Plasma insulin-like growth factor-II (IGF-II) and IGF-II/IGF-I ratio in a chilean case of Doege-Potter Syndrome.

Abstract

Doege-Potter syndrome is a rare clinical entity characterized by recurrent hypoglycemic events caused by non-pancreatic tumors secreting an incompletely processed high-molecular-weight form of Insulin-like Growth factor-II (IGF-II). To report IGF-II and IGF-I circulating levels in a Chilean case of Doege-Potter syndrome and control individuals, and to identify the high-molecular-weight form of IGF-II. We measured IGF-II and IGF-I plasma levels using enzyme-linked immunoassays (ELISA) in the patient and ten controls. We identified the high-molecular-weight form of IGF-II performed by Western blot. The plasma concentration of IGF-II in the patient was 868.9 ng/mL, which is only slightly > 80th percentile of controls (681,4 ± 212,8 ng/mL; mean ± standard deviation). In contrast, IGF-I plasma concentration in the patient was 17.6 ng/mL, which is notoriously lower than the corresponding levels in controls (109.1 ± 19.1 ng/mL). The IGF-II/IGF-I ratio in the patient was 49.4 (normal value < 10), which is 7.8 times higher compared to the average ratio of controls (6.3 ± 1.5). The high-molecular form of IGF-II presence in samples was confirmed through Western blot. The plasma IGF-II/IGF-I ratio better indicates the Doege-Potter syndrome's metabolic impairment than isolated measurements of circulating IGF-II or IGF-I levels.