Immunoglobulin deficiency responding to vitamin B12 in two elderly patients with megaloblastic anaemia

Effect of long-term gastric acid suppressive therapy on serum vitamin B12 levels in patients with Zollinger-Ellison syndrome

BACKGROUND AND AIMS

Long-term treatment with H(+)-K(+)-adenotriphosphatase (ATPase) inhibitors, such as omeprazole or lansoprazole, for severe gastroesophageal reflux disease is now widely used. Whether such treatment will result in vitamin B12 deficiency is controversial. We studied whether long-term treatment with omeprazole alters serum vitamin B12 levels in patients with Zollinger-Ellison syndrome.

METHODS

In 131 consecutive patients treated with either omeprazole (n = 111) or histamine H2-receptor antagonists (n = 20), serum vitamin B12 and folate levels and complete blood counts were determined after acid secretion had been controlled for at least 6 months. These studies were repeated yearly. Serum vitamin B12 and folate levels were correlated with the type of antisecretory drug and the extent of inhibition of acid secretion.

RESULTS

The mean duration of omeprazole treatment was 4.5 years, and for H2-receptor antagonists 10 years. Vitamin B12 levels, but not serum folate levels or any hematological parameter, were significantly (P = 0.03) lower in patients treated with omeprazole, especially those with omeprazole-induced sustained hyposecretion (P = 0.0014) or complete achlorhydria (P < 0.0001). In 68 patients with two determinations at least 5 years apart, vitamin B12 levels decreased significantly (30%; P = 0.001) only in patients rendered achlorhydric. The duration of omeprazole treatment was inversely correlated with vitamin B12 levels (P = 0.013), but not folate levels. Eight patients (6%) developed subnormal B12 levels during follow-up.

CONCLUSIONS

Long-term omeprazole treatment leads to significant decreases in serum vitamin B12 but not folate levels. These results suggest patients with Zollinger-Ellison syndrome treated with H(+)-K(+)-ATPase inhibitors should have serum vitamin B12 levels monitored. Furthermore, these results raise the possibility that other patients treated chronically with H(+)-K(+)-ATPase inhibitors may develop B12 deficiency.

Short term toxicity of nitrous oxide on the immune, hemopoietic, and endocrine systems in CD-1 mice

Occupational exposures to subanesthetic levels of N2O have been documented to result in suppressed proliferative cell activities. Male CD-1 mice were exposed to 0, 50, 500, and 5000 ppm of N2O for 6 hr/day, 5 days/week for 2 or 13 weeks. Tritiated-thymidine ([3H]-TdR) uptake was measured in CD-1 splenic lymphocytes cultured with and without mitogens and in a mixed lymphocyte culture (MLC). Antibody-mediated immunocompetency was determined for sheep red blood cell (SRBC)-sensitized animals by plaque forming cell (PFC) assay and serum anti-SRBC antibody (Ab) titer. Deoxyuridine suppression tests (dUrdST) were performed on bone marrow cells. There was significantly decreased splenic lymphocyte uptake of [3H]-TdR by cells cultured with mitogenic substances and in MLC following 2-week exposures to 5000 ppm. After 13-week exposures the animals' splenic lymphocytes showed increased [3H]-TdR uptake following high N2O dosing in both the mitogen-induced blastogenesis and MLC assays. Compared to control animals, the 5000 ppm exposure group had significantly depressed PFC activity and circulating anti-SRBC Ab levels following the 13-week N2O exposures, and all 13-week exposure groups demonstrated decreased liver weights and leukopenia. Bone marrow activity at these dosing levels was depressed in a dose-dependent fashion following 13-week gas exposures.