Onor ICO, Duchane RM, Payne CJ, et al. - This study was undertaken to investigate the differences in serum calcium levels between hypertensive crises patients and 1:1 random matched controls (age-, sex-, race-, diabetes, and body mass index-matched). A single-center, retrospective, chart review, case-control study including patients with hypertensive crises (case group) and patients without hypertensive crises (control group). In comparison with a random matched control group, no significant difference was observed in serum calcium levels in patients with hypertensive crises. There is a need for larger observational or experimental studies to assess the effect of calcium on blood pressure in hypertensive crises.