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Beaumont Laboratory

Insulin Like Growth Factor 1

Somatomedin-C, Sm-C, IGF-1, Antrim #19581, EPIC: LAB5819, SOFT: IGF1

Specimen Collection Criteria

Collect: One Gold-top SST tube.

Send specimen to the Laboratory for processing immediately after collection. 

Physician Office/Drawsite Specimen Preparation

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged collection tube immediately. (Minimum Serum: 0.5 mL)

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8°C or 36-46°F). (Minimum Serum: 0.5 mL)

Rejection Criteria

  • Specimens not collected and processed as indicated.

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers® with Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers® without Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 1 year

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Special Testing Laboratory.

Performed

Monday - Friday.
Results available within 2 business days.

Reference Range

Pediatric Reference Ranges (Central 95% Range)

Age (Years) Male (ng/mL) Female (ng/mL)
0-3 <15-129  18-172
4-6 22-208  35-232
 7-9 40-255 57-277
10-11 69-316 118-448
 12-13 143-506 170-527
14-15 177-507 191-496
 16-18 173-414 190-429

Adult Reference Ranges

Age (Years) Central 95% Range (ng/mL)
19-21 117-323
22-24 99-289
25-29 84-259
30-34 71-234
35-39 63-223
40-44 58-219
45-49 53-215
50-54 48-209
55-59 45-210
60-64 43-220
65-69 40-225
70-79 35-216
80-90 31-208

Tanner Stage Reference (Central 95% Range ng/mL)

Tanner Stage Male Female
1 63-271 71-394
2 114-411 122-508
3 166-510 164-545
4 170-456 174-480
5 161-384 169-400

 






Test Methodology

Chemiluminescent Immunoassay.

Interpretation

Insulin like growth factor (IGF-1) is regulated by human growth hormone (GH) and nutritional intake. Much of the GH dependent, growth promoting activity in serum is due to IGF-1. The liver is the major source of IGF-1 in blood. The anabolic and growth promoting effects mediated by the IGFs include cell proliferation and protein synthesis. Plasma IGF-1 concentrations are relatively stable making them a reliable indicator of GH output. GH levels vary considerably and often require provocative testing to interpret.

Consistently low IGF-1 levels are seen in children with GH deficiency (hypopituitarism) and rise with GH injections. Generally, normal IGF-1 levels in a short child is strong evidence against the diagnosis of GH deficiency, particularly when the patient is 5-6 years old, a time at which abnormally low values can be discriminated from normal. Serum levels may be low in GH-deficient children who have a craniopharyngioma. A normal level suggests that GH deficiency is not present, however a low value in a growth-retarded child is not diagnostic of hypopituitarism.

Undernutrition is associated with low IGF-1 levels in children.

Elevated serum IGF-1 concentrations are seen in patients with acromegaly and in children with gigantism due to excess of pituitary GH. Elevated IGF-1 serum values in pubertal patients should be interpreted carefully because levels are normally increased at this time and may be as much as 4-5 times adult concentration. IGF-1 levels are also elevated during pregnancy.

Clinical Utility

Aids in evaluation of growth disorders. Decreased IGF-1 levels are also associated with malnutrition.

CPT Code

84305.

Test Codes

Antrim #19581, EPIC: LAB5819, SOFT: IGF1

Last Updated

04/03/2018

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This directory currently reflects information only for specimens collected and/or processed at the Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.