Levels of glucose-regulatory hormones in patients with non-islet cell tumor hypoglycemia: including a review of the literature

Non-islet cell tumor hypoglycemia (NICTH) is one of the causes of spontaneous hypoglycemia. The pathogenesis of NICTH is thought to be an excessive production by tumors of big insulin-like growth factor (IGF)-II. This study investigated the levels of glucose-regulatory hormones in patients with NICTH with high serum levels of big IGF-II (big IGF-II group) and compared these with profiles of patients with spontaneous hypoglycemia with normal IGF-II (normal IGF-II group). Circulating IRI, CPR, ACTH, cortisol, GH, and IGF-I levels measured during hypoglycemic episodes were examined retrospectively in 37 patients with big IGF-II producing NICTH and 6 hypoglycemic patients with normal IGF-II. The hormone profile data of 15 patients with NICTH from published case reports were reviewed and included in the analyses. Mean plasma glucose levels (36 vs. 29 mg/dL), serum IRI (0.53 vs. 0.37 mu IU/mL), CPR (0.15 vs. 0.20 ng/mL), IGF-I SDS (-3.55 vs. -3.18 SD) and ACTH levels (27.3 vs. 33.8 pg/mL) were not significantly different between the big and normal IGF-II groups. However, mean serum GH (0.85 vs. 9.62 ng/mL) and plasma cortisol levels (16.2 vs. 34.5 mu g/dL) were significantly lower in the big IGF-II group than in the normal IGF-II group (both p<0.05). In conclusion, although the magnitude of the decrease in insulin and IGF-I levels did not differ between spontaneous hypoglycemic patients caused by other etiologies, patients with NICTH tended to have low basal GH levels during hypoglycemic episodes. These differences in hormone profile may be helpful for selecting patients who require analysis of IGF-II.