Acromegaly

What is Acromegaly?

Acromegaly is a chronic metabolic disorder caused by the presence of too much growth hormone - GH and IGF-I hypersecretion. Growth hormone is a hormone secreted by the pituitary gland in response to GHRH secretion from the hypothalamus, and in excess it results in gradual enlargement of body tissues including the bones of the face, jaw, hands, feet, and skull.

Statistics on Acromegaly?

Incidence is 5.3 per 100000 per year.

Males and females are affected equally

Highest incidence in middle age (4th and 5th decades).

It is estimated that six years elapse between the onset of symptoms and the diagnosis.

Risk Factors for Acromegaly

The cause is usually a benign pituitary tumour (pituitary adenoma). Hyperplasia from excessive GHRH secretion from the hypothalamus is the other main cause but that is rare. There are no known risk factors for acromegaly other than a prior history of a pituitary tumor.

Progression of Acromegaly

The life expectancy of a patient with untreated acromegaly is 50 years, most due to a hypertrophic cardiomyopathy and malignant ventricular arrhythmias. Osteoporosis and fractures are frequent complications. Although glucose intolerance is common very few develop ketoacidosis or other significant complications of diabetes mellitus. The tumour may compromise visual fields. When it is adequately treated, life expectancy returns to normal and the other complications remit.

How is Acromegaly Diagnosed?

Blood glucose - elevated. Around 25% of patients have a diabetic glucose tolerance test.

Chest x-ray- may show cardiomegaly and osteoporosis.

Prognosis of Acromegaly

Indicators of disease severity:

Symptoms

Excessive sweating

Skin tags

Glycosuria

Hypertension

Increased loss of visual fieldsWhen effective controlis achieved the characteristic overgrowth and related symptoms reced and the metabolic abnormalities improve.

How is Acromegaly Treated?

Treatment is indicated in all except elderly or those with minmal abnormalities (untreated leads to markedly reduced survival). The Aim is to reduce mean growth hormone levels to below 5 mU/l.Surgery - treatment of choice in suitable cases - transsphenoidal or transfrontal if the tumour is large. Surgery is often combined with radiotherapy because excision is rarely complete with large tumours.External beam radiotherapy - normally used after pituitary surgery fails to normalize growth hormone levels rather than as primary therapy. May take 1-10 years to be effective when used alone.Drugs - subcutaneous octreotide or lanreotide (somatostatin analogues). Treatments of choice in resistant cases. Given to shrink tumours before definitve treatment or to control symptoms. Bromocriptine is usually reserved for eldery and frail people.

Acromegaly References

[1] Braunwald, Fauci, Kasper, Hauser, Longo, Jameson. Harrison's Principles of Internal Medicine. 15th Edition. McGraw-Hill. 2001[2] Cotran, Kumar, Collins 6th edition. Robbins Pathologic Basis of Disease. WB Saunders Company. 1999.[3] Haslett, Chilvers, Boon, Colledge. DAVIDSON'S PRINCIPLES & PRACTICE OF MEDICINE. Churchill Livingstone. 2002.[4] Hurst JW (Editor-in-chief). Medicine for the practicing physician. 4th edition Appleton and Lange 1996.[5] Kumar P, Clark M. CLINICAL MEDICINE. WB Saunders 2002 Pg 427-430.[6] Longmore M, Wilkinson I, Torok E. OXFORD HANDBOOK OF CLINICAL MEDICINE. Oxford Universtiy Press. 2001[7] MEDLINE Plus