Test Details
Methodology
Immunochemiluminometric assay (ICMA)
Result Turnaround Time
2 - 4 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.
Use
The IDS-iSYS Insulin-like Growth Factor-I (IGF-I) assay is an in vitro diagnostic device intended for the quantitative determination of IGF-I in human serum or plasma on the IDS system. Results are to be used in conjunction with other clinical and laboratory data to assist the clinician in the assessment of growth disorders.
Special Instructions
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Limitations
Malnutrition will cause low somatomedin-C levels in spite of normal amounts of circulating growth hormone. The Sm-C level does not distinguish pituitary dwarfism from constitutional delay of growth and development.2
Footnotes
References
Custom Additional Information
IGF-1 is a relatively small peptide (molecular weight 7647) that is tightly bound in serum to one of several high affinity binding proteins.1 IGF-1 has approximately 50% sequence homology with proinsulin and has a number of biological activities similar to insulin. IGF-1 is a hormone that serves as the major effector of GH-stimulated somatic growth, as well as GH-independent anabolic responses in numerous tissues. IGF-1 has numerous growth-promoting effects, including mitogenic effects and the promotion of cartilage sulfation. Measurement of serum IGF-1 has been widely used in the diagnosis of disorders of GH secretion,2-6 management of disorders that lead to nutritional insufficiency, or catabolism,7-9 and monitoring both GH and IGF-1 replacement therapy. IGF-1 measurement may also have a role in the physiology of malignant disease.10,11
The IDS iSYS IGF-1 assay conforms to the recommendations outlined in the recently published consensus statement on the standardization and evaluation of IGF-1 assays.12 The assay is calibrated to the WHO recombinant reference standard 02/254 for IGF-1.13 Reference intervals for IGF-I using the IDS IGF-I were determined in a clinical routine study population from the United States.13,14 The cohort included 778,173 males and 710,752 females, aged from 0 to 90 years, who were representative of the overall United States population in terms of gender, race and ethnicity. Reference intervals were adjusted for age and sex using a modified Hoffman approach.15
Specimen Requirements
Specimen
Serum
Volume
0.5 mL
Minimum Volume
0.2 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or gel-barrier tube
Collection Instructions
Separate serum from cells. Transfer separated serum to a plastic transport tube. Please include the patient's age on the test request form.
Stability Requirements
Temperature | Period |
---|---|
Room temperature | 3 days |
Refrigerated | 7 days |
Frozen | 90 days |
Freeze/thaw cycles | Stable x3 |
Reference Range
See table.1
Age (y) | Male (ng/mL) | Female (ng/mL) | Age (y) | Male (ng/mL) | Female (ng/mL) |
---|---|---|---|---|---|
<1 | 18−79 | 14−106 | 18 | 145−506 | 117−430 |
1 | 20−108 | 23−136 | 19 | 122−435 | 113−408 |
2 | 24−135 | 30−163 | 20 | 116−410 | 108−384 |
3 | 28−148 | 34−192 | 21 to 25 | 109−353 | 101−347 |
4 | 32−165 | 38−217 | 26 to 30 | 101−307 | 91−308 |
5 | 37−196 | 46−243 | 31 to 35 | 95−290 | 84−281 |
6 | 43−229 | 56−268 | 36 to 40 | 90−278 | 79−259 |
7 | 50−243 | 64−288 | 41 to 45 | 84–270 | 74−239 |
8 | 59−275 | 74−337 | 46 to 50 | 81−263 | 70−225 |
9 | 67−315 | 81−405 | 51 to 55 | 74-−255 | 65−216 |
10 | 75−366 | 85−526 | 56 to 60 | 68−247 | 60−207 |
11 | 82−423 | 91−610 | 61 to 65 | 64−240 | 57−202 |
12 | 87−519 | 110−656 | 66 to 70 | 59−230 | 52−196 |
13 | 101–620 | 150–678 | 71 to 75 | 53−222 | 48−191 |
14 | 123−701 | 174−656 | 76 to 80 | 45−207 | 42−185 |
15 | 161−760 | 156−586 | 81 to 85 | 40−194 | 39−177 |
16 | 171−748 | 140−517 | 86 to 90 | 33−176 | 34−169 |
17 | 161−635 | 130−471 | >90 | Not established | Not established |
Storage Instructions
Refrigerate.
Causes for Rejection
Plasma specimen
LOINC® Map
Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
---|---|---|---|---|---|---|
010363 | IGF-1 | 2484-4 | 010369 | Insulin-Like Growth Factor I | ng/mL | 2484-4 |
Order Code | 010363 | |||||
Order Code Name | IGF-1 | |||||
Order Loinc | 2484-4 | |||||
Result Code | 010369 | |||||
Result Code Name | Insulin-Like Growth Factor I | |||||
UofM | ng/mL | |||||
Result LOINC | 2484-4 |