Growth Assays

Growth Assays
 
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Growth hormone tests are used to help identify excess or diminished growth hormone (GH) production and provide information about the severity of a person’s condition. They are part of the diagnostic work-up required to find a cause for abnormal hormone production.1

Growth Assay Menu

Growth hormone (GH), IGF-I, and IGFBP-3 results are essential when diagnosing and treating growth disorders. The Siemens GH assay is very specific and sensitive and requires only a small sample volume. Siemens IGF-I and IGFBP-3 assays have established sex-and age-based reference intervals that are crucial in assessing the patient’s growth condition.

Our 2000/XPi IGF-I assay is now standardized to the WHO 1st International Standards for IGF-I.

 Atellica® SolutionIMMULITE® Systems
Growth Hormone             √*                  √
IGF-I             √*                  √
IGFBP-3             √*                  √

 

*Under development. Not commercially available. Future availability cannot be guaranteed

The products featured here may not be commercially available in all countries. Due to regulatory restrictions, their future availability cannot be guaranteed. Please contact your local Siemens Healthineers representative for further details.

Growth Hormones

Growth hormone (GH) is secreted from the pituitary gland. Measurement of GH is primarily of interest in the diagnosis and treatment of various forms of inappropriate growth hormone secretion.

Too much growth hormone (hypersecretion) can cause abnormal growth patterns called acromegaly in adults and gigantism in children. Too little growth hormone (hyposecretion) can cause a slow or flat rate of growth in children, and changes in muscle mass, cholesterol levels, and bone strength in adults.2 Clinical disorders of hyposecretion include dwarfism and unattained growth potential.3

IGF-I

In the diagnosis of growth disorders, measurements of IGF-I are a useful indicator of growth hormone secretion. A normal plasma or serum IGF-I concentration is strong evidence against GH deficiency. A low IGF-I value implies GH deficiency and requires additional testing to determine whether GH secretion is subnormal. Measurement of IGF-I is also useful in assessing change of nutritional status.3
An IGF-I test is often ordered along with GH. IGF-I mirrors GH excesses and deficiencies, but its level is stable throughout the day, making it a useful indicator of average GH levels.1

IGFBP-3

IGFBP-3 is used as an aid in the evaluation of growth disorders. It is growth hormone (GH) dependent and therefore useful in the evaluation of GH secretion. IGFBP-3 is the main carrier of IGF-I in the body. Blood levels of both these proteins are controlled by GH. IGFBP-3 also helps extend the life of GH in the blood and helps control its effects on body tissues.
Levels of IGFBP-3 are highest during childhood and puberty, and then decrease during adulthood. Levels may also be affected by sexual maturation and nutritional status.4

Growth Disorders

Growth disorders affect thousands of people each year. A person may be diagnosed as a child or as an adult. There are different types of growth disorders, many caused by imbalances in different types of hormones.5

Growth Hormone Deficiency

Growth hormone deficiency means the pituitary gland does not make enough growth hormone. Most of the time, the cause of growth hormone deficiency is unknown. It may be present at birth or develop as a result of an injury or medical condition. Severe brain injury may also cause growth hormone deficiency. Slow growth may first be noticed in infancy and continue through childhood. Although uncommon, growth hormone deficiency may also be diagnosed in adults. Possible causes include tumors involving the pituitary gland or hypothalamus, or brain radiation treatments for cancer.6

Excessive Growth

 

Gigantism–Excessive action of IGF-I while epiphyseal growth plates are open causes gigantism, which occurs very rarely7. Children and adolescents with gigantism stand > 2 standard deviations above the mean height for their gender and age.

 

Acromegaly–Also caused by hypersecretion of IGF-I, acromegaly is the most common disorder of GH excess8. In contrast to gigantism, it occurs in adolescence and adults after their epiphyseal growth plates have fused. The name acromegaly comes from the Greek words for “extremities”(acro) and “great”(megaly), because one of the most common symptoms of this condition is abnormal growth of the hands and feet.

The symptoms of acromegaly can vary and develop gradually over time; therefore, a diagnosis of this condition may be difficult. Early detection is a goal in the management of acromegaly because the pathologic effects of increased growth hormone (GH) production are progressive.9 IGF-I provides the most sensitive lab test for the diagnosis of acromegaly.10


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1http://labtestsonline.org/understanding/analytes/growth-hormones/tab/test

2http://www.nlm.nih.gov/medlineplus/ency/article/003706.htm

3Siemens Instructions for Use

4http://kidshealth.org/parent/system/medical/test_igfbp3.html

5http://www.hormone.org/Growth/overview.cfm

6http://www.ncbi.nlm.nih.gov/pubmedhealth/OMH0002159/

7Kuhnel, W. Growth Diagnostics: Clinical Relevance of GH, IGF-I and IGFBP-3. Los Angeles (CA), Diagnostics Products Corporation (now Siemens Healthcare Diagnostics), Technical Report ZB223-B, 2004.

8Ferry, RJ. Giantism and Acromegaly. eMedicine Specialties (Internet): 2010 July. http://emedicine.medscape.com/article/925446-overview

9www.acromegaly.org

10http://en.wikipedia.org/wiki/IGF1

The products/features (mentioned herein) are not commercially available in all countries. Due to regulatory reasons their future availability cannot be guaranteed. Please contact your local Siemens Healthineers organization for further details.