Acromegaly is a relatively rare and complex disease, so its diagnosis is often overlooked for a decade or more. During the period between onset and diagnosis, complications develop that can lead to increased morbidity and mortality.
If acromegaly isn’t diagnosed in a timely manner and appropriate treatment initiated, a patient risks developing complications such as:
- bowel polyps
- cardiovascular disease
- type 2 diabetes mellitus
Therefore, it is important for clinicians to be aware of the clinical presentation of acromegaly and the diagnostic methods used to identify the condition.
Reaching a diagnosis of acromegaly involves a number of factors including a detailed patient history, a thorough clinical evaluation, awareness of the characteristic findings, and a number of investigational techniques including biochemical studies (e.g., blood tests to measure growth hormone [GH] and insulin-like growth factor-1 [IGF-1] levels, glucose tolerance test), radiologic scans, and other specialized tests.
Causes Create Signs & Symptoms
Over 95 percent of patients with acromegaly have a pituitary adenoma arising from somatotroph cells that hyper-secrete GH and IGF-1, which causes patients to show signs characterized by somatic overgrowth.
Among the signs and symptoms to look for are:
- coarseness and enlargement of facial features including the facial bones, lips, nose, and tongue
- hyperhidrosis and body odour
- deepened, husky voice
- skin tags
- coarse, oily, thickened skin
- thick body hair
- enlarged hands and feet
- enlarged chest due to growth of ribs
- joint pain and limited mobility
- muscle weakness
- degenerative arthritis
- vision changes
- loss of libido
- erectile dysfunction in men
- menstrual irregularities and breast discharge in women
Testing, Testing, Testing
Measurement of IGF-1 levels is recommended in patients with the typical clinical manifestations of acromegaly and in patients who don’t have the typical manifestations but who do have several of the conditions associated with acromegaly (such as sleep apnea, type 2 diabetes mellitus, debilitating arthritis, carpal tunnel syndrome, and hypertension). After adolescence, IFG-1 levels decrease with age, so all levels must be assessed in relation to age-appropriate normal values for the specific assay used.
Random sampling of serum GH isn’t enough to establish a diagnosis of acromegaly, because growth hormone secretion is subject to dual regulation by the hypothalamus. Growth hormone-releasing hormone (GHRH) stimulates growth hormone synthesis and release, but growth hormone-inhibiting hormone (GHIH) suppresses its release. GHIH secretion fluctuates; it increases during fasting, sleeping, and in obese people. Consequently, circulating growth hormone levels may reach high levels in healthy people at times, while patients with acromegaly may have levels in the normal range.
Arriving at a diagnosis of acromegaly includes measuring the levels of GH during a two-hour period after a standard 75g glucose load (glucose tolerance test) and assessing the peripheral biologic effect of hyper-secretion of GH as reflected by changes in IGF-1 levels.
Following a biochemical confirmation, MRI or CT imaging should be used to localize the site of excess hormone secretion. Pituitary MRI with administration of contrast material is the most sensitive imaging study for the determination of the source of excess growth hormone and is recommended to visualize tumour size and appearance. The MRI should be performed with 2mm slices to diagnose small microadenomas. If MRI is contraindicated or unavailable, CT scan is an acceptable alternative.
If there is no clear evidence of a pituitary adenoma, an ectopic tumour in the chest, abdomen, or pelvis should be considered as a possible source of the excessive growth hormone.
Additional tests may need to be performed in order to determine the extent that acromegaly has affected the patient, including echocardiography, colonoscopy, x-rays, assessment of bone mineral density, and sleep studies.
Making the Diagnosis
On average, primary care physicians diagnose about 40 percent of the cases of acromegaly. However, patients frequently consult other specialists and dentists for their symptoms and, consequently, they are treated for the presenting symptoms prior to getting a diagnosis for acromegaly. This can create a long delay in the start of appropriate therapy during which time significant complications can develop, increasing patients’ morbidity and mortality.
You can make a significant impact on your patients’ quality of life with the early diagnosis and prompt initiation of the right treatment. Learn more about acromegaly by taking free courses available at MDBriefCase.
Acromegaly: What Primary Care providers Need to Know
Looking for the zebra: ACROMEGALY. An uncommon cause behind common conditions!
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