Calcium Phosphate Product Is Associated with Subclinical Carotid Atherosclerosis in Type 2 Diabetes

Impact of Calcium Phosphate Product on Acute Kidney Injury and Mortality: A Retrospective Cohort Study

PURPOSE

This study aims to assess the association between admission-corrected serum calcium phosphate (CaPO4) levels and the risks of in-hospital acute kidney injury (AKI) and mortality, hypothesizing a dose-dependent relationship between serum CaPO4 concentrations and the likelihood of developing AKI.

METHODS

This large retrospective cohort study analyzed hospitalized adult patients who had serum calcium, phosphate, and albumin levels measured within 24 hours of admission between January 2014 and December 2018. Piecewise regression was employed to identify the optimal CaPO4 cutoff values for predicting in-hospital AKI and mortality. Subsequently, the odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the risks of in-hospital AKI and mortality associated with these cutoff values.

RESULTS

A total of 2,116 patients were included in the study. The incidence rates of AKI for patients with CaPO4 levels ≤27 and >27 mg2/dL2 were 9.6% and 10.9%, respectively. The bilinear association pattern revealed the lowest risk of AKI at a CaPO4 level of 27 mg2/dL2. Piecewise regression analysis showed that each 1 mg2/dL2 increase in CaPO4 level above the 27 mg2/dL2 cutoff was associated with increased risks of in-hospital AKI and mortality, with OR of 1.048 (95% CI: 1.030-1.065) and 1.048 (95% CI: 1.032-1.065), respectively.

CONCLUSION

Our findings indicate a critical relationship between elevated serum CaPO4 levels and increased risks of in-hospital AKI and mortality, with a notable cutoff at CaPO4 >27 mg2/dL2.

Fibroblast growth factor 23 and calcium-phosphate metabolism in relation to cardiovascular risk factors in patients with type 1 diabetes

BACKGROUND

Cardiovascular disease (CVD) is the major cause of mortality in type 1 diabetes (T1D). The objective of this study is to evaluate fibroblast growth factor 23 (FGF23) and calcium-phosphate metabolism in relation to cardiovascular risk factors in adults with and without T1D.

METHODS

A case-control study was conducted using data from patients with T1D and age- and sex matched controls without T1D from the Lifelines Cohort Study.

RESULTS

We included 302 adults in the T1D group and 302 adults in the control group. Median age was 42 years. Median glycosylated hemoglobin (HbA1c) in the T1D group was 7.8%. FGF23 of all patients with T1D was not significantly different from controls. Females with T1D had significantly higher FGF23 than males with T1D (83.3 vs 69.3 U/mL, p = 0.002), this was not observed in controls. Serum phosphate, calcium, and alkaline phosphatase were higher and parathyroid hormone was lower in patients with T1D, compared to controls (all p < .001), all within normal range. In the T1D group, FGF23 was positively correlated with serum phosphate (p < .001), alkaline phosphatase (p = .01), and calcium (p = .030), these correlations were not observed in controls. Median FGF23 was significantly higher in current smokers than in nonsmokers with T1D (84.9 vs 73.5 U/mL, p < .05).

CONCLUSIONS

Serum calcium, phosphate, and alkaline phosphatase were higher in patients with T1D than in controls and were positively correlated to FGF23 in patients with T1D. Current smokers with T1D had higher FGF23 than nonsmokers with T1D. These findings may contribute to the increased risk of CVD in patients with T1D.

Co-relation Between Calcium-Phosphorus Product and Hypertension in End-Stage Renal Disease Patients

Objective

In our study, we evaluated the relation between calcium-phosphorus (Ca-P) product and various measurements of pre and post-dialysis blood pressure (BP) in hemodialysis (HD) patients.

Methods

This is a prospective, observational, cross-sectional study in which patients undergoing maintenance HD for > six months were enrolled through non-probability consecutive sampling during a six-month period from October 2020 to March 2021. Linear regression analysis was done to study the effect of the Ca-P product for each parameter of BP and regression coefficients were acquired.

Results

There was a total of 111 patients in our study, of which 59 (53.2%) were male. The mean age was 50.1± 14.4. The most common comorbid was hypertension (98.2%). The mean HD vintage of patients was 5.7 ± 5.8 years. On linear regression analysis, the Ca-P product was strongly correlated with pre-HD diastolic BP (DBP) (0.7) and post-HD mean arterial pressure (MAP) (0.7) while a moderate correlation was present with pre (0.59) and post (0.64) HD systolic BP (SBP), post-HD diastolic BP (0.68), and pre-HD MAP (0.68). On the other hand, the Ca-P product was not correlated with pre and post-HD pulse pressure (0.06 and 0.1, respectively). When the independent effect of serum calcium (Ca), phosphorus (P), and parathyroid hormone on BP was studied, P had a significant correlation with pre and post-HD SBP, DBP, and MAP.

Conclusion

Our study demonstrates a significant association of the Ca-P product and an independent high P level with pre and post-dialysis SBP, DBP, and MAP while no association was found with pulse pressure.

Serum levels of C-terminal FGF23 (cFGF23) are associated with 1-year-mortality in patients undergoing transcatheter aortic valve replacement (TAVR)

INTRODUCTION

Serum levels of FGF23 have been associated with adverse outcomes in cardiovascular diseases in patients with and without impaired renal function. Hence, this study aimed to explore the prognostic relevance of intact FGF23 (iFGF23) and its derivate C-terminal FGF23 (cFGF23) in patients undergoing transcatheter aortic valve replacement (TAVR) with regard to renal function.

METHODS

A total of 274 patients undergoing transfemoral TAVR were enrolled in this study. Blood samples were obtained preinterventionally and analyzed for iFGF23 and cFGF23 by means of enzyme linked immunosorbent assay (ELISA). Follow-up was obtained for 12 months.

RESULTS

Serum levels of cFGF23 and iFGF23 both correlated positively with serum creatinine and inversely with estimated glomerular filtration rate (eGFR). Cox regression analysis revealed a significant association of cFGF23 with 1-year-mortality in patients with eGFR ≥45ml/min/1.73m², but not in patients with an eGFR <45ml/min/1.73m². A cut-off was calculated for cFGF23 (6.82 pmol/l) and patients with eGFR ≥45ml/min/1.73m² were retrospectively divided into two groups (above/below cut-off). Patients above the cut-off had a significantly worse 1-year-mortality than patients below the cut-off (33.3% vs. 19.6%; OR 2.05 (95%CI 1.03-4.07), p= 0.038). The association of cFGF23 with 1-year-mortality in patients with eGFR ≥45ml/min/1.73m² remained statistically significant even after correction for possible confounders in a multivariate Cox regression analysis.

CONCLUSION

cFGF23 could be an individual risk factor for mortality in patients undergoing TAVR with an eGFR ≥45ml/min/1.73m².

Diabetes, Diabetic Complications, and Phosphate Toxicity: A Scoping Review

This article presents a scoping review and synthesis of research findings investigating the toxic cellular accumulation of dysregulated inorganic phosphate-phosphate toxicity-as a pathophysiological determinant of diabetes and diabetic complications. Phosphorus, an essential micronutrient, is closely linked to the cellular metabolism of glucose for energy production, and serum inorganic phosphate is often transported into cells along with glucose during insulin therapy. Mitochondrial dysfunction and apoptosis, endoplasmic reticulum stress, neuronal degeneration, and pancreatic cancer are associated with dysregulated levels of phosphate in diabetes. Ectopic calcification involving deposition of calcium-phosphate crystals is prevalent throughout diabetic complications, including vascular calcification, nephropathy, retinopathy, and bone disorders. A low-glycemic, low-phosphate dietary intervention is proposed for further investigations in the treatment and prevention of diabetes and related diabetic pathologies.

Circulating IGF-1 Independently Predicts Blood Pressure in Children With Higher Calcium-Phosphorus Product Levels

OBJECTIVE

To study the association between insulin-like growth factor 1 (IGF-1) and blood pressure in children, in particular, the potential interaction with the serum calcium-phosphorus product (Ca*P).

METHODS

A longitudinal study included 521 children (age 8.8 ± 0.1) from northeastern Spain, of whom 158 were followed-up after 5 years. IGF-1, insulin-like growth factor-binding protein 3 (IGFBP-3), and serum calcium and phosphorus were measured at baseline. Anthropometric (body-mass index [BMI] and waist) and cardiometabolic variables (systolic [SBP] and diastolic blood pressure), pulse pressure, insulin, homeostatic model assessment of insulin resistance [HOMA-IR], high-density lipoprotein [HDL]-cholesterol, and triglycerides) were assessed at baseline and at the end of follow-up. Statistical analysis included Pearson correlations followed by multivariable linear regression analyses.

RESULTS

Baseline IGF-1 and IGF-1/IGFBP-3 molar ratio positively correlated with baseline and follow-up BMI, waist, SBP, pulse pressure, insulin, HOMA-IR and triglycerides (r 0.138-0.603; all P < 0.05). The associations with SBP were stronger with increasing Ca*P (r 0.261-0.625 for IGF-1; and r 0.174-0.583 for IGF-1/IGFBP-3). After adjusting for confounding variables, baseline IGF-1 and IGF-1/IGFBP-3 remained independently associated with both baseline and follow-up SBP in children in the highest Ca*P tertile (β = 0.245-0.381; P < 0.01; model R2 = 0.246-0.566).

CONCLUSIONS

Our results suggest that IGF-1 in childhood is an independent predictor of SBP in apparently healthy children, especially in those with high Ca*P levels.

Lack of Awareness of Dietary Sources of Phosphorus Is a Clinical Concern

Hyperphosphatemia is a serious complication in patients with chronic kidney disease (CKD), and is associated with more rapid progression as well as higher risk of mortality, and higher rate of cardiovascular disease accidents. CKD patients are usually advised to adopt a low phosphate diet in addition to phosphate-lowering medications, if necessary. However, there is a lack of awareness of the dietary sources of phosphate, especially hidden phosphate intake from phosphate additives in processed foods and carbonated beverages. Appropriate nutritional education could be an effective solution in reducing phosphate toxicity without introducing an additional pill burden or malnutrition.

Phosphate and Cardiovascular Disease beyond Chronic Kidney Disease and Vascular Calcification

Phosphate is essential for life but its accumulation can be detrimental. In end-stage renal disease, widespread vascular calcification occurs as a result of chronic phosphate load. The accumulation of phosphate is likely to occur long before the rise in serum phosphate above the normal range since several observational studies in both general population and early-stage CKD patients have identified the relationship between high-normal serum phosphate and adverse cardiovascular outcomes. Consumption of food high in phosphate increases both fasting and postprandial serum phosphate and habitual intake of high phosphate diet is associated with aging, cardiac hypertrophy, endothelial dysfunction, and subclinical atherosclerosis. The decline in renal function and dietary phosphate load can increase circulating fibroblast growth factor-23 (FGF-23) which may have a direct impact on cardiomyocytes. Increased FGF-23 levels in both CKD and general populations are associated with left ventricular hypertrophy, congestive heart failure, atrial fibrillation, and mortality. Increased extracellular phosphate directly affects endothelial cells causing cell apoptosis and vascular smooth muscle cells (VSMCs) causing transformation to osteogenic phenotype. Excess of calcium and phosphate in the circulation can promote the formation of protein-mineral complex called calciprotein particles (CPPs). In CKD, these CPPs contain less calcification inhibitors, induce inflammation, and promote VSMC calcification.