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Insulin-like Growth Factor-1 (IGF-1) With Z Score
Results of the insulin-like growth factor-1 assay are to be used in conjunction with other clinical and laboratory data to assist the clinician in the assessment of growth disorders.
Considerable differences exist between the currently available assays with respect to the results of IGF-1 measurements.
Immunochemiluminometric assay (ICMA)
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-I 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. Reference intervals were developed through a multicenter study with samples from 12 cohorts from the USA, Canada, and Europe.13 A total of 15,014 subjects were tested (6697 males and 8317 females), ranging in ages from 0 to 94 years. Results are reported in mass units with reference intervals reflecting the central 95% interval (2.5 to 97.5 percentiles). Z scores, which reflect the number of standard deviations a given result is above or below the age-adjusted mean, are reported along with the IGF-1 concentration.
0.3 mL (Note: This volume does not allow for repeat testing.)
Red-top tube or gel barrier tube
Separate serum from cells. Transfer separated serum to a plastic transport tube. Please include the patient's age on the test request form.
Age and gender must be supplied for Z score to be calculated.
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.
|Order Code||Order Code Name||Order Loinc||Result Code||Result Code Name||UofM||Result LOINC|
|010540||IGF-1 with Z-Score||010369||Insulin-Like Growth Factor I||ng/mL||2484-4|
|010540||IGF-1 with Z-Score||010541||IGF-1, Z Score||S.D.||73561-3|