Insulin-like Growth Factor 1 (IGF-1), Pediatric With Z Score

Create a Free Account to View Prices


Turnaround Time: 6 - 12 days
CPT Code:


Test Type: 0.5 mL Serum, frozen
Stability Time:

Freeze. Stable for two days at room temperature or refrigerated. Stable for two years frozen.


IGF-1 measurements can be useful when evaluating patients of gestational age1 who are suspected of being (1) growth hormone-deficient2 or (2) acromegalic.3

Plasma specimens may produce falsely elevated or decreased results. The IGF-1 reference intervals by pubertal Tanner stages reflect ranges and means based on asymmetric curves. Z scores are calculated based on the asymmetric curves with transformed data. Patient gender and date of birth must be provided in order to calculate a z score. Z scores will not be calculated for patients younger than three years or older than 18 years.

Insulin-like growth factor 1 (IGF-1) is a polypeptide hormone that can affect growth-promoting activity and glucose metabolism. IGF-1 exists in a three-subunit complex form, with IGF-1 or IGF-2 (υ-subunit), IGFBP-3 (β-subunit), and acid labile subunit (ALS) (α-subunit). Samples are acid:ethanol extracted to remove IGF-1 from the complex, resulting in a consistent IGF-1 measurement, even with variable binding protein levels. The extracted sample is then analyzed by radioimmunoassay using a highly specific antibody.4

1. Lee PA, Chernausek SD, Hokken-Koelega ACS, et al. International Small for Gestational Age Advisory Board Consensus Development Conference Statement: Management of short children born small for gestational age. April 24-Oct 1, 2011. Pediatrics. 2003; 111(6):1253-1261. PubMed 12777538

2. GH Research Society. Consensus guidelines for the diagnosis and treatment of the GH Research Society. J Clin Endocrinol Metab. 2000; 85(11):3990-3993. PubMed 11095419

3. Giustina A, Chanson P, Bronstein MD, et al. A consensus on criteria for cure of acromegaly. J Clin Endocrinol Metab. 2010; 95(7):3141-3148. PubMed 20410227

4. Alberti C, Chevenne D, Mercat I, et al. Serum concentrations of insulin-like growth factor (IGF-1) and IGF binding protein-3 (IGFBP-3), IGF-1/IGFBP-3 ratio, and markers of bone turnover: Reference values for French children and adolescents and Z-score comparability with other references. Clin Chem. 2011; 57(10):1424-1435. PubMed 21865482

Collection Details:

Collection Instructions:

Red-top tube or gel-barrier tube.

Serum must be separated from cells within 45 minutes of venipuncture. Send serum in a plastic transport tube. Transfer specimen to a plastic transport tube before freezing. To avoid delays in turnaround time when requesting multiple tests on frozen specimens, please submit separate frozen specimens for each test requested.

Freeze. Stable for two days at room temperature or refrigerated. Stable for two years frozen.