Is extrapancreatic tumor hypoglycemia associated with elevated levels of insulin-like growth factor II?
We have tried to answer the still controversial question of whether or not extrapancreatic tumor hypoglycemia is associated with elevated levels of insulin-like growth factor II (IGF II), keeping in mind that controversial results may be due to methodological differences. Serum levels of IGF II were determined by a rat liver membrane radioreceptor assay and by RIA. Serum samples were gel filtered at acidic pH, and some sera were also tested after acid-ethanol extraction as an alternative method for dissociating and separating IGF from the IGF carrier protein. Additionally, the radioreceptor assay was performed with a labeled partially purified IGF preparation [nonsuppressible insulin-like activity soluble in acid-ethanol (NSILA-s "70")] that was used by a group reporting elevated NSILA-s levels in about 40% of their patients with tumor hypoglycemia. Mean serum levels of receptor-reactive IGF II and immunoreactive IGF II (+/- SD) were 436 +/- 169 and 540 +/- 256 ng/ml in 22 patients with tumor hypoglycemia, as compared with 578 +/- 155 and 647 +/- 217 ng/ml in 28 normal adults. This pattern of slightly, but not significantly lower mean IGF II values in tumor hypoglycemia was unchanged when a less pure IGF preparation (NSILA-s 70) was used as a tracer or when the sera were extracted with acid-ethanol. Thus, hypoglycemia resulting from extrapancreatic tumors is not likely to be associated with increased receptorreactive or immunoreactive IGF II levels.
D000293:Adolescent; D000368:Aged; D000818:Animals; D005260:Female; D006801:Humans; D007003:Hypoglycemia / Q000097:blood* / Q000209:etiology; D007328:Insulin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications*; D011863:Radioimmunoassay; D011869:Radioligand Assay; D051381:Rats; D013002:Somatomedins / Q000097:blood*
D007328:Insulin; D013002:Somatomedins