Insulin-like Growth Factor 2 (IGF-2)

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Turnaround Time: 9 - 13 days
CPT Code:


Test Type: 0.5 mL Serum, frozen
Stability Time:



Room temperature

1 day


3 days


200 days


Stable x3

Reference Range:


• Prepubertal: 258−882 ng/mL; mean: 570 ng/mL

• Pubertal: 273−892 ng/mL; mean: 583 ng/mL

• Adults: 333−967 ng/mL; mean: 650 ng/mL


An adjunct to IGF-I in the clinical evaluation of growth hormone-related disorders.

Plasma specimens produce falsely decreased results.

Insulin-like growth factor II (IGF-II) is a 7.5 kilodalton, 67 amino acid peptide which is thought to mediate some of the actions of growth hormone (GH). IGF-II peptide consists of the A, C, and B chains, and is structurally homologous to IGF-I and proinsulin. IGF-II is secreted by the liver and other tissue and is postulated to have mitogenic and metabolic actions at or near the sites of synthesis; this has been termed the paracrine role of IGF-II. IGF-II also appears in the peripheral circulation, where it circulates primarily in a high molecular weight tertiary complex with IGF-binding protein-3 (IGFBP-3) and acid-labile subunit. A smaller proportion of IGF-II may circulate in association with other IGF-binding proteins. The proportion of unbound IGF-II in the circulation has been estimated at >5%. Plasma levels of IGF-II are dependent upon adequate levels of GH and other factors, including adequate nutrition.

The actions of IGF-II are mediated by binding to specific cell surface receptors. The function of the type II IGF receptor is not completely defined. IGF-II binds with lower affinity to the IGF-I type receptors and the insulin receptors. These latter receptors may mediate the mitogenic and metabolic actions of IGF-II. Although its specific physiologic role has not been defined, it has been postulated that the interplay of IGF-I and IGF-II with the different cell surface receptors and circulating binding proteins modulates tissue growth.

Normal postnatal plasma IGF-II levels are assumed to be at maximum levels, since administration of GH does not result in increased IGF-II levels (unlike IGF-I levels, which increase). Postnatal plasma IGF-II levels show a moderate age-related increase throughout childhood and puberty, and there is no significant variability during the day. IGF-II levels decrease in GH deficiency and in malnutrition. IGF-II levels may also decrease in acromegaly and during exogenous administration of IGF-I.

Blum WF, Ranke MB, Bierich JR. A specific radioimmunoassay for insulin-like growth factor II: The interference of IGF binding proteins can be blocked by excess IGF-I. Acta Endocrinol (Copenh). 1988 Jul; 118(3):374-380. PubMed 2455951

Gluckman PD, Ambler GR. What is the function of circulating insulin-like growth factor-2 in postnatal life? Mol Cell Endocrinol. 1993 Mar; 92(1):C1-C3 (review). PubMed 8472860

Lee PD, Rosenfeld RG. Clinical utility of insulin-like growth factor assays. Pediatrician. 1987; 14(3):154-161. PubMed 3331010

Rechler MM. Insulin-like growth factor binding proteins. Vitam Horm. 1993; 47:1-114 (review). PubMed 7680510

Collection Details:

Collection Instructions:

Red-top tube or gel-barrier tube.

Transfer the serum into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen specimens, please submit frozen specimens for each test requested.