Fig. 2

Serum magnesium levels in proton pump inhibitor (PPI) users and non-users between patients aged < 75 years and those aged ≥ 75 years. For patients aged < 75 years, PPI users, n = 26; PPI non-users, n = 106. For patients aged ≥ 75 years, PPI users, n = 47; PPI non-users, n = 85. Data were analyzed by two-tailed Mann–Whitney U-test. The boxes indicate the third quartile (Q3) at the top of the box, median, and first quartile (Q1) at the bottom. The whiskers show 5 percentiles at the bottom end and 95 percentiles at the top end. Cross symbols are considered to be outliers. IQR: interquartile range. The horizontal dotted line indicates the lower limit of reference values for serum magnesium levels, i.e., 1.8 mg/dL. Four of the 264 eligible patients were diagnosed with hypomagnesemia