tags
  • Easy fatigue
  • Excessive sweating
  • Limited joint mobility
  • Joint pain (hip pain, knee pain, ankle pain, foot pain, pain over the small joints of the foot, shoulder pain, elbow pain, wrist pain, hand pain, pain over the small joints of the hand, or pain in any other joint)
  • Carpal tunnel syndrome

Additional symptoms that may be associated with this disease

  • Weight gain (unintentional)
  • Hair, excessive on females

What are the investigations?

  • The level of growth hormone is high
    • A single value might be inconclusive. A GTT – GH is normally performed, where the patient is given 100gm of Glucose and blood samples are taken at baseline, I hour & 2 hourslater. We normally anticipate the Growth hormone levels to be below 2ng/ml when the sugar is high.
  • The level of IGF-1 (insulin-like growth factor 1) is high.
  • A spine X-ray shows abnormal bone growth.
  • A cranial MRI may show a pituitary tumor.

pituitary-5

This disease may also alter the results of the following

  • Other pituitary function test
  • Serum calcium- high
  • High sugar

What are the treatment options?

  • Surgery
    • If there is a pituitary adenoma resposible fot the tumor resection of the tumor is the best available option.
    • Reported cure rates vary 40-91% for microadenomas & 10-48% for macroadenomas
  • Radiotherapy
    • Reserved for patients with unsuccessful surgical treatment.
    • Largest fall in GH occurs in the first two years.
    • With a starting GH>50mU/L it takes on an average 6 years to achieve mean GH < 5mU/L compared to 4 years with GH<50mU/L.
  • Medical management
  • Somatostatin analogues
    • Usual dose is 50-200mcg SC thrice daily
    • Depot preparations can be given every 14 to 28 days
    • Can be used as primary therapy, before surgery or when surgery or radiotherapy have failed
  • Dopamine agonists
    • Particularly useful when there is coexistent prolactin secreting tumors
  • GH receptor antagonists (pegvisomant)
    • Normalistion of IGF 1 levels have been documented
    • More data required on tumor shrinkage

This article is prepared along with Dr Menaka