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|Test Update Information||Effective June 6, 2011, the Growth Hormone assay is now standardized to the Recombinant Second International Standard (IS) 98/574.
Growth hormone results read approximately 25% lower than with the previous standards (1st IS 80/505). Reference ranges have also been modified according to the assay manufacturer.
|Performed by||China Basin Chemistry|
|In House Availability||Sunday or Monday (day shift)|
|Method||Chemiluminescent Immunoassay (Siemens Immulite 2000)|
|Patient Preparation||Random Growth Hormone collection should be performed on fasting patients who have rested for at least 30 minutes prior to collection.|
|Container type||Gold top|
|Amount to Collect||2 mL blood|
|Preferred volume||1 mL serum|
|Min. Volume||0.2 mL serum|
|Processing notes||Freeze serum at -20C.|
Reference range was adopted from Siemens Immulite 2000 vendor performed studies and verified in-house by running adult donor samples (excluding autologous donors) on 20 male and 20 female samples.
Pediatric reference ranges are not available for this immunoassay platform.
For children, order Growth Hormone, Ultrasensitive (test code PGHB)
|Synonyms||GH; HGH; Human growth hormone; Somatotropin|
|Turn around times||1-8 days|
|Additional information||This assay is performed in-house and is suitable for use in adult patients to assess general endocrine function.
Because of wide fluctuations in normal levels, normal ranges are difficult to define and measuring random GH values is not usually diagnostically helpful.
Screening tests for GH deficiency include measurements 1 hour after sleep or after 20 min of vigorous exercise, but definitive testing requires provocative testing. Increased levels are expected with insulin-induced hypoglycemia, arginine infusion, or the administration of L-dopa or clonidine.
Well defined, normative values for stimulation testing are not available for this assay or other widely used growth hormone assays.
Historically, peak increases of < 7 µg/L in provocative testing have been considered as suggestive of deficiency and some authorities have also considered peak values < 10 micrograms/L to be supportive of the diagnosis in children with clinical criteria for GHD.
Glucose suppression testing: In a disorder suggesting excess GH secretion, draw blood before and during a glucose tolerance test to test for the ability of glucose administration to suppress GH levels. A nadir GH concentration of less than 1 microgram/L after oral administration of glucose has been the historical standard of a normal response, however, a lower nadir GH cut point at 0.4 microgram/L has been recommended to increase sensitivity of detecting modest GH hypersecretion when using contemporary GH assays (American Association of Clinical Endocrinologists medical guidelines for clinical practice for the diagnosis and treatment of acromegaly--2011 update. Katznelson L, Atkinson JL, Cook DM, Ezzat SZ, Hamrahian AH, Miller KK; American Association of Clinical Endocrinologists. Endocr Pract. 2011 Jul-Aug;17 Suppl 4:1-44).
This Siemens Immulite 2000 assay is standardized relative to the 2nd IS 98/574 reference preparation.
Consensus guidelines for the diagnosis and treatment of growth hormone (GH) deficiency in childhood and adolescence: summary statement of the GH Research Society. GH Research Society. J Clin Endocrinol Metab. 2000 Nov;85(11):3990-3
Consensus Statement on the Standardization and Evaluation of Growth Hormone and Insulin-like Growth Factor Assays. Clinical Chemistry 2011 57:4 555-559
Consensus guidelines for the diagnosis and treatment of adults with GH deficiency II: a statement of the GH Research Society in association with the European Society for Pediatric Endocrinology, Lawson Wilkins Society, European Society of Endocrinology, Japan Endocrine Society, and Endocrine Society of Australia. European Journal of Endocrinology (2000) 157 695-700.
|Last Updated||12/3/2012 3:33:32 PM|
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