Acromegaly - Human & Disease

Acromegaly

 

Acromegaly

(over-production of growth hormone)

Acromegaly develops when the pituitary gland releases too much GH into the body over a long period of time. When GH enters the blood, this signals the liver to produce another hormone, called insulin-like growth factor I (IGF-I). IGF-I is the hormone that actually causes bones and body tissue to grow.

- Acromegaly ( adult).

- Gigantism ( children).


Acromegaly (over-production of growth hormone) Acromegaly develops when the pituitary gland releases too much GH into the body over a long period of time. When GH enters the blood, this signals the liver to produce another hormone, called insulin-like growth factor I (IGF-I). IGF-I is the hormone that actually causes bones and body tissue to grow.
Acromegaly







What are the causes of acromegaly?

- Overproduction of growth hormone due to pitutary gland tumor or irritating lesion.

- Excess release of Insulin Like Growth Factor 1 (ILGF1).


History

¤ Enlargement of hands and feet

¤ Prognathism and loose teeth

¤ Increased sweating

¤ Sleep apnea and snoring

¤ Diabetes mellitus

¤ Coarsening change in facial appearance

¤ Frontal bossing

¤ Carpal tunnel syndrome

¤ Infertility

¤ Amenorrhea or oligoamenorrhea

¤ Family history of pituitary tumor

¤ Excessive linear growth (in children).

Acromegaly (over-production of growth hormone) Acromegaly develops when the pituitary gland releases too much GH into the body over a long period of time. When GH enters the blood, this signals the liver to produce another hormone, called insulin-like growth factor I (IGF-I). IGF-I is the hormone that actually causes bones and body tissue to grow.









Signs & Symptoms:

¤ Headache

¤ Arthralgias

¤ Impotence

¤ Skin tags

¤ Decreased libido

¤ Visual field cut

¤ Hypopituitarism

¤ Galactorrhea in some women.

What hormones cause acromegaly?

Acromegaly is a rare but serious medical condition that happens when you have high levels of growth hormone (GH) in your body. Your pituitary gland normally produces GH, but tumors on your pituitary or in other parts of your body produce excess GH in acromegaly.

Acromegaly (over-production of growth hormone) Acromegaly develops when the pituitary gland releases too much GH into the body over a long period of time. When GH enters the blood, this signals the liver to produce another hormone, called insulin-like growth factor I (IGF-I). IGF-I is the hormone that actually causes bones and body tissue to grow.










tests:

What are the blood tests for acromegaly?

Diagnosing acromegaly involves key blood tests:
 a test to check the level of the insulin-like growth factor-1 (IGF-1) and an oral glucose tolerance test (OGTT). Doctors can't simply test for the level of growth hormone (GH) in your body because the level varies so much in one day-even in someone without acromegaly.


A- Laboratory:

¤ Basic blood studies:

° Insulin-like growth factor-I (IGF-I) single best test

° growth hormone (GH) 1 h after 75-g glucose load: <5 ng/dL in normals

¤ Ancillary blood tests:

° LH, FSH, prolactin, free T4, TSH

° Testosterone

° Estradiol

° GH-releasing hormone

° Fasting serum glucose, HgA1c

B- Imaging:

¤ MRI of the pituitary to determine if there is pituitary mass.

Acromegaly (over-production of growth hormone) Acromegaly develops when the pituitary gland releases too much GH into the body over a long period of time. When GH enters the blood, this signals the liver to produce another hormone, called insulin-like growth factor I (IGF-I). IGF-I is the hormone that actually causes bones and body tissue to grow.












differential diagnosis:

 Acromegaly must be differentiated from other diseases that cause acral features like skin thickening and linear bone growth. These diseases such as:

¤ Marfan syndrome

¤ precocious puberty

¤ prolactinoma

¤ pachydermoperiostosis.

¤ GH-secreting pituitary tumor

¤ GH- and prolactin-secreting pituitary tumor.

¤ GH- or GHRH-secreting neuroendocrine tumor (e.g., islet cell tumor of the pancreas).

¤ Acromegaloidism:
acromegalic facies in patient with severe insulin resistance.

What is the difference between acromegaly and gigantism?

- Gigantism occurs when growth hormone hypersecretion occurs before the fusion of the long bone epiphysis and is characterized by tall stature.

- Acromegaly occurs when GH hypersecretion occurs after the fusion of the epiphysis leading to large extremities and characteristic facies.

Acromegaly (over-production of growth hormone) Acromegaly develops when the pituitary gland releases too much GH into the body over a long period of time. When GH enters the blood, this signals the liver to produce another hormone, called insulin-like growth factor I (IGF-I). IGF-I is the hormone that actually causes bones and body tissue to grow.











management:

How is acromegaly treated?

¤ Assess size and resectability of tumor.

specific therapy:

¤ Surgical resection of tumor (usually transsphenoidal), esp. if there is visual field cut.

¤ Medical therapy:

° Somatostatin analog (octreotide or long-acting octreotide) given parenterally; can normalize serum IGF-I and GH; some tumor shrinkage

¤ Dopamine agonists (bromocriptine or cabergoline): may lower IGF-I and GH in some cases; often require high doses.

¤ GH antagonists (pegvisomant) : very effective at lowering serum IGF-I; increases serum GH. Follow LFTs.

¤ Radiation therapy if surgery and medical therapy fail; may take up to 10 y to normalize serum IGF-I and GH; often causes hypopituitarism.

¤ Observation with repeated pituitary MRI to determine if tumor is growing.

¤ Left untreated, acromegaly can lead to worsening diabetes mellitus and hypertension. The disease also increases a patient's risk for CVS cardiovascular disease and colon polyps that may lead to cancer.

Treatment Goals:

¤ Normalize serum IGF-I level

¤ Normalize GH response to glucose load

¤ Diminish size of pituitary tumor

¤ Maintain normal pituitary function

¤ Fertility

¤ Cessation of galactorrhea

¤ Restoration of libido and potency.


Side Effects & Contraindications:

¤ Surgery and radiation: hypopituitarism

¤ Octreotide: gallstones and gastric upset

¤ Bromocriptine and cabergoline: gastric upset, nasal stuffiness,orthostatic hypotension with initial doses.

What drugs are approved for acromegaly?

Current FDA-approved treatments for acromegaly include drugs from several pharmacological classes including:

1- somatostatin analogs (octreotide, lanreotide, and pasireotide).

2- GH-receptor antagonist (pegvisomant).

3- Dopamine-receptor agonist (bromocriptine).


follow-up:

¤ Serum IGF-I postoperatively or 2 wks after changing dose of medicine.

¤ Repeat pituitary MRI after 3–6 mo. to assess pituitary growth.

complications and prognosis:
¤ Pituitary apoplexy (in patients with macroadenomas):
° Presents as very severe headache, altered consciousness, coma.

° Requires emergent surgical intervention and resection of tumor.

¤ Visual field changes signify tumor growth.

¤ Patients require lifelong observation.

¤ Increased risk of colonic polyps and perhaps colon cancer.

¤ Osteoarthritis

¤ Increased risk of early mortality (cardiac) if not cured (normal IGF-I levels).
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