Abstract Body (Do not enter title and authors here): Introduction: Serum calcium, phosphate, and their interaction have been linked to vascular calcification. While high calcium-phosphate ratio (Ca/P) has been associated with adverse cardiovascular outcomes especially in chronic kidney disease (CKD), its relationship with blood pressure in non-CKD remains unclear. This study aims to assess the association between Ca/P and blood pressure in individuals without CKD.
Methods: A retrospective cross-sectional analysis was conducted using data from the 2017–2020 NHANES. Mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) were calculated from 3 consecutive blood pressure measurements. Ca/P was calculated by dividing serum calcium by serum phosphate (mg/dL) and categorized into quartiles. Estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI formula, with non-CKD defined as eGFR ≥ 60 mL/min/1.73 m². Associations of serum calcium, phosphate, and Ca/P with SBP and DBP were assessed using multiple linear regression models, adjusting for demographics, comorbidities, laboratory values, average sodium and alcohol intake, and socioeconomic status.
Result: Among the 4,621 adults included, mean age±SD was 51±17 years and 91.6% was non-CKD. The mean SBP and DBP were 124±19 and 75±11mmHg, respectively. The mean serum calcium and phosphate were 9.3±0.4 and 3.6±0.5 mg/dL, and the median [IQR] Ca/P was 2.6 [2.4–2.9]. In the fully adjusted models, serum Ca/P and calcium were positively associated with mean SBP and DBP while serum phosphate showed an inverse association (all p<0.05). When Ca/P was categorized into quartiles, Q3 and Q4 were graded associated with higher SBP (aβ_SBP-Q3 2.31 (0.97-3.65) p<0.01, aβ_SBP-Q4 2.79 (1.39-4.19) p<0.01) and DBP (aβ_DBP-Q3 1.35 (0.51-2.20) p<0.01, aβ_DBP-Q4 1.71 (0.82-2.59) p<0.01). In subgroup analysis of non-CKD, Ca/P in Q3 and Q4 showed stronger associations with both higher SBP (aβ_{non-CKD/SBP-Q3} 2.64 (1.31-3.67) p<0.01, aβ_{non-CKD/SBP-Q4} 3.29 (1.89-4.69) p<0.01) and DBP (aβ_{non-CKD/DBP-Q3} 1.42 (0.55-2.28) p<0.01, aβ_{non-CKD/DBP-Q4} 1.80 (0.90-2.70) p<0.01).
Conclusion: Our study demonstrated that higher Ca/P is associated with elevated blood pressure, even in individuals without CKD. This hilights the need for further investigation into the interaction between serum calcium and phosphate in the non-CKD populations.