Endocrine Abstracts

Serum gastrin (G) levels >1000 pg usually raise the suspicion for a neuroendocrine tumor (NET) secreting G. Rarely, such elevated G levels are seen in pts with pernicious anemia (PA) which most commonly is associated with autoimmune gastritis (AG) (1). AG can occur concomitantly with other autoimmune d/o incl. lymphocytic colitis (LC) (2). G stimulates enterochromaffin-like cells which increase histamine (H) secretion. H excess can cause diarrhea (D) as can bacterial overgrowth (BO) or LC.

A 57 yo WF presented with D, sporadic epigastric pain, and bloating. She also had a h/o interstitial cystitis and took pentosan, cetirizine, (pantoprazole in past). She had no h/o ulcers, renal impairment or carcinoid syndrome. PE was unremarkable. Serum G was 1846 pg. EGD revealed gastritis, a pH of 7 with low stomach acid. Bx of the antrum, body of the stomach, and CLO urease testing r/o H. pylori infection. Pathology: chronic gastritis without H. pylori. Serum G and plasma CgA were suggestive of a gastrinoma or NET (table). PA was unlikely b/o nl B12 (748 pg), methylmalonic acid, homocysteine, Hb and MCV.

CT abdomen/pelvis were noncontributory. Pancreatic protocol MRI with arterial, venous, and delayed phase imaging did not reveal a pancreatic lesion.

Random colon bx performed to assess for LC was compatible with LC which may explain her diarrhea, although we also considered excessive H from elevated G, BO, and pentoasan polysulfate which can cause D and be misleading in this setting, pointing to the dx of gastrinoma. She could not stop pentosan but started a PPI and rifaximin for 10 days which decreased bloating and D. Serum G levels decreased but remained elevated (686 pg on prednisone 20 mg and a PPI).

This case illustrates that D may be associated with very high serum G levels in the setting of chronic gastritis (possible BO), LC, and interstitial cystitis (pentosan use), without clear evidence for a gastrinoma or NET. If no h/o ulcers or liver metastases is present in such cases, watchful observation rather than an extensive/invasive and costly search for a NET may be justified.

1. Lewin KJ et al. Gut 1976;17:551

2. Pardi DS, et al. Lymphocytic colitis... Am J Gastroenterol 2002; 97: 2829

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.