Serum Calcium Is Associated With Peripheral and Central Blood Pressure in Different Samples

Objective: Calcium homeostasis plays a crucial role in both contractility and relaxation mechanisms, determining the vasoconstriction and vasodilation of blood vessels. Some studies have reported a positive correlation between serum calcium and blood pressure (BP) levels, hypertension, metabolic syndrome, and type 2 diabetes, while others have not. Given these conflicting findings, we investigated the relationship between serum calcium and BP in three distinct samples. Our objective was to confirm the existence of a positive correlation between calcium levels and BP and to assess whether this relationship extends to central BP. Design and method: Serum calcium levels were measured in a restricted sample of patients referred to our ESH Excellence Center in Verona (n=56) with a suspicion of secondary hypertension, as well as in two large population-based studies from Sweden, the Malmö Preventive Project (MPP, n= 17,843) and from United Kingdom, the UK Biobank (UKB, n= 330,000). Central BP was estimated by tonometry performed with SphygmoCor Xcel. Results: In the Verona sample, the patients, predominantly receiving antihypertensive therapy based on calcium antagonists, serum calcium correlated with central systolic BP (r=0.37; p<0.01), and this association persisted even after adjusting for age, sex, and BMI. In the MPP, baseline serum calcium was associated with both systolic (beta 0.60, 95% CI 0.30-0.89; p<0.001) and diastolic BP (beta 0.44, 95% CI 0.26-0.62; p<0.001) after adjustment for age, sex, BMI, and antihypertensive therapy. Similarly, in the UKB, the association between both systolic (beta 1.79, 95% CI 1.74-1.85; p<10^15) and diastolic BP (beta 0.98, 95% CI 0.95-1.02; p<10 ^15) and serum calcium was confirmed after the same adjustments. Conclusions: In different samples, serum calcium consistently associates with increased BP. Further studies are warranted to elucidate whether this association is influenced by hormones regulating this electrolyte and/or by dietary calcium intake.