What Is Acromegaly?
Growth hormone (GH) is a protein substance released by the pituitary gland. It’s responsible for organ and tissue growth and development. The alteration in GH concentration can cause acromegaly or gigantism. Learn more about this pathology below.
Acromegaly is a metabolic endocrine disease characterized by excess growth hormone release. Elevated GH levels in childhood promote the development of gigantism. Studies affirm that acromegaly has a worldwide prevalence of 60 cases per million inhabitants.
This condition generally doesn’t vary by gender, race, or ethnicity. Symptoms usually begin after the age of 30, however, the average age of diagnosis is around 40 years, due to the low suspicion of this disease. Prompt treatment reduces the risk of complications and improves quality of life.
Symptoms of acromegaly
Acromegaly is a chronic and progressive pathology that begins after the closure of the growth plates in the long bones. The excess of GH promotes the abnormal development of soft tissues and the alteration of facial features. Some of the signs that are evident in acromegaly are the following:
- Widening of the nose
- Jaw protrusion
- Bulging of the forehead
- Prominent cheekbones
- Separation of the teeth
- Increase in the size of the hands and feet
- Increase in the volume of the tongue or macroglossia
Similarly, it’s common for the person to have rough, oily, and thick skin, as well as excessive sweating. Other general manifestations of this pathology are the following:
- A harsh, low-pitched voice
- Fatigue and muscle weakness
- Snoring
- Persistent headaches
- Visual problems
- Limited joint movement
Causes
The pituitary gland is a small neuroendocrine organ located at the base of the skull. This is responsible for secreting various hormones and regulating the functioning of various endocrine axes such as ovulation. GH is synthesized and released from the somatotropic cells of the pituitary.
Acromegaly is the result of chronic excessive GH production and release in adults. This hormone is capable of increasing protein synthesis and tissue growth. In addition, it promotes the secretion of insulin-like growth factor type 1 (IGF-1), which is responsible for the development of soft tissue and bones.
Research (article in Spanish) affirms that more than 98% of acromegaly cases are the result of a pituitary adenoma. This is a type of benign tumor that compresses the pituitary structures, increasing the production of GH and other hormones. Similarly, tumor compression also causes headaches and visual disturbances.
On the other hand, acromegaly is also the result of GH-secreting tumors located in the lung or pancreas. In addition, these types of tumors have the ability to synthesize growth hormone-releasing hormone (GHRH). This molecule activates GH release directly in the pituitary.
Complications of acromegaly
Elevated levels of GH in the body can have serious long-term consequences. Cardiovascular complications affect half of the people with acromegaly. High blood pressure, hypertrophic heart disease, arrhythmias, and coronary heart disease are some of the most common complications.
On the other hand, affected people can develop various pulmonary, joint, neurological and endocrine metabolic conditions over time. Among the main complications of acromegaly are the following:
- Obstructive sleep apnea and respiratory failure
- Joint pain and vertebral fractures
- Carpal tunnel syndrome
- Thyroid enlargement
- Colonic polyps and colorectal cancer
- Type 2 diabetes
- Increased triglycerides
Similarly, some patients may suffer psychological changes. These include decreased libido, anxiety, depression, and dementia. The lack of timely treatment can promote a deterioration in the quality of life and premature death.
Diagnosis
The diagnosis of acromegaly is based on the detection of the classic manifestations of the disease and their confirmation by complementary studies. In this sense, the doctor must consider the personal and family history of the person, as well as the findings of a physical examination.
Similarly, the measurement of GH and IGF-1 levels in the blood constitute the basis for the diagnosis of this condition. The GH concentration in normal adults is almost undetectable. On the other hand, an IGF-1 value between 122 and 400 nanograms per milliliter rules out acromegaly.
Some studies suggest that the GH suppression test with oral glucose load is the gold standard for the identification of this entity. In it, GH levels are measured before and after the administration of 75 grams of glucose. It is normal when GH suppression is detected below 1 nanogram per milliliter.
Sometimes it’s necessary to measure IGF-1 transporter protein 3 and growth hormone-releasing hormone levels. In addition, it’s useful to carry out other complementary analyzes such as the following:
- Blood sugar levels
- Prolactin test
- Computerized axial tomography (CT)
- Nuclear magnetic resonance (NMR)
- Echocardiography and colonoscopy
Treatment
The main objective of the treatment of acromegaly is to achieve remission of symptoms and control the tumor lesion without altering the function of the pituitary. Similarly, the aim is to reduce GH levels below 1 nanogram per milliliter in the oral glucose load test.
The treatment plan varies according to the severity of the patient’s medical history, the age and general condition of the patient, as well as the location and size of the tumor. Treatment options include surgery and radiation therapy to shrink the tumor mass, as well as medications to lower GH levels.
Surgery
This is the first line of therapy in most people with acromegaly. Tumor removal allows GH levels to return to normal and reduces symptoms associated with the compression of adjacent tissues.
Transsphenoidal endoscopy is the most widely used method for the extraction of pituitary lesions. Nasal congestion, sinusitis, and nasal bleeding are some of the complications associated with this procedure. However, it has a high success rate and the mortality rate is very low.
Medicine
The use of drugs is recommended in patients who aren’t candidates for surgery or in people whose condition persists after surgery. The most commonly used drugs for acromegaly are the following:
- Somatostatin agonists: These work by reducing the synthesis and release of GH in the pituitary gland. Octreotide, or Sandostatin, and Lanreotide, or Somatuline Depot, are some of the formulations used. They’re generally administered intramuscularly or subcutaneously.
- Growth hormone antagonists: These are synthetic GH analogs that block specific receptors for this substance and prevent its activation. Pegvisomant, or Somavert, is the main representative of this group. It’s administered subcutaneously and reduces IGF-1 levels.
- Dopamine agonists: These are drugs capable of reducing GH and IGF-1 concentrations. Cabergoline and bromocriptine are high-dose oral drugs capable of reducing the size of tumor lesions. They’re usually used alone or in combination with any of the above medications.
Radiotherapy
Radiation therapy is used as adjuvant therapy in people in whom the disease persists after surgery. In addition, it’s useful when medications don’t offer good results or aren’t recommended. It works by destroying tumor cells and consequently decreasing GH levels.
Radiation therapy methods include conventional and stereotactic methods. The latter is the most recommended, as a single dose is applied and has fewer adverse effects.
A condition that must be detected early
Acromegaly is a rare disease associated with elevated GH levels in adults. Characteristic symptoms include alterations in facial features and abnormal growth of the hands and feet. Lack of treatment can promote several long-term complications that put people’s lives at risk.
Given the evidence of the classic symptoms of this condition, it’s vital to seek medical attention. Health experts are the only ones trained to assess this disease and offer the best guidance in relieving symptoms.
- Rojas-Zalazar D, Mura C J, Cataldo G C, Wohllk G N. Manejo multidisciplinario de la acromegalia. Rev. chil. neuro-psiquiatr. 2011 Mar ; 49( 1 ): 37-46.
- Mercano M. Complicaciones sistémicas de la acromegalia. Rev. Venez. Endocrinol. Metab. 2006 Oct; 4( 3 ): 006-006.
- González-Houdelath K. Acromegalia. Revista Medica Sinergia. 2020;5(7):e540.
- Chanson P, Salenave S. Acromegaly. Orphanet J Rare Dis. 2008 Jun 25;3:17.
- Melmed S. Acromegaly pathogenesis and treatment. J Clin Invest. 2009 Nov;119(11):3189-202.
- Lavrentaki A, Paluzzi A, Wass JA, Karavitaki N. Epidemiology of acromegaly: review of population studies. Pituitary. 2017 Feb;20(1):4-9.
