Measurement of human IGF-II using Sephacryl extraction: a rapid and reliable assay method

• Published in: Annals of clinical biochemistry Vol. 33 ( Pt 3); p. 201
• Main Authors: Mason, B H, Tatnell, M A, Holdaway, I M
• Format: Journal Article
• Language: English
• Published: England 01.05.1996
• Subjects: Acrylic Resins; Adult; Aged; Chromatography, Gel; Dextrans; Female; Gels; Humans; Hypoglycemia - blood; Insulin-Like Growth Factor Binding Protein 3 - blood; Insulin-Like Growth Factor I - isolation & purification; Insulin-Like Growth Factor II - isolation & purification; Male; Middle Aged; Reproducibility of Results; Time Factors
• ISSN: 0004-5632
• DOI: 10.1177/000456329603300305

Measurement of insulin-like growth factor II (IGF-II) in human serum is complicated by the presence of IGF binding proteins and usually involves cumbersome extraction procedures followed by radioimmunoassay. We have utilized an extraction process developed for measuring insulin-like growth factor II in ovine serum using Sephacryl HR100, and have applied this to the extraction of human samples followed by radioimmunoassay for human IGF-II. The assay yielded 98% recovery of unlabelled IGF-II, parallelism between dilutions of eluate and the standard curve, complete removal of binding proteins and near-complete removal of IGF-I, and intra- and interassay coefficients of variation of 5% and 9%, respectively. The normal range for serum IGF-II in women was 490-1056 micrograms/L, and IGF-II levels were positively correlated with serum concentrations of insulin-like growth factor binding protein-3 (IGFBP-3) but not with IGF-I levels. Mean serum concentrations of IGF-II were reduced below normal in a number of hypopituitary patients and children with short stature and IGF-II concentrations in these subjects correlated positively with IGF-I and IGFBP-3. In acromegalic patients IGF-II levels were usually normal and were negatively correlated with IGF-I concentrations. From our experience with the above results the present assay appears particularly suitable for clinical measurements and research projects where high sample throughput is required.