Unique Features

  • Fully compliant with Consensus Guidelines (Clemmons 2010)
  • Calibrated against the WHO IS 02/254 (Bidlingmaier 2013)
  • Extensive global reference range study
  • 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 (IGF-I) assay (IDS 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.

Reference Intervals

  1. Bidlingmaier M, Friedrich N, Emeny RT, Spranger J, Wolthers OD, Roswall J, Korner A, Obermayer-Pietsch B, Hubener C, Dahlgren J, Frystyk J, Pfeiffer AF, Doering A, Bielohuby M, Wallaschofski H, Arafat AM. Reference intervals for insulin-like growth factor-1 (igf-i) from birth to senescence: results from a multicenter study using a new automated chemiluminescence IGF-I immunoassay conforming to recent international recommendations. J Clin Endocrinol Metab. 2014;99(5):1712-1721.
  2. Friedrich N, Wolthers OD, Arafat AM, Emeny RT, Spranger J, Roswall J, Kratzsch J, Grabe HJ, Hübener C, Pfeiffer AF, Döring A, Bielohuby M, Dahlgren J, Frystyk J, Wallaschofski H, Bidlingmaier M. Age- and sex-specific reference intervals across life span for insulin-like growth factor binding protein 3 (IGFBP-3) and the IGF-I to IGFBP-3 ratio measured by new automated chemiluminescence assays. J Clin Endocrinol Metab. 2014;99(5):1675-86.
  3. Emeny RT, Bidlingmaier M, Lacruz ME, Linkohr B, Peters A, Reincke M, Ladwig KH. Mind over hormones: sex differences in associations of well-being with IGF-I, IGFBP-3 and physical activity in the KORA-Age study. Exp Gerontol. 2014 Nov;59:58-64.

Clinical trials in acromegaly using the IDS-iSYS IGF-I assay

  1. Melmed S, Popovic V, Bidlingmaier M, Mercado M, van der Lely AJ, Biermasz N, Bolanowski M, Coculescu M, Schopohl J, Racz K, Glaser B, Goth M, Greenman Y, Trainer P, Mezosi E, Shimon I, Giustina A, Korbonits M, Bronstein MD, Kleinberg D, Teichman S, Gliko-Kabir I, Mamluk R, Haviv A, Strasburger C. Safety and efficacy of oral octreotide in acromegaly: results of a multicenter phase III trial. J Clin Endocrinol Metab. 2015;100:1699-1708.
  2. Dal J, Hoyer KL, Pedersen SB, Magnusson NE, Bjerring P, Frystyk J, Moller N, Jessen N, Jorgensen JO. Growth Hormone and Insulin Signaling in Acromegaly: Impact of Surgery Versus Somatostatin Analog Treatment. J Clin Endocrinol Metab. 2016;101:3716-3723.
  3. Strasburger CJ, Karavitaki N, Stormann S, Trainer PJ, Kreitschmann-Andermahr I, Droste M, Korbonits M, Feldmann B, Zopf K, Sanderson VF, Schwicker D, Gelbaum D, Haviv A, Bidlingmaier M, Biermasz NR. Patient-reported outcomes of parenteral somatostatin analogue injections in 195 patients with acromegaly. Eur J Endocrinol. 2016;174:355-362.
  4. Heinrich DA, Reinholz C, Bauer M, Tufman A, Frohner R, Schopohl J, Bidlingmaier M, Kosilek RP, Reincke M, Schneider HJ. IGF-1-based screening reveals a low prevalence of acromegaly in patients with obstructive sleep apnea. Endocrine. 2018;60:317-322.
  5. Muhammad A, Coopmans EC, Delhanty PJD, Dallenga AHG, Haitsma IK, Janssen J, van der Lely AJ, Neggers S. Efficacy and Safety of switching to Pasireotide in Acromegaly Patients controlled with Pegvisomant and Somatostatin Analogues: PAPE extension study. Eur J Endocrinol. 2018;179:269-277.
  6. Muhammad A, van der Lely AJ, Delhanty PJD, Dallenga AHG, Haitsma IK, Janssen J, Neggers S. Efficacy and Safety of Switching to Pasireotide in Patients With Acromegaly Controlled With Pegvisomant and First-Generation Somatostatin Analogues (PAPE Study). J Clin Endocrinol Metab. 2018;103:586-595.
  7. Trainer PJ, Newell-Price JDC, Ayuk J, Aylwin SJB, Rees A, Drake W, Chanson P, Brue T, Webb SM, Fajardo C, Aller J, McCormack AI, Torpy DJ, Tachas G, Atley L, Ryder D, Bidlingmaier M. A randomised, open-label, parallel group phase 2 study of antisense oligonucleotide therapy in acromegaly. Eur J Endocrinol. 2018;179:97-108.
  8. Muhammad A, Coopmans EC, Gatto F, Franck SE, Janssen J, van der Lely AJ, Hofland LJ, Neggers S. Pasireotide Responsiveness in Acromegaly Is Mainly Driven by Somatostatin Receptor Subtype 2 Expression. J Clin Endocrinol Metab. 2019;104:915-924.
  9. Coopmans EC, Schneiders JJ, El-Sayed N, Erler NS, Hofland LJ, van der Lely AJ, Petrossians P, Potorac J, Muhammad A, Neggers S. T2-signal intensity, SSTR expression, and somatostatin analogs efficacy predict response to pasireotide in acromegaly. Eur J Endocrinol. 2020;182:595-605.