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{{Acromegaly}}
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==Overview==
==Overview==
An elevated concentration of serum [[Growth hormone|growth hormone (GH)]] and [[Insulin-like growth factor|insulin-like growth factor 1(IGF-1)]] levels is diagnostic of acromegaly.
==Laboratory Findings==
==Laboratory Findings==
*Laboratory findings consistent with the diagnosis of acromegaly include:
**Elevated [[Insulin-like growth factor|Insulin Growth Factor 1 (IGF-1) level]]:<ref name="pmid25356808">{{cite journal| author=Katznelson L, Laws ER, Melmed S, Molitch ME, Murad MH, Utz A et al.| title=Acromegaly: an endocrine society clinical practice guideline. | journal=J Clin Endocrinol Metab | year= 2014 | volume= 99 | issue= 11 | pages= 3933-51 | pmid=25356808 | doi=10.1210/jc.2014-2700 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=25356808  }} </ref><ref name="pmid492275">{{cite journal| author=Clemmons DR, Van Wyk JJ, Ridgway EC, Kliman B, Kjellberg RN, Underwood LE| title=Evaluation of acromegaly by radioimmunoassay of somatomedin-C. | journal=N Engl J Med | year= 1979 | volume= 301 | issue= 21 | pages= 1138-42 | pmid=492275 | doi=10.1056/NEJM197911223012102 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=492275  }} </ref>
***IGF-1 level measurement is one of the best laboratory tests to diagnose acromegaly. The IGF-1 level is elevated in all patients with acromegaly. 
***IGF-1 measurement has been recommended in the patients with acromegaly clinical features.
***IGF-1 measurement has been recommended in the patients who do not have the typical acral features but have associated conditions like [[sleep apnea]] and [[carpal tunnel syndrome]] to confirm or exclude acromegaly. 
***IGF-1 level is measured also in the patients with only [[pituitary adenoma]] to exclude acromegaly.
***IGF-1 is affected by some factors as the age of the patient, [[genes]], [[sex hormones]] and [[steroids]]. Although it is one of the best lab tests to diagnose acromegaly, it is not used alone in the diagnosis. Therefore, measurement of the [[growth hormone]] is recommended when the [[IGF-1]] level is elevated.<ref name="pmid16932333">{{cite journal| author=Clemmons DR| title=Clinical utility of measurements of insulin-like growth factor 1. | journal=Nat Clin Pract Endocrinol Metab | year= 2006 | volume= 2 | issue= 8 | pages= 436-46 | pmid=16932333 | doi=10.1038/ncpendmet0244 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16932333  }}</ref>
***False results of IGF-1 levels may occur in some cases like [[hypothyroidism]], [[renal failure]], [[Liver failure|liver cell failure]] and uncontrolled [[diabetes mellitus]].
**Elevated [[Growth hormone|Growth Hormone]] (GH) level after [[OGTT|Oral Glucose Tolerance Test (OGTT)]]:<ref name="pmid19033371">{{cite journal| author=Carmichael JD, Bonert VS, Mirocha JM, Melmed S| title=The utility of oral glucose tolerance testing for diagnosis and assessment of treatment outcomes in 166 patients with acromegaly. | journal=J Clin Endocrinol Metab | year= 2009 | volume= 94 | issue= 2 | pages= 523-7 | pmid=19033371 | doi=10.1210/jc.2008-1371 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19033371  }}</ref>
***[[Oral glucose gel|Oral glucose]] normally suppresses the [[growth hormone]] secretion. The level of growth hormone after administration of 75mg glucose decreases to less than  1 ng/ml.
***In patients with acromegaly, administrations of the oral glucose will not suppress the [[GH]] secretion. Hereby, [[Glucose tolerance test|oral glucose tolerance test]] is one of the best laboratory confirming tests of acromegaly.
***It is recommended to measure the [[growth hormone]] level before and after administration of [[glucose]]. [[GH]] level is measured after two hours of the administration and the diagnostic level is more than ng/ml.<ref name="pmid17167139">{{cite journal| author=Melmed S| title=Medical progress: Acromegaly. | journal=N Engl J Med | year= 2006 | volume= 355 | issue= 24 | pages= 2558-73 | pmid=17167139 | doi=10.1056/NEJMra062453 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17167139  }} </ref>


If acromegaly is suspected, a doctor must measure the GH level in a person’s blood to determine if it is elevated. However, a single measurement of an elevated blood GH level is not enough to diagnose acromegaly: Because GH is secreted by the pituitary in impulses, or spurts, its concentration in the blood can vary widely from minute to minute. At a given moment, a person with acromegaly may have a normal GH level, whereas a GH level in a healthy person may even be five times higher.
==References==
 
{{reflist|2}}
More accurate information is obtained when GH is measured under conditions that normally suppress GH secretion. Health care professionals often use the oral glucose tolerance test to diagnose acromegaly because drinking 75 to 100 grams of glucose solution lowers blood GH levels to less than 1 nanogram per milliliter (ng/ml) in healthy people. In people with GH overproduction, this suppression does not occur. The oral glucose tolerance test is a highly reliable method for confirming a diagnosis of acromegaly.
 
Physicians also can measure IGF-I levels, which increase as GH levels go up, in people with suspected acromegaly. Because IGF-I levels are much more stable than GH levels over the course of the day, they are often a more practical and reliable screening measure. Elevated IGF-I levels almost always indicate acromegaly. However, a pregnant woman’s IGF-I levels are two to three times higher than normal. In addition, physicians must be aware that IGF-I levels decline with age and may also be abnormally low in people with poorly controlled diabetes or liver or kidney disease.


==References==
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Latest revision as of 21:59, 24 August 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

Overview

An elevated concentration of serum growth hormone (GH) and insulin-like growth factor 1(IGF-1) levels is diagnostic of acromegaly.

Laboratory Findings

  • Laboratory findings consistent with the diagnosis of acromegaly include:
    • Elevated Insulin Growth Factor 1 (IGF-1) level:[1][2]
      • IGF-1 level measurement is one of the best laboratory tests to diagnose acromegaly. The IGF-1 level is elevated in all patients with acromegaly.
      • IGF-1 measurement has been recommended in the patients with acromegaly clinical features.
      • IGF-1 measurement has been recommended in the patients who do not have the typical acral features but have associated conditions like sleep apnea and carpal tunnel syndrome to confirm or exclude acromegaly.
      • IGF-1 level is measured also in the patients with only pituitary adenoma to exclude acromegaly.
      • IGF-1 is affected by some factors as the age of the patient, genes, sex hormones and steroids. Although it is one of the best lab tests to diagnose acromegaly, it is not used alone in the diagnosis. Therefore, measurement of the growth hormone is recommended when the IGF-1 level is elevated.[3]
      • False results of IGF-1 levels may occur in some cases like hypothyroidism, renal failure, liver cell failure and uncontrolled diabetes mellitus.
    • Elevated Growth Hormone (GH) level after Oral Glucose Tolerance Test (OGTT):[4]
      • Oral glucose normally suppresses the growth hormone secretion. The level of growth hormone after administration of 75mg glucose decreases to less than 1 ng/ml.
      • In patients with acromegaly, administrations of the oral glucose will not suppress the GH secretion. Hereby, oral glucose tolerance test is one of the best laboratory confirming tests of acromegaly.
      • It is recommended to measure the growth hormone level before and after administration of glucose. GH level is measured after two hours of the administration and the diagnostic level is more than ng/ml.[5]

References

  1. ↑ Katznelson L, Laws ER, Melmed S, Molitch ME, Murad MH, Utz A; et al. (2014). "Acromegaly: an endocrine society clinical practice guideline". J Clin Endocrinol Metab. 99 (11): 3933–51. doi:10.1210/jc.2014-2700. PMID 25356808.
  2. ↑ Clemmons DR, Van Wyk JJ, Ridgway EC, Kliman B, Kjellberg RN, Underwood LE (1979). "Evaluation of acromegaly by radioimmunoassay of somatomedin-C". N Engl J Med. 301 (21): 1138–42. doi:10.1056/NEJM197911223012102. PMID 492275.
  3. ↑ Clemmons DR (2006). "Clinical utility of measurements of insulin-like growth factor 1". Nat Clin Pract Endocrinol Metab. 2 (8): 436–46. doi:10.1038/ncpendmet0244. PMID 16932333.
  4. ↑ Carmichael JD, Bonert VS, Mirocha JM, Melmed S (2009). "The utility of oral glucose tolerance testing for diagnosis and assessment of treatment outcomes in 166 patients with acromegaly". J Clin Endocrinol Metab. 94 (2): 523–7. doi:10.1210/jc.2008-1371. PMID 19033371.
  5. ↑ Melmed S (2006). "Medical progress: Acromegaly". N Engl J Med. 355 (24): 2558–73. doi:10.1056/NEJMra062453. PMID 17167139.


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