Unique Features

  • IGFBP-3 and IGF-I/IGFBP-3 Ratio Extensive global reference range study (Friedrich 2014) . Reference range SD calculation availability
  • Use of two paired monoclonal antibodies and rigorous quality control testing
  • Requires low sample volume (6 µL)
  • Tanner stages for 854 samples
  • A complete clinical assay panel supporting growth disorder management
  • Accuracy of results – measurement of correct isoform and no cross-reactivity
  • Data supporting age and gender specific values

The IDS-iSYS Insulin-like Growth Factor Binding Protein-3 (IGFBP-3) assay is intended for the quantitative determination of IGFBP-3 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. IGFBP-3 can be used in the assessment of growth disorders and as an indicator of growth hormone (GH) secretion.

The IGF system is well characterised and plays a critical role in the growth and differentiation of normal and malignant cells. The components of the IGF-I system include Growth Hormone (GH), IGF-I and II, type I and II receptors, IGF binding proteins and proteases.

Insulin-like growth factor binding proteins were first identified for their high affinity interactions with IGF-I and IGF-II. A consensus was reached on the nomenclature for IGF-binding proteins (IGFBP’s) of which there are 6 members (IGFBP-1-6).

IGFBP-3 is an abundant IGFBP species in circulation and binds 75% to 90% of circulating IGF-I in a 150kDa ternary complex consisting of IGFBP-3, IGF-I and acid-labile subunit (ALS). IGFBP-3 has a molecular weight of 28.7 kDa, comprises of 264 amino acids and acts to modulate the activity of IGF I and II and to increase their half-life.

It has been postulated that IGFBP-3 is regulated by GH and originates in the liver as low levels were observed in patients with impaired hepatic function. IGFBP-3 values are used in the investigation of growth hormone deficiency (paediatric and adult), acromegaly, hypopituitarism and to monitor rhGH therapy. GH deficient patients have subnormal IGFBP-3 levels and determination of the IGFBP-3 concentration is sufficient for the diagnosis of GH deficiency with high confidence.

The IGFBP-3 assay is based on chemiluminescence technology. Samples and calibrators are diluted in a diluent and a portion of this is incubated with a biotinylated anti-IGFBP-3 monoclonal antibody and an acridinium labelled anti-IGFBP-3 antibody for a period of time.

Streptavidin coated magnetic particles are then added and following a further incubation step, the 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 IGFBP-3 in the original sample.

J Clin Endocrinol Metab. 2014 May;99(5):1675-86. doi: 10.1210/jc.2013-3060. Epub 2014 Jan 31.

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]