As expected, we found no association between hospitalization with hypomagnesemia and current use of histamine H2 receptor antagonists (unadjusted odds ratio 2.12, 95% CI 1.17–3.86; adjusted odds ratio 1.06; 95% CI 0.54–2.06) (Table 3). This evidence concerns the gene HRH2 and familial primary hypomagnesemia.