Clinical Validation of ELISA Assays for Insulin-Like Growth Factor-II (IGF-II)

Abstract

Background: Insulin-like growth factor-II (IGF-II) is known to be dysregulated in malnutrition and in non-islet cell tumour hypoglycaemia (NICTH). Its measurement may be used diagnostically in the latter condition but little information is available on its utility as a nutritional marker. The aims of this study were to clinically validate two ELISAs for measurement of IGF-II in these conditions and to provide further information relevant to their use in nutritional contexts.

Methods: IGF-II concentrations were measured by extraction and non-extraction ELISA and RIA in 20 malnourished patients referred for nutrition support. IGF-II concentrations were also measured by both ELISAs in 10 subjects with clinical features of NICTH.

Results: Baseline IGF-II measured by both ELISAs correlated with body weight in patients referred for parenteral nutrition (PN) (P < 0.05). Following commencement of PN, IGF-II concentrations climbed from baseline reaching statistical significance at days 5 and 7 of PN (P < 0.05). In specimens from subjects considered to have NICTH, IGF-II results from both ELISAs were positively biased compared to those measured by RIA. In comparison to RIA, the non-extraction ELISA yielded two false positive results and the extraction ELISA one false positive and one false negative result.

Conclusions: IGF-II may have a place in monitoring of nutrition support and merits further study of its utility as a nutritional marker. Whilst the ELISAs investigated can sensitively detect IGF-II and are valid for the measurement of IGF-II in nutritional contexts they are unlikely to replace RIA for the purpose of investigating NICTH.




J Endocrinol Metab. 2012;2(2):72-81
doi: https://doi.org/10.4021/jem82w