Growth Hormone

CPT: 83003 (per specimen)
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Test Details

Synonyms

  • Human Growth Hormone (hGH)
  • Somatotropic Hormone (STH)

Use

Pituitary function test useful in the diagnosis of hypothalamic disorder, hypopituitarism, acromegaly, and ectopic growth hormone production by neoplasm

Limitations

A single fasting growth hormone (GH) level is of limited value. Secretion of GH is episodic and pulsatile. GH has a half-life of 20 to 25 minutes. Testing for growth hormone deficiency or excess is best done as part of a dynamic test involving specific stimuli (see the online Endocrine Appendices: Growth Hormone Stimulation and Growth Hormone Suppression). Insulin-like growth factor-1 can also be useful in assessing growth hormone status.

As in the case of any diagnostic procedure, results must be interpreted in conjunction with the patient's clinical presentation and other information available to the physician.

Methodology

Immunochemiluminometric assay (ICMA)

Reference Interval

0.0−10.0 ng/mL

Additional Information

Human growth hormone (hGH) is a polypeptide hormone secreted from the acidophil cells of the anterior pituitary gland. Secretion is episodic and is associated with exercise, the onset of deep sleep or postprandially in response to falling glucose levels. Synthesis and release are under the control of hypothalamic releasing peptides and inhibitory peptides such as somatostatin. More recently, a gastric peptide, ghrelin, has been shown to also stimulate HGH secretion. The mediator of many hGH actions in the periphery, insulin-like growth-factor I (IGF-I) exerts an inhibitory effect through negative feedback mechanisms.1 hGH in circulation consists of several molecular isoforms, with 22,000 Dalton hGH being the most abundant, followed by a 20,000 Dalton hGH variant produced by alternative splicing. Approximately 50% of circulating hGH is bound to a high affinity binding protein.2 hGH is physiologically important in two main areas. Firstly, it has an integral role in skeletal growth which is well demonstrated in either excess or deficiency in childhood. The action of hGH in part is mediated through IGF-I as well as promoting protein synthesis and the uptake of amino acids into cells. Secondly, hGH influences intermediary metabolism by stimulating lipolysis and is antagonistic to the insulin-mediated uptake of glucose.3 hGH secretion is stimulated by hypoglycemia and suppressed by hyperglycemia.

In childhood, symptoms of hGH deficiency are retarded growth and dwarfism. Etiology is often unknown and an absolute or relative deficiency usually becomes apparent at about two years of age. Diagnosis can be confirmed by demonstrating low serum hGH which does not respond to stimulation tests. hGH deficiency is a major cause of severe short stature and diagnosis at an early stage is essential for successful therapy.4 Hyposecretion in adults usually becomes apparent during the laboratory investigation of hypopituitarism.5,6

Hypersecretion, commonly due to adenoma of the acidophil cells, is characterized by two conditions depending on whether it becomes apparent before or after fusion of the bony epiphyses. In childhood, excess hGH is characterized by gigantism. Heights of eight feet may be achieved and may also be associated with hypogonadism. In adults, acromegaly results, a condition characterized by progressive thickening of bone and soft tissue. Diagnosis is usually confirmed by dynamic function testing, which demonstrates a raised serum hGH level that does not fall in response to an oral glucose load.7 In conditions where there are nutritional disturbances, such as anorexia, starvation, renal failure, and hepatic cirrhosis, increased basal hGH levels may be found.

Recombinant hGH is available for treatment of hGH deficiency in both children and adults.4-6 hGH excess is treated by surgery, irradiation therapy, or somatostatin analogues.8,9 More recently, pegvisomant, a hGH receptor antagonist, which shares structural homology to hGH and competes with hGH for binding to the hGH receptor, has been developed.10

The IDS iSYS hGH assay conforms to the recommendations outlined in the recently published consensus statement on the standardization and evaluation of growth hormone assays.11 The assay is calibrated to the WHO International Standard for Somatropin from NIBSC, code 98/574.12 The assay is 100% specific for the 22 kDalton form of hGH and has no cross-reactivity with pegvisomant.13

Specimen Requirements

Specimen

Serum

Volume

0.8 mL

Minimum Volume

0.3 mL (Note: This volume does not allow for repeat testing.)

Container

Red-top tube or gel-barrier tube

Patient Preparation

Random growth hormone sampling should be performed on fasting patients who have rested for at least 30 minutes prior to collection. Growth hormone stimulation and suppression protocols are described in the online Endocrine Appendices: Growth Hormone Stimulation and Growth Hormone Suppression.

Collection

If a red-top tube is used, transfer separated serum to a plastic transport tube. Label tube with time of collection and patient's name.

Storage Instructions

Refrigerate

Stability Requirements

Temperature

Period

Room temperature

7 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Gross hemolysis; lipemia; plasma specimen

Clinical Information

Special Instructions

This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.

Footnotes

1. Giustina A, Veldhuis JD. Pathophysiology of the neuroregulation of growth hormone secretion in experimental animals and the human. Endocr Rev. 1998 Dec; 19(6):717-797. 2260461
2. Baumann G. Growth hormone heterogeneity: Genes, isohormones, variants, and binding proteins. Endocr Rev. 1991 Nov; 12(4):424-449. 1760996
3. Møller N, Jørgensen JO. Effects of growth hormone on glucose, lipid, and protein metabolism in human subjects. Endocr Rev. 2009 Apr; 30(2):152-177. 19240267
4. Cohen P, Rogol AD, Deal CL, et al. Consensus statement on the diagnosis and treatment of children with idiopathic short stature: A summary of the Growth Hormone Research Society, the Lawson Wilkins Pediatric Endocrine Society, and the European Society for Paediatric Endocrinology Workshop. J Clin Endocrinol Metab. 2008 Nov; 93(11):4210-4217. 18782877
5. Molitch ME, Clemmons DR, Malozowski S, Merriam GR, Vance ML; Endocrine Society. Evaluation and treatment of adult growth hormone deficiency: An Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011 Jun; 96(6):1587-1609. 21602453
6. Cook DM, Yuen KC, Biller BM, Kemp SF, Vance ML; American Association of Clinical Endocrinologists. American Association of Clinical Endocrinologists medical guidelines for clinical practice for growth hormone use in growth hormone-deficient adults and transition patients−2009 update. Endocr Pract. 2009 Sep-Oct; 15(Suppl 2):1-29. 20228036
7. Katznelson L, Atkinson JL, Cook DM, Ezzat SZ, Hamrahian AH, Miller KK. American Association of Clinical Endocrinologists medical guidelines for clinical practice for the diagnosis and treatment of acromegaly−2011 update. Endocr Pract. 2011 Jul-Aug; 17(Suppl 4):1-44. 21846616
8. Clemmons DR. Clinical laboratory indices in the treatment of acromegaly. Clin Chim Acta. 2011 Feb 20; 412(5-6):403-409. 21075098
9. Melmed S, Colao A, Barkan A, et al. Guidelines for acromegaly management: An update. J Clin Endocrinol Metab. 2009 May; 94(5):1509-1517. 19208732
10. Biermasz NR, Romijn JA, Pereira AM, Roelfsema F. Current pharmacotherapy for acromegaly: A review. Expert Opin Pharmacother. 2005 Nov; 6(14):2393-2405. 16259571
11. Clemmons DR. Consensus statement on the standardization and evaluation of growth hormone and insulin-like growth factor assays. Clin Chem. 2011 Apr; 57(4):555-559. 21285256
12. Human Growth Hormone on the IDS iSYS, package insert Date, V, Immunodiagnostic Systems Inc. (IDS Inc.). Fountain Hills, Ariz.
13. Manolopoulou J, Alami Y, Petersenn S, et al. Automated 22-kD growth hormone-specific assay without interference from Pegvisomant. Clin Chem. 2012 Oct; 58(10):1446-1456. 22908135

References

Donaldson DL, Pan F, Hollowell JG, et al. Reliability of stimulated and spontaneous growth hormone (GH) levels for identifying the child with low GH secretion. J Clin Endocrinol Metab. 1991 Mar; 72(3):647-652. 1671784
Ilondo MM, Vanderschueren-Lodeweyckx M, De Meyts P, Eggermont E. Serum growth hormone levels measured by radioimmunoassay and radioreceptor assay: A useful diagnostic tool in children with growth disorders? J Clin Endocrinol Metab. 1990 May; 70(5):1445-1451. 2186059
Rose SR, Ross JL, Uriarte M, Barnes KM, Cassorla FG, Cutler GB Jr. The advantage of measuring stimulated as compared with spontaneous growth hormone levels in the diagnosis of growth hormone deficiency. N Engl J Med. 1988 Jul 28; 319(4):201-207. 3393172
Rosenfield RG. Disorders of growth hormone and insulin-like growth factor secretion and action. In: Sperling MA, ed. Pediatric Endocrinology. Philadelphia, Pa: WB Saunders Co; 1996:117-169.
Wass JAH, Besser GM. Tests of pituitary function. In: DeGroot LJ, Besser GM, Burger HG, et al, eds.Endocrinology. 3rd ed. Philadelphia, Pa: WB Saunders Co; 1994:487-496.

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
004275 Growth Hormone, Serum 2963-7 004275 Growth Hormone, Serum ng/mL 2963-7

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