• Diagnosis
  • Algorithms
  • Monitoring
  • Background
  • Lab Tests
  • References
  • Related Content

Indications for Testing

  • Adults
    • Chronic headaches or abnormal musculoskeletal growth (eg, increasing skull or chest size)
  • Children
    • Accelerated linear growth (gigantism)

Laboratory Testing

  • Concurrent fasting or random growth hormone (GH) and insulin-like growth factor 1 (IGF-1) levels
    • GH secretion is pulsatile and may or may not be elevated
      • Cannot be used as a single test in diagnosis
    • IGF-1 is usually elevated
      • Most important test – highly specific if elevated
    • GH <0.25 ng/mL and normal IGF-1 excludes acromegaly
    • Consensus criteria – nadir GH >0.53 ng/mL with high IGF-1 levels is diagnostic
  • If above criteria are not fulfilled, perform oral glucose tolerance test (OGTT) and measure GH
    • Administer 75 g glucose and perform GH measurements over 120 minutes
      • Failure to suppress GH during hyperglycemia is diagnostic
      • GH <1 ng/mL excludes acromegaly


  • Immunohistochemistry staining for growth hormone
    • May need to stain for other anterior pituitary hormones

Imaging Studies

  • MRI – preferred modality to evaluate adenoma presence and size

Differential Diagnosis

Acromegaly Testing Algorithm

  • Monitor growth hormone (GH) and insulin-like growth factor 1 (IGF-1) levels for effectiveness of therapy
    • Active disease
      • Random GH >1 ng/mL and nadir GH after oral glucose tolerance test (OGTT) ≥0.4 ng/mL
      • IGF-1 elevated
      • Also consider periodic MRI for active disease
    • Controlled disease
      • GH <1 ng/mL or nadir GH after OGTT <0.4 ng/mL
      • IGF-1 normal

Acromegaly is a rare chronic endocrine disorder resulting from hypersecretion of growth hormone (GH) by the pituitary gland.


  • Incidence – 3-4/million (Kannan 2013)
  • Age – mean onset 40 years
  • Sex – M:F, equal


  • Pituitary adenomas – most common cause
  • Tumors
  • Familial disorders
    • MEN1 (MEN1 gene)
    • McCune-Albright syndrome (GNAS gene)
    • Carney complex (PRKAR1A gene)
    • Familial isolated pituitary adenoma (AIP gene in 20%)
  • Extrapituitary causes
    • Growth hormone-releasing hormone (GHRH)-secreting hypothalamic tumor
    • Ectopic secretion of GHRH


  • Most acromegaly is caused by sporadic GH-secreting pituitary adenomas
  • GH is synthesized in the somatotroph cells of the anterior lobe of the pituitary gland
    • Pulsatile secretion
  • GH secretion is regulated by the hypothalamus
    • Stimulated by GHRH
    • Inhibited by somatostatin
  • Circulating GH stimulates synthesis and secretion of insulin-like growth factor 1 (IGF-1) from the liver
  • IGF-1 inhibits GH secretion at the pituitary and hypothalamus level, creating a negative feedback loop
  • Pituitary tumors mimic stimulation of adenylyl cyclase by GHRH receptor activation
    • Causes autonomous GH secretion
    • Symptoms are related to excess GH and IGF-1 secretion and to expansion of the pituitary mass

Clinical Presentation

  • Indolent course – delay in diagnosis of 4-10 years
  • Pituitary mass expansion symptoms
    • Headaches
    • Visual-field defects
    • Cranial nerve palsies
    • Symptoms consistent with hypopituitarism due to compression of remaining pituitary gland by the expanding mass
  • GH excess symptoms
    • Musculoskeletal
      • Hypertrophic arthropathy – both axial and peripheral skeleton
      • Carpal tunnel syndrome
      • Bony overgrowth
        • Coarse facial features, macrognathia, frontal bossing
        • Spade-shaped hands
        • Enlarged feet
        • Mandibular overgrowth – prognathism
        • Children with open epiphyses –  linear bone growth causes gigantism
      • Obstructive sleep apnea – due to soft tissue overgrowth (eg, macroglossia)
    • Cardiovascular
      • Hypertension
      • Cardiomyopathy – biventricular hypertrophy
      • Arrhythmias
    • Dermatologic
      • Acanthosis nigricans
      • Hyperhydrosis
    • Metabolic
    • Neoplastic
  • Familial acromegaly
    • MEN1
      • Autosomal dominant inheritance
      • ~10% incidence of GH-producing tumors
    • McCune-Albright syndrome
      • Rare
      • Triad of peripheral precocious puberty, café-au-lait spots, fibrous dysplasia of the bone
      • Thyrotoxicosis
    • Carney complex
      • Rare
      • Pigmented skin, myxoma, cardiac myxoma, thyroid nodules or carcinoma, primary pigmented nodular adrenocortical disease
      • ~10% incidence of GH-producing tumors
    • Familial isolated pituitary adenoma
      • More common for childhood onset
        • Frequent presentation is gigantism
      • Higher growth rate than with sporadic tumors

Indications for Laboratory Testing

Tests generally appear in the order most useful for common clinical situations.
Click on number for test-specific information in the ARUP Laboratory Test Directory

IGF-1 (Insulin-Like Growth Factor 1) 0070125
Method: Quantitative Chemiluminescent Immunoassay


Increased in pubertal and in pregnant patients

Growth Hormone 0070080
Method: Quantitative Chemiluminescent Immunoassay

Growth Hormone by Immunohistochemistry 2003929
Method: Immunohistochemistry

Additional Tests Available

Growth Hormone, 60 Minutes 0070083
Method: Quantitative Chemiluminescent Immunoassay

Growth Hormone, 120 Minutes 0070164
Method: Quantitative Chemiluminescent Immunoassay

IGF Binding Protein-3 0070060
Method: Quantitative Chemiluminescent Immunoassay


Use to evaluate short stature in children and for acromegaly

Use in conjunction with GH and IGF-1 testing


Chanson P, Bertherat J, Beckers A, Bihan H, Brue T, Caron P, Chabre O, Cogne M, Cortet-Rudelli C, Delemer B, Dufour H, Gaillard R, Gueydan M, Morange I, Souberbielle J, Tabarin A, Club Français De L'hypophyse (French Pituitary Club), Société Française Dendocrinologie (French Endocrinology Society). French consensus on the management of acromegaly. Ann Endocrinol (Paris). 2009; 70(2): 92-106. PubMed

Giustina A, Chanson P, Bronstein M, Klibanski A, Lamberts S, Casanueva F, Trainer P, Ghigo E, Ho K, Melmed S, Acromegaly Consensus Group. A consensus on criteria for cure of acromegaly. J Clin Endocrinol Metab. 2010; 95(7): 3141-8. PubMed

Kannan S, Kennedy L. Diagnosis of acromegaly: state of the art. Expert Opin Med Diagn. 2013; 7(5): 443-53. PubMed

Katznelson L, Laws E, Melmed S, Molitch M, Murad M, Utz A, Wass J, Endocrine Society. Acromegaly: an endocrine society clinical practice guideline. J Clin Endocrinol Metab. 2014; 99(11): 3933-51. PubMed

Melmed S, Colao A, Barkan A, Molitch M, Grossman A, Kleinberg D, Clemmons D, Chanson P, Laws E, Schlechte J, Vance M, Ho K, Giustina A, Acromegaly Consensus Group. Guidelines for acromegaly management: an update. J Clin Endocrinol Metab. 2009; 94(5): 1509-17. PubMed

General References

Bidlingmaier M, Strasburger C. Growth hormone assays: current methodologies and their limitations. Pituitary. 2007; 10(2): 115-9. PubMed

Capatina C, Wass J. 60 Years of Neuroendocrinology: Acromegaly. J Endocrinol. 2015; 226(2): T141-60. PubMed

Chanson P, Salenave S, Kamenicky P, Cazabat L, Young J. Pituitary tumours: acromegaly. Best Pract Res Clin Endocrinol Metab. 2009; 23(5): 555-74. PubMed

Chanson P, Salenave S. Acromegaly. Orphanet J Rare Dis. 2008; 3: 17. PubMed

Cordero R, Barkan A. Current diagnosis of acromegaly. Rev Endocr Metab Disord. 2008; 9(1): 13-9. PubMed

Tzanela M. Dynamic tests and basal values for defining active acromegaly. Neuroendocrinology. 2006; 83(3-4): 200-4. PubMed

Medical Reviewers

Last Update: January 2016