ECTOPIC INSULIN AND OCCAM'S RAZOR:* REAPPRAISAL OF THE RIDDLE OF TUMOUR HYPOGLYCAEMIA

Publisher Website
Google Scholar
Abstract
The concept of ectopic insulin production is challenged on the basis of a review of 120 cases from the literature on extrapancreatic tumors associated with hypoglycemia in which insulin or insulin-like activity were measured. No case met 2 or more of 5 criteria of ectopic hormone production. The evidence indicates that hypoglycemia of extrapancreatic tumors cannot be attributed to insulin. In those rare cases in which plasma insulin was reported as high, pancreatic .beta.-cells could not be excluded as the insulin source. Many of the dubious cases had carcinoid histology. The review also points out a close association between some spindle-cell tumors and carcinoid tumors which may be relevant to discussion on the disputed origin of some mesothelial tumors. Nonsuppressible insulin-like activity (NSILA) consists of a number of factors mimicking insulin activity which compete with insulin or proinsulin for membrane receptors and may crossreact in bioassay, immunoassays, and receptor assays. The question of whether 1 or several of these substances may be responsible for extrapancreatic hypoglycemia remains to be elucidated.