Proton Pump Inhibitors versus H2 Blockers and Risk of Hypomagnesemia

Philadelphia—At many transplant centers, the use of proton pump inhibitors (PPIs) has replaced the use of H2 receptor blockers (H2B) for gastrointestinal prophylaxis, despite a lack of evidence for superior efficacy of PPIs over H2Bs. According to researchers, although PPIs are generally safe medications, their use has been associated with hypomagnesemia due to impaired gastrointestinal absorption.

Mohamad Alhosaini, MD, and colleagues hypothesized that PPIs would result in higher prevalence and severity of hypomagnesemia compared with H2Bs. The researchers reported results of a study to test the hypothesis during a poster session at Kidney Week 2014. The poster was titled Proton Pump Inhibitors Are Associated with Severe Hypomagnesemia in Renal Transplant Patients.

The researchers reviewed the medical records of all adults who received kidney transplants alone at the Loyola University Medical Center, Maywood, Illinois, between January 2010 and December 2012. Patients were excluded from the analysis if they had delayed graft function, death within 1 year of the transplant date, or use of PPI or H2B for less than 1 year.

The primary study outcomes were incidence of hypomagnesemia (mean serum magnesium of <1.8 mg/dL during the first year after transplantation), incidence of severe hypomagnesemia (serum magnesium <1.3 mg/dL on any occasion), and use of magnesium supplements.

During the study period, 187 patients received kidney transplants at the center. After application of exclusion and inclusion criteria, the study included analysis of the records of 83 patients. Mean age was 52.2 years, 59% were male, and 59% were white. All were taking calcineurin inhibitors.

Of the 87 patients in the study, 43 were treated with PPIs and 40 were treated with H2Bs. Overall, 65% had hypomagnesemia.

In the PPI group, mean serum magnesium was 1.70 compared with 1.79 in the H2B group (P=.006). Hypomagnesemia occurred in 77% of patients taking PPIs and in 60% of patients taking H2B (P=.10). Severe hypomagnesemia was more common in the PPI group than in the H2B group (21% vs 5%; P=.032).

Use of magnesium supplements was more common in the PPI group than in the H2B group (47% vs 23%; P=.022). The incidence of diabetes mellitus, serum albumin, and use of a diuretic was similar between the two groups. Both PPI and diuretic use were independent risk factors of severe hypomagnesemia on logistic regression analysis.

“The use of PPI after renal transplantation causes more severe hypomagnesemia and leads to greater use of oral magnesium supplements compared to H2B. Given the lack of confirmed superior benefit of PPI versus H2B and the potential harmful effect of hypomagnesemia, we suggest restricting prophylactic PPI use in renal transplant patients to those who are at high risk for GI bleeding,” the researchers concluded.

Source: Alhosaini M, Leehey DJ, Kavitha V. Proton pump inhibitors are associated with severe hypomagnesemia in renal transplant patients. Abstract of poster presented at Kidney Week 2014, Philadelphia, Pennsylvania, November 13, 2014.