Friday, 4 March 2016

Acromegaly (Gigantism)

Acromegaly, also known as gigantism, has the literal definition of enlargement of the body. It is most commonly caused by a gland tumour (adenoma) in the pituitary gland. This gland is located in the brain with the purpose of secreting growth hormones. Although, the tumour heightens the production of these growth hormones, the tumour itself is benign and therefore has little risk of developing into cancer.
Pituitary gland labelled

The adenoma can grow to 1cm in size which can exert pressure on cranial nerves in the brain and those leading to the eyes. Sufferers can therefore experience blurred vision and headaches.

The condition can be easily identified through physical diagnosis. It is characterised by very large hands, feet, toes and fingers with a prominent jawline and forehead also being common features caused by acromegaly.
Acromegaly common features
However, in order to certify the condition is present, a blood test can be carried out by testing the levels of growth hormone, which would normally decrease when the patient is given a sugary drink. Insulin-like growth factor 1 (IGF-1) is also tested. By it being produced by the liver, it provides an alternative cause for abnormal growth, therefore being liver damage.

The graph below shows that in non-sufferers, growth hormones are secreted predominantly during sleep. However, it is clear in the acromegaly sufferer's graph that GH levels keep at a constant level showing that the pituitary is secreting continuously. 
Graphs comparing Growth Hormone levels between sufferers and non-sufferers
A positive result for the growth hormone leads to MRI scans of the head to see whether there is a tumour present in the pituitary gland.
MRI scan of a Pituitary gland with a tumour
Acromegaly is rarely inherited but can be in the form of familial isolated pituitary adenoma or as part of multiple endocrine neoplasia (MEN). In familial isolate pituitary adenoma, the tumour growth occurs in adolescence, when the bones are still malleable enough for the excess growth hormones to make a significant effect.

The most effective treatment involves the surgical removal of the main cause of the condition, the tumour growth in the pituitary gland. Preferably, the adenoma should not be near any key structures of the brain, in order to limit possible complications during surgery.

An incision is first made under the nose or upper lip to allow an endoscope, and other surgical instruments, to access the sphenoid sinus, hence why it is defined as transsphenoidal surgery. The sinus space leads directly to the pituitary gland and therefore the adenoma. As a result, the tumour can be removed.
Transsphenoidal surgery

References:

nhsuk(2016)WwwnhsukRetrieved 04 March, 2016, from http://www.nhs.uk/conditions/acromegaly/Pages/Introduction.aspx

Nihgov(2016)NihgovRetrieved 04 March, 2016, from https://www.niddk.nih.gov/health-information/health-topics/endocrine/acromegaly/Pages/fact-sheet.aspx

Mayoclinicorg(2016)MayoclinicorgRetrieved 04 March, 2016, from http://www.mayoclinic.org/diseases-conditions/acromegaly/home/ovc-20177622

Hormoneorg(2016)HormoneorgRetrieved 04 March, 2016, from http://www.hormone.org/questions-and-answers/2012/acromegaly

No comments:

Post a Comment