LACK OF ISLET AMYLOID POLYPEPTIDE AMYLIN-IMMUNOREACTIVITY IN URINE COLLECTED FROM HEALTHY-VOLUNTEERS AFTER INGESTION OF A CARBOHYDRATE-RICHMEAL

Islet amyloid polypeptide (IAPP), or amylin, is synthesized by beta ce lls in the islets of Langerhans of the pancreas. Plasma IAPP levels ar e highly elevated in patients with advanced renal failure. To investig ate the involvement of the kidney in the clearance of IAPP, the respon se of plasma and urinary IAPP to a carbohydrate-rich meal was investig ated in 14 healthy volunteers. Although plasma IAPP levels increased s everalfold after the meal, no IAPP-immunoreactivity was detected in th e urine samples up to 4 hours after the meal. This might be due to the fact that urinary IAPP levels are under the detection limit of the as say or, assuming the presence of IAPP in the primary urine, immunoreac tive IAPP molecules may be processed by renal mechanisms in such a way that they are no longer recognized by the antibodies used in the radi oimmunoassay. Processed IAPP molecules may be reabsorbed in the proxim al tubules of the kidney and/or excreted.