Inappropriately elevated plasma insulin-like growth factor II in relation to suppressed insulin-like growth factor I in the diagnosis of non-islet cell tumour hypoglycaemia.
The diagnosis of non-islet cell tumour (hypoinsulinaemic) hypoglycamia has been complicated by contradictory biochemical evidence. Although insulin-like growth factor II (IGF-II) has been identified as the hypoglycaemic agent, plasma levels are often not elevated. In this study specific radioimmunoassay procedures for the measurement of IGF-I and IGF-II are described. Reference data on plasma IGF-II concentrations in relation to a wide range of IGF-I levels have been accumulated using plasma samples from acromegalic, hypopituitary and insulinoma (i.e. hyperinsulinaemic hypoglycaemia) patients as well as normal subjects from all age groups. The reference data indicate that a low plasma IGF-I value is normally associated with a relatively low plasma IGF-II level. Within a group of hypoinsulinaemic hypoglycaemia patients, a small number, invariably with evidence of a neoplasm, had low plasma IGF-I concentrations but apparently normal IGF-II levels. We propose that, in such cases, an apparently normal plasma IGF-II value is inappropriately high for the low plasma IGF-I level and, in association with non-ketotic hypoinsulinaemia and suppressed plasma growth hormone (GH), is diagnostic of a non-islet cell tumour as the cause of hypoglycaemia.
Department of Clinical Biochemistry and Clinical Nutrition, St. Luke's Hospital, Guildford, Surrey, UK.
J D
JD
Teale
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Marks
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007003:Hypoglycemia / Q000097:blood / Q000209:etiology*; D007223:Infant; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D007335:Insulin-Like Growth Factor II / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000097:blood / Q000150:complications / Q000175:diagnosis*; D012016:Reference Values; D013002:Somatomedins / Q000032:analysis*
D007328:Insulin; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II