Acromegaly laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
Overview
[edit | edit source]An elevated concentration of serum growth hormone (GH) and insulin-like growth factor 1(IGF-1) levels is diagnostic of acromegaly.
Laboratory Findings
[edit | edit source]- 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]
- Elevated Insulin Growth Factor 1 (IGF-1) level:[1][2]
References
[edit | edit source]- ↑ 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.
- ↑ 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.
- ↑ 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.
- ↑ 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.
- ↑ Melmed S (2006). "Medical progress: Acromegaly". N Engl J Med. 355 (24): 2558–73. doi:10.1056/NEJMra062453. PMID 17167139.
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