Unique Features

  • Fully compliant with Consensus Guidelines (Clemmons 2010)
  • Calibrated against the WHO IS 02/254 (Bidlingmaier 2013)
  • Extensive global reference range study
  • Calibrated against the WHO IS 02/254 (Bidlingmaier 2013)
  • Reference range SD calculation availability
  • > 4200 children and adolescent samples in reference range study
  • Tanner stages for 854 samples
  • Use of two paired monoclonal antibodies and rigorous quality control testing (in-house)
  • No interference from:
  • Insulin
  • Pro-insulin
  • IGF-II, any of the 6 IGFBPs
  • Triglyceride
  • Biotin
  • Bilirubin
  • Haemoglobin
  • Human Serum Albumin
  • Red Blood Cells
  • A complete clinical assay panel supporting growth disorder management
  • Data supporting age and gender specific values
  • Accuracy of results and no cross-reactivity
  • Fully-compliant with WHO IS 02/254 standard

The IDS-iSYS Insulin like Growth Factor-I Assay (IDS-iSYS IGF-I) is intended for the quantitative determination of IGF-I in human serum or plasma on the IDS-iSYS Multi-Discipline Automated System.

Results are to be used in conjunction with other clinical and laboratory data to assist the clinician in the assessment of growth disorders.

Insulin-like growth factor-I (IGF-I) is a polypeptide of 70 amino acids (7650 Daltons), and is one of a number of related insulin-like growth factors present in the circulation. The molecule shows approximately 50% sequence homology with proinsulin and has a number of biological activities similar to insulin.

The peptide is growth hormone (GH) dependent to a high degree, but there is growing evidence of GH-independent secretion. IGF-I has numerous growth-promoting effects, including mitogenic effects and the promotion of cartilage sulphation.

It also mediates growth promoting actions of growth hormone on skeletal and other body tissues. Almost all (>95%) of serum IGF-I circulates bound to specific IGF binding proteins, of which six classes (IGFBP’s 1-6) are now recognised. IGFBP-3 is thought to be the major binding protein of IGF-I, forming a ternary complex of 140 000 Daltons with IGF-I and an acid labile sub-unit.

The measurement of serum IGF-I is of recognised value in children with growth disorders and in the diagnosis and monitoring of acromegaly. IGF-I concentrations change with age, nutritional status, body composition and growth hormone secretion. A single basal IGF-I determination is useful in the assessment of short stature in children and in nutritional support studies of acutely ill patients.

For the diagnosis of acromegaly, a single IGF-I determination is considered more reliable than a random GH determination.

The assay is based on chemiluminescence technology. Samples are incubated with an acidic solution to dissociate IGF-I from the binding proteins. A portion of this, along with neutralisation buffer, a biotinylated anti-IGF-I monoclonal antibody and an acridinium labelled anti-IGF-I monoclonal antibody is incubated for a further period of time. Streptavidin-labelled magnetic particles are then added and following a further incubation step, the magnetic particles are “captured” using a magnet.

After a washing step and addition of trigger reagents, the light emitted by the acridinium label is directly proportional to the concentration of IGF-I in the original sample.

J Clin Endocrinol Metab. 2014 May;99(5):1712-21. doi: 10.1210/jc.2013-3059. Epub 2014 Feb 27.

J Clin Endocrinol Metab. 2014 Aug;99(8):2804-12. doi: 10.1210/jc.2013-3746. Epub 2014 May 13.

Exp Gerontol. 2014 Aug 5. pii: S0531-5565(14)00236-8. doi: 10.1016/j.exger.2014.08.001. [Epub ahead of print]