- What is Acromegaly?
- Today we will discuss a unique disorder that has been around since ancient times- ‘Acromegaly’. This is a combination of ancient French and Greek words- Acro meaning extremity, tip, end or peak’ and “megaly” meaning an abnormal enlargement.
- Today in Medicine, Acromegaly refers to an abnormal growth of the body due to an overproduction of growth hormone by the pituitary gland in the brain.
History of Acromegaly
In 1886, Pierre Marie coined the term ‘acromegaly’.
In 1909, Dr. Cushing postulated the cause as excessive secretion of growth-promoting hormone by a hyper-functioning pituitary gland
After 1970, medical therapies were developed, inclusive of dopamine agonists, somatostatin analogues and GH receptor blockers.
Today, treatment via surgery -transsphenoidal resection of the pituitary and radiotherapy are also utilized.
What is the pathophysiology of Acromegaly?
The pathophysiology of Acromegaly is extraordinarily complex, it involves excess secretion of growth hormone. This hormone induces the synthesis of peripheral Insulin Like Growth Factor 1 (IGF). This then leads to cell proliferation and hence enlargement of tissues and organ systems.
What are the clinical features of Acromegaly?
Acromegaly is an interesting disorder, and it presents insidiously over 5 to 10 years. The effects can be local due to tumor compression or systemic because of growth hormone on various body tissue. For example, swelling, arthralgias, jaw enlargement, fasting hyperglycemia, sweating, large tongue, osteoarthritis, frontal bossing, enlarged heart leading to heart failure.
Acromegaly is a high yield topic for USMLE, so grouping the clinical features is extremely useful:
- LOCAL TUMOUR EFFECTS:
- Pituitary enlargement causing headaches
- Vision problems- bitemporal hemianopia
- SOMATIC SYSTEM:
- Acral enlargement
- Arthralgias and arthritis
- Carpel tunnel syndrome
- Muscle weakness
- Hyperhidrosis Visceromegaly:
- Tongue (macroglossia)
- Thyroid gland (Goiter-neck pain)
- Kidney (causing back pain)
- Liver enlargement- (hepatomegaly causing RUQ pain)
- Spleen- (splenomegaly causing LUQ pain)
- Prostate (prostamegaly) CARDIOVASCULAR:
- Heart Enlargement- leading to heart failure
- Cardiomyopathy RESPIRATORY:
- Shortness of breath
- Sleep apnea
- Colonic polyps Reproductive:
- Menstrual abnormalities
- Decreased sex drive (libido) METABOLIC
- Diabetes Mellitus due to insulin resistance
- Lipid derangements
The diagnosis of Acromegaly is made by measuring IGF-1. The American Endocrinology Society recommends that a serum IGF-1 level be measured in patients with clinical features suggestive of Acromegaly.
Please note that a random GH measurement is not considered useful in diagnosis because of the lack of a well-defined normal range.
Normally, serum [GH] falls to ≤1 ng/mL in 2 hours after ingestion of 75 g glucose.
But in acromegaly, the values are >2 ng/mL in over 85% of patients.
It is important to establish clear goals for treatment, these include:
- To control the metabolic effects of GH and IGF-1
- To shrink the tumor size
- To prevent local mass effects
- To reduce signs and symptoms of Acromegaly (Aesthetics)
- To improve medical comorbidities e.g., Diabetes Mellitus and hypertension
- To prevent death
As mentioned earlier the primary treatment modality is surgery, which is recommended for all microadenomas and macroadenomas with mass effect. Medical therapy is mostly used in the adjuvant setting following surgery.
- The prognosis is excellent with most patients having a 5-year survival of over 90% with treatment.