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For hours, walk-ins and appointments.Insulin-like Growth Factor 1 (IGF-1), Pediatric With Z Score (Endocrine Sciences)
CPT:
84305
Expected Turnaround Time
6 - 12 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
Specimen Requirements
Specimen
Serum, frozen
Volume
0.5 mL
Minimum Volume
0.1 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection
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.
Storage Instructions
Freeze. Stable for two days at room temperature or refrigerated. Stable for two years frozen.
Causes for Rejection
Specimen not serum
Test Details
Use
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
Limitations
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.
Methodology
Blocking radioimmunoassy (RIA) after acid:alcohol extraction
Additional Information
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
Footnotes
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):1253-1261.12777538
2. GH Research Society. Consensus guidelines for the diagnosis and treatment of the GH Research Society. J Clin Endocrinol Metab. 2000; 85(11):3990-3993.11095419
3. Giustina A, Chanson P, Bronstein MD, et al. A consensus on criteria for cure of acromegaly. J Clin Endocrinol Metab. 2010; 95(7):3141-3148.20410227
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):1424-1435.21865482
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 503660 | IGF-1, Pediatric with Z-Score | 500486 | IGF-1(BL) | ng/mL | 2484-4 | |
| 503660 | IGF-1, Pediatric with Z-Score | 503668 | IGF-1 Z-Score for Tanner 1 | 73561-3 | ||
| 503660 | IGF-1, Pediatric with Z-Score | 503669 | IGF-1 Z-Score for Tanner 2 | 73561-3 | ||
| 503660 | IGF-1, Pediatric with Z-Score | 503670 | IGF-1 Z-Score for Tanner 3 | 73561-3 | ||
| 503660 | IGF-1, Pediatric with Z-Score | 503671 | IGF-1 Z-Score for Tanner 4 & 5 | 73561-3 |
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