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Insulin-like Growth Factor-1 Test

Last updated Oct. 11, 2015


What are the other Names for this Test? (Equivalent Terms)

  • Insulin-like Growth Factor-1 Test
  • Somatomedin-C Test

What is Insulin-like Growth Factor-1 Test? (Background Information)

  • IGF-1 (Insulin-like Growth Factor-1) is a protein hormone that is essential for normal development of the body. IGF-1 is related to a hormone called Growth Hormone (GH)
  • Growth hormone is a protein that is secreted by pituitary gland present at the base of the brain. The GH, produced by the pituitary, stimulates the production of IGF-1
  • IGF-1 is produced by the liver and skeletal muscle. The function of IGF-1 is to promote the growth of muscle and bony tissue
  • There are a variety of clinical conditions, by which, the growth hormone and Insulin-like Growth Factor-1 may be increased or decreased
  • Decreased levels of both GH and IGF-1 result in retardation of body growth. The abnormal increase in growth hormone and IGF-1 may result in the abnormal and pathological growth of bones and increase in skeletal muscle mass
  • The abnormal growth resulting from increased growth hormone and IGF-1 is called, gigantism in children and, acromegaly in adults

What are the Clinical Indications for performing the Insulin-like Growth Factor-1 Test?

The clinical indications of performing IGF-1 are as follows:

  • Growth retardation in children
  • Delay in sexual development during puberty
  • In adults, IGF-1 testing is indicated when there is:
    • Increased fatigue
    • Decrease in exercise tolerance
    • Abnormal lipid profile
    • Frequent fractures, resulting from decreased bone density

The above signs and symptoms are due to a decrease in IGF-1 levels in human body. An increase in the circulation of IGF-1 can result in the following signs and symptoms.

In children this may include:

  • They easily tire on mild exercising
  • Increased joint pain with occasional swelling
  • Large head with enlarged tongue
  • Organomegaly (increased size of internal body organs such as liver, kidneys, and heart)
  • Thickened skin
  • Menstrual irregularities in pubertal adolescence

In adults, the signs and symptoms of an increased IGF-1 level could include:

  • Sudden increase in size of the skull (which may be apparent due to frequent changes in sizes of hat/helmet/headgear used)
  • Enlargement of the nose
  • Prominent jaw
  • Increase in the size of the foot (resulting in changes in shoe size)

How is the Specimen Collected for Insulin-like Growth Factor-1 Test?

Sample required: Blood

Process: The blood sample is procured through a needle, inserted into a superficial vein of the body (usually arm).

Preparation required: No special preparation is required prior to testing.

What is the Significance of the Insulin-like Growth Factor-1 Test Result?

A decrease in IGF-1 level:

  • In children, it may mean a decrease in pituitary function resulting in growth retardation
  • In adults, it may also be due to a decrease in pituitary function resulting in the symptoms (mentioned above)

An increased level of IGF-1:

  • In both adults and children may indicate the presence of a growth hormone producing tumor, in the pituitary.

Usually prompt diagnosis and early surgical intervention, with removal of the pituitary tumor, may result in IGF-1 levels coming back to normal, resulting in no further abnormal growth. 

A decreased IGF-1 level can also be caused due to:

  • Pituitary trauma
  • Abnormal inflammation of pituitary gland
  • Infections involving pituitary gland
  • Presence of high estrogen levels in the body, due to a variety of causes
  • Chronic liver disease
  • Nutritional deficiencies
  • Chronic renal failure

It is pertinent to note that an increase in IGF-1 level is physiologically normal during pubertal growth and also during pregnancy. During puberty and pregnancy, the increased levels of IGF-1 are usually temporary. The levels fall down to baseline physiological levels, after the pubertal phase or at the end of pregnancy.

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful information:

Please check back for periodic updates to our ‘physician approved content’.

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

What are some Useful Resources for Additional Information?

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References and Information Sources used for the Article:

http://labtestsonline.org/understanding/analytes/igf1/tab/test (accessed on 08/10/2013)

http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/35099 (accessed on 08/10/2013)

http://kidshealth.org/parent/system/medical/somatomedin_test.html (accessed on 08/10/2013)

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Aug. 19, 2013
Last updated: Oct. 11, 2015