Diagnosis of pancreatic tumour or a ganglioneuroma which secretes vasoactive intestinal peptide (VIP).
Administration of VIP to animals causes hyperglycaemia, inhibition of gastric acid, secretion of pancreatic bicarbonate and of small intestinal juice, and a lowering of systemic blood pressure with skin flush. These features are seen in patients with a tumour of this type which is secreting VIP.
With the patient at rest after an overnight fast, take blood (10 mL) into a syringe.
Transfer the blood (10 mL) to a heparin tube (do not exceed 20 U/mL blood) containing Trasylol (aprotinin, 0.2 mL, 2000 KIU). Mix by inversion. Place on ice and transfer to the laboratory. Separate the plasma in a refrigerated centrifuge. Freeze the plasma at -20C within 15 min of venepuncture. Send plasma (5 mL) to the SAS laboratory. Ensure the sample remains frozen during transport. Samples with visible haemolysis will be discarded.
Adults: <30 pmol/L;
Patients with VIP-producing tumour: >80 pmol/L.
Centre offering this assay
London Imperial Charing Cross Hospital Endocrine Laboratory