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Titolo:
Determination of free insulin-like growth factor-I in human serum: comparison of ultrafiltration and direct immunoradiometric assay
Autore:
Frystyk, J; Ivarsen, P; Stoving, RK; Dall, R; Bek, T; Hagen, C; Orskov, H;
Indirizzi:
Aarhus Kommune Hosp, Inst Expt Clin Res, DK-8000 Aarhus C, Denmark Aarhus Kommune Hosp Aarhus Denmark C Clin Res, DK-8000 Aarhus C, Denmark Aarhus Kommune Hosp, Med Dept M, DK-8000 Aarhus, Denmark Aarhus Kommune Hosp Aarhus Denmark DK-8000 pt M, DK-8000 Aarhus, Denmark Aarhus Univ Hosp, Res Lab Nephrol & Hypertens, DK-8200 Aarhus N, Denmark Aarhus Univ Hosp Aarhus Denmark N & Hypertens, DK-8200 Aarhus N, Denmark Odense Univ Hosp, Med Dept M, DK-5000 Odense, Denmark Odense Univ Hosp Odense Denmark DK-5000 Dept M, DK-5000 Odense, Denmark Aarhus Univ Hosp, Dept Ophthalmol, DK-8000 Aarhus C, Denmark Aarhus Univ Hosp Aarhus Denmark C Ophthalmol, DK-8000 Aarhus C, Denmark
Titolo Testata:
GROWTH HORMONE & IGF RESEARCH
fascicolo: 2, volume: 11, anno: 2001,
pagine: 117 - 127
SICI:
1096-6374(200104)11:2<117:DOFIGF>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
IGF-BINDING PROTEIN-1; CHRONIC-RENAL-FAILURE; HEALTHY-CHILDREN; SHORT-TERM; HORMONE; IGFBP-3; ADULTS; RADIOIMMUNOASSAY; PHARMACOKINETICS; OBESITY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
28
Recensione:
Indirizzi per estratti:
Indirizzo: Frystyk, J Aarhus Kommune Hosp, Inst Expt Clin Res, Norrebrogade 44, DK-8000 Aarhus C, Denmark Aarhus Kommune Hosp Norrebrogade 44 Aarhus Denmark C , Denmark
Citazione:
J. Frystyk et al., "Determination of free insulin-like growth factor-I in human serum: comparison of ultrafiltration and direct immunoradiometric assay", GROWTH H I, 11(2), 2001, pp. 117-127

Abstract

Two fundamentally different methods are currently used for the determination of free insulin-like growth factor-I (IGF-I): ultrafiltration by centrifugation (UF) and direct immunoradiometric assay (IRMA). The aim was to evaluate a commercial IRMA (DSL, Webster, TX, USA) and to compare it with UF Inthe IRMA it is recommended that samples be incubated for 2 h at 5 degreesC. When comparing samples (n = 8) incubated for 1(3)/(4) and 2(1)/(4) h, levels increased by 27 +/- 5% (P < 0.0001). When incubating samples at 22*C instead of 5'C, levels increased by 1 92 32% (P < 0.000 1). Addition of IGF-binding protein-1 (IGFBP-1) to normal sera (n = 6) dose-dependently decreased ultrafiltered free IGF-I only (P < 0.0007). Similarly, UF was more sensitive than IRMA to addition of IGFBP-2 (P < 0.05). In healthy subjects (n = 35) IRMA yielded 20% higher levels than UF (1.09 +/-0.09 vs 0.91 +/-0.12 mug/L; P < 0.0001). IRMA and UF yielded similar results in healthy subjects treated with IGF-I (n = 5) or growth hormone (n = 7) and in acromegalic patients (n = 6) before and after somatostatin analogue treatment. However, marked differences were observed in conditions with elevated IGFBP-1 and -2. Intype-1 diabetics (n = 23) ultrafiltered free IGF-I was more reduced than IRMA free lGF-I (38 +/-9 vs 76 +/-7% of matched controls (n = 13); P < 0.0001). In patients with chronic renal failure (n = 25), IRMA free IGF-I was identical to control levels (n = 13), whereas ultrafiltered free IGF-I was decreased by 51 +/-7% (P < 0.0001). Similarly, women with anorexia nervosa (n= 9) studied before and after weight gain showed significant changes in ultrafiltered free IGF-I only (P <less than> 0.03). In conclusion, IRMA was not very robust with respect to variations in sample incubation and this maybias results. IRMA generally yielded higher levels than UF, in accordance with the knowledge that IRMA measures free plus readily dissociable IGF-I. IRMA was less affected than UF by added IGFBP-1 and -2, and reductions in free IGF-I were better revealed by UF than IRMA. (C) 2001 Harcourt Publishers Ltd.

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Documento generato il 15/07/20 alle ore 08:32:33