Plasma gastrin measurement cannot be used to diagnose a gastrinoma in patients on either proton pump inhibitors or histamine type-2 receptor antagonists.
BACKGROUND
Patients with a gastrinoma are treated with proton pump inhibitors (PPI) and histamine type-2 receptor antagonists (H2). In order to diagnose a gastrinoma these drugs must be discontinued, but this increases the risk of gastrointestinal perforation. We aimed to determine if a gastrinoma could be diagnosed without cessation of PPI/H2 therapy.


METHODS
In all, 90 patients (controls and patients diagnosed with a gastrinoma both on and off PPI/H2 therapy) were recruited, and plasma gastrin measured.


RESULTS
Patients with a gastrinoma on PPI/H2 medication had a significantly higher fasting plasma gastrin concentration than control patients on PPI/H2 medication (298+/-33 versus 204+/-30 pmol/L, P = 0.01). However, there was substantial overlap between gastrin levels in these two groups.


CONCLUSIONS
This study confirms that a gastrinoma cannot be diagnosed on the basis of a fasting plasma gastrin assay while patients remain on PPI/H2 therapy.
Department of Endocrinology, Imperial College Faculty of Medicine, Hammersmith Hospital, London W12 ONN, UK.
W S
WS
Dhillo
C N
CN
Jayasena
C J
CJ
Lewis
N M
NM
Martin
K C N
KC
Tang
K
K
Meeran
J F
JF
Todd
D000368:Aged; D005260:Female; D015408:Gastrinoma / Q000175:diagnosis* / Q000188:drug therapy; D005755:Gastrins / Q000097:blood*; D006635:Histamine H2 Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000175:diagnosis* / Q000188:drug therapy; D054328:Proton Pump Inhibitors
D005755:Gastrins; D006635:Histamine H2 Antagonists; D054328:Proton Pump Inhibitors