- Acromegaly: a rare endocrinologic disease characterized by excess secretion of growth hormone (GH), resulting in a syndrome of coarsened facial features and overgrowth of the jaw, hands, and feet
- Gigantism: excessive GH secretion prior to fusion of epiphyseal growth plates in children and adolescents
Acromegaly most commonly presents between the ages of 40 and 45 years, but the diagnosis is typically delayed for 7 to 10 years after the onset of symptoms.
3 cases per million persons per year
60 to 480 cases per million persons
Etiology and Pathophysiology
- >90% of patients with acromegaly have a benign GH-secreting, or somatotroph, adenoma of the anterior pituitary.
- Excess secretion of GH stimulates the liver to secrete insulin-like growth factor 1 (IGF-1), which causes most of the condition’s clinical features.
- The remaining 10% have ectopic GH secretion, most commonly from pancreatic islet cell tumors or lymphomas, or hypersecretion of growth hormone–releasing hormone (GHRH), most commonly from hypothalamic gangliocytomas or peripheral neuroendocrine tumors such as carcinoid, islet cell tumors, small cell lung cancer, adrenal adenomata, medullary thyroid cancer, or pheochromocytoma (1).
- A majority may have a loss of expression of growth arrest and DNA-damage-inducible (GADD) 45 gamma peptide.
- 40% may have an activating mutation of the α-subunit of the guanine nucleotide stimulatory protein gene.
- In those undergoing genetic analysis, 4.4% found to have an overexpression mutation in GP101, an X-linked G protein–coupled receptor.
- Familial syndromes that include acromegaly as a feature, such as Carney syndrome, McCune-Albright syndrome, familial acromegaly, and multiple endocrine neoplasia type 1 (MEN1) are rare.
There are currently no preventive strategies for this condition.
Commonly Associated Conditions
- Sleep apnea, both central and obstructive
- Carpal tunnel syndrome
- Insulin resistance/impaired glucose tolerance/impaired fasting glucose/diabetes mellitus
- Thyroid disease/cancer
- Enlarging shoe and ring size
- Vision changes, particularly temporal hemianopsia
- Hand numbness/carpal tunnel syndrome
- Fatigue, weakness
- Sleep disturbance
- Increased sweating
- Oily skin
- Deepened voice
- Decreased libido
- Female: amenorrhea or other menstrual dysfunction, hot flashes, vaginal atrophy
- Male: erectile dysfunction
- Presentation may be subtle and is often aided by review of old photographs. Look for facial coarsening:
- Enlarging jaw (macrognathia), nose, and frontal bones
- Teeth spreading and change in bite/jaw malocclusion
- Enlarging tongue (macroglossia)
- Bitemporal hemianopsia
- Other cranial nerve defects
- Hypertrophic arthropathy of spine, hips, knees, ankles
- Vertebral fractures
- Gigantism (if pediatric or adolescent)
- Skin thickening, skin tags
- Visceromegaly: enlargement of the prostate (in men), kidneys, liver, spleen, heart, salivary glands, thyroid (goiter), and tongue
Diagnostic Tests & Interpretation
- Initial testing
- Serum IGF-1 (best single test for diagnosis; adjust for age). Levels 2 times the upper limit are more suggestive of acromegaly (2)[B].
- Falsely low IGF-1 may be seen in hypothyroidism, malnutrition, poorly controlled DM1, liver/renal failure, and oral estrogens; perform oral glucose tolerance test (OGTT).
- Concurrent laboratory findings
- Hyperprolactinemia; either through mass effect of the GH-secreting tumor or through prolactin/GH cosecretion
- Increased 25-hydroxyvitamin D
- Decreased sex hormone–binding globulin and thyroxine-binding globulin
- Follow-up testing
- A 75-g OGTT: In normal subjects, GH should drop to ≤1 ng/mL within 2 hours, but postglucose GH levels may remain >2 ng/mL in patients with acromegaly.
- MRI of the sella (with and without contrast)
- Will detect tumors as small as 2 mm in diameter
- Does not differentiate between functioning and nonfunctioning tumors
Follow-Up Tests & Special Considerations
If the sellar MRI is normal, perform a CT scan of the chest and abdomen to evaluate for extrapituitary source of acromegaly. Plasma GHRH should also be measured using a diagnostic threshold of 250 to 300 ng/L (1)[B].
- Goals of treatment:
- Decrease the serum IGF-1 level to within the reference range for the patient’s age and sex.
- Decrease the glucose-suppressed serum GH to <1 ng/mL.
- Ameliorate symptoms without causing other pituitary hormone deficiencies.
- Transsphenoidal surgery is the initial treatment of choice for most patients with acromegaly of pituitary origin, particularly if the tumor compresses the optic chiasm.
- Surgery is associated with higher remission rates when compared to primary medical management (3)[A].
A multidisciplinary team experienced in managing pituitary tumors is essential for treatment.
Pharmacologic treatment is generally used if inadequate response to surgery or poor surgical candidate:
- Primary medical therapy is with long-acting somatostatin analogs (octreotide, lanreotide).
- Dopamine agonist (cabergoline) may be used in combination with somatostatin analog.
- If above is ineffective, pegvisomant may be tried.
Somatostatin analogs (4
- Mechanism of action: Inhibit GH secretion.
- Octreotide: short-acting form: Initial dose is 50 μg SC q8h. If the serum IGF-1 concentration does not normalize within 1 to 2 months, titrate upward to a maximum dose of 500 μg SC q8h. Long-acting form: Initial dose is 10 mg IM q4wk, titrated up to 40 mg IM q4wk.
- Lanreotide: Initial dose is 60 to 90 mg SC q4wk, titrated to a normal IGF-1 level; if IGF-1 is normal on 60 or 90 mg SC q4wk, may attempt 120 mg q6wk or q8wk
- Dopamine agonist (cabergoline) (5)[A]
- Less efficacious than somatostatin analogs and is typically used in combination with somatostatin analogs
- Dose: 0.25 mg PO once weekly, titrated to a maximum dose of 1 mg PO twice weekly
- Side effect: nausea
- GH-receptor antagonist (pegvisomant)
- Use if acromegaly has not responded to other treatments.
- Dose: initial loading dose of 40 mg SC and then 10 mg SC daily, titrated to a maximum maintenance dose of 30 mg/day
- Side effects: elevated serum aminotransferases
- Estrogen or selective estrogen receptor modulators (SERMS) (raloxifene and tamoxifen) (6)[B]
- Likely effective only in females
- Estrogens more potent in IGF-1 reduction than are SERMS
- GH and IGF-1 increase risk for gestational diabetes and gestational hypertension.
- Pregnant women with acromegaly would benefit from endocrinology and MFM referrals.
- Test visual fields at end of the 1st trimester and then every 6 weeks.
- Consider MRI without contrast if new symptoms develop or visual field testing suggests chiasmal lesion.
- If planned pregnancy, consider discontinuing long-acting somatostatin.
- Used if acromegaly is uncontrolled by surgery or medical therapy
- Conventional, proton beam, and stereotactic radiotherapy have been used.
- Complication: hypopituitarism (50%)
- Transsphenoidal surgical resection by an experienced neurosurgeon is the treatment of choice for patients with pituitary tumors that are resectable.
- If serum IGF-1 is normalized after surgery (within 7 to 10 days after resection), no further therapy is recommended.
Monitoring for medical and surgical treatment:
- At baseline
- Every 3 to 4 months
- Cardiovascular exam and BP measurement
- Measurement of serum IGF-1
- Patients with complications (cardiomyopathy, sleep apnea, colon polyps) should be followed appropriately according to guidelines for these conditions.
- Specifically after surgical resection: random IGF-1, GH level, and pituitary MRI performed 12 weeks
Pituitary Patient Resource Guide, published by the Pituitary Network Association (www.acromegaly.org)
- Patients with GH levels <2.5 after treatment have a mortality similar to the general population (5).
- Death is primarily caused by cancer (15%), respiratory diseases (25%), and cardiovascular diseases (60%).
- If untreated, there is an associated 30% decrease in lifespan related to the above complications.
See section on “Commonly Associated Conditions.”
- Dekkers OM, Biermasz NR, Pereira AM, et al. Mortality in acromegaly: a metaanalysis. J Clin Endocrinol Metab. 2008;93(1):61–67. [PMID:17971431]
- Melmed S. Medical progress: acromegaly. N Engl J Med. 2006;355(24):2558–2573. [PMID:17167139]
- Pita-Gutierrez F, Pertega-Diaz S, Pita-Fernandez S, et al. Place of preoperative treatment of acromegaly with somatostatin analog on surgical outcome: a systematic review and meta-analysis. PLoS One. 2013;8(4):e61523. [PMID:23634209]
- Wolinski K, Czarnywojtek A, Ruchala M. Risk of thyroid nodular disease and thyroid cancer in patients with acromegaly—meta-analysis and systematic review. PLoS One. 2014;9(2):e88787. [PMID:24551163]
- E22.0 Acromegaly and pituitary gigantism
- 253.0 Acromegaly and gigantism
- 230581008 Neuropathy in acromegaly (disorder)
- 240089002 Myopathy in acromegaly (disorder)
- 267386008 Gigantism and acromegaly
- 74107003 Acromegaly (disorder)
- 80849007 Gigantism (disorder)
- The onset of acromegaly is insidious and may be initially subtle.
- The serum IGF-1 level is the preferred screening test and is elevated in acromegaly.
- An elevated IGF-1 should prompt an MRI of the pituitary.
- First-line treatment of acromegaly is generally transsphenoidal surgery for resectable tumors, followed by long-acting somatostatin analogues, GH-receptor antagonists, and/or radiotherapy if surgery alone is not effective at reducing IGF-1 levels to normal.
Julie A. Creech, DO
Christine M. Broszko, MD
- Borson-Chazot F, Garby L, Raverot G, et al; for GTE Group. Acromegaly induced by ectopic secretion of GHRH: a review 30 years after GHRH discovery. Ann Endocrinol (Paris). 2012;73(6):497–502. [PMID:23122576]
- Subbarayan SK, Fleseriu M, Gordon MB, et al. Serum IGF-1 in the diagnosis of acromegaly and the profile of patients with elevated IGF-1 but normal glucose-suppressed growth hormone. Endocr Pract. 2012;18(6):817–825. [PMID:22784832]
- Abu Dabrh AM, Mohammed K, Asi N, et al. Surgical interventions and medical treatments in treatment-naïve patients with acromegaly: systematic review and meta-analysis. J Clin Endocrinol Metab. 2014;99(11):4003–4014. [PMID:25356809]
- Murray RD, Melmed S. A critical analysis of clinically available somatostatin analog formulations for therapy of acromegaly. J Clin Endocrinol Metab. 2008;93(8):2957–2968. [PMID:18477663]
- Sandret L, Maison P, Chanson P. Place of cabergoline in acromegaly: a meta-analysis. J Clin Endocrinol Metab. 2011;96(5):1327–1335. [PMID:21325455]
- Stone JC, Clark J, Cuneo R, et al. Estrogen and selective estrogen receptor modulators (SERMs) for the treatment of acromegaly: a meta-analysis of published observational studies. Pituitary. 2014;17(3):284–295. [PMID:23925896]
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