Effect of early serum phosphate disorder on in-hospital and 28-day mortality in sepsis patients: a retrospective study based on MIMIC-IV database

BACKGROUND

This study aims to assess the influence of early serum phosphate fluctuation on the short-term prognosis of sepsis patients.

METHODS

This retrospective study used the Medical Information Mart for Intensive Care IV database to analyze serum phosphate levels in sepsis patients within 3 days of ICU admission. According to the absolute value of delta serum phosphate (the maximum value minus the minimum value of serum phosphorus measured within three days), the patients were divided into four groups, 0-1.3, 1.4-2.0, 2.1-3.1, and ≥ 3.2 mg/dl. Meanwhile, the direction of delta serum phosphate was compared. With the serum phosphate change group of 0-1.3 mg/dl as the reference group, the relationship between delta serum phosphate and in-hospital mortality and 28-day mortality was analyzed by multivariate Logistics regression analysis.

RESULTS

The study involved 1375 sepsis patients. Serum phosphate changes (0-1.3, 1.4-2.0, 2.1-3.1, and ≥ 3.2 mg/dl) correlated with in-hospital and 28-day mortality variations (p = 0.005, p = 0.008). Much higher serum phosphate fluctuation elevated in-hospital and 28-day mortality. Compared to the 0-1.3 mg/dl change group, adjusted odds ratios (OR) in other groups for in-hospital mortality were 1.25 (0.86-1.81), 1.28 (0.88-1.86), and 1.63 (1.10-2.43), and for 28-day mortality were 1.21 (0.86-1.72), 1.10 (0.77-1.57), and 1.49 (1.03-2.19). Under the trend of increasing serum phosphate, the ORs of in-hospital mortality and 28-day mortality in ≥ 3.2 mg/dl group were 2.52 and 2.01, respectively.

CONCLUSION

In conclude, the delta serum phosphate ≥ 3.2 mg/dl was associated with in-hospital mortality and 28-day mortality in patients with sepsis.

Long-term trajectories of bone metabolism parameters and bone mineral density (BMD) in obese patients treated with metabolic surgery: a real-world, retrospective study

PURPOSE

Potential negative effects of metabolic surgery on skeletal integrity remain a concern, since long-term data of different surgical approaches are poor. This study aimed to describe changes in bone metabolism in subjects with obesity undergoing both Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG).

METHODS

A single center, retrospective, observational clinical study on real-world data was performed enrolling subjects undergoing metabolic surgery.

RESULTS

123 subjects were enrolled (males 31: females 92; ages 48.2 ± 7.9 years). All patients were evaluated until 16.9 ± 8.1 months after surgery, while a small group was evaluated up to 4.5 years. All patients were treated after surgery with calcium and vitamin D integration. Both calcium and phosphate serum levels significantly increased after metabolic surgery and remained stable during follow-up. These trends did not differ between RYGB and SG (p = 0.245). Ca/P ratio decreased after surgery compared to baseline (p < 0.001) and this decrease remained among follow-up visits. While 24-h urinary calcium remained stable across all visits, 24-h urinary phosphate showed lower levels after surgery (p = 0.014), also according to surgery technique. Parathyroid hormone decreased (p < 0.001) and both vitamin D (p < 0.001) and C-terminal telopeptide of type I collagen (p = 0.001) increased after surgery.

CONCLUSION

We demonstrated that calcium and phosphorous metabolism shows slight modification even after several years since metabolic surgery, irrespective of calcium and vitamin D supplementation. This different set point is characterized by a phosphate serum levels increase, together with a persistent bone loss, suggesting that supplementation alone may not ensure the maintenance of bone health in these patients.

Association between serum phosphate and in-hospital mortality of patients with AECOPD: A retrospective analysis on eICU database

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is an important adverse event in the development of chronic obstructive pulmonary disease (COPD). Hyperphosphatemia is associated with higher mortality in patients with multiple diseases. In this study, we aimed to determine the relationship between serum phosphate and the risk of in-hospital mortality in patients with AECOPD. Methods: In the present study, patients with AECOPD were enrolled in the electronic Intensive Care Unit Collaborative Research Database (eICU-CRD), and divided into three groups according to the tertiles of serum phosphate level. The primary outcome measure was all-cause in-hospital mortality. The association between serum phosphate level and in-hospital mortality was investigated using multivariate logistic regression analysis. Moreover, subgroup analysis was performed to explore whether the relationship was consistent among different subgroups. Results: A total of 1199 AECOPD patients were included in this study. Non-survivors had higher serum phosphate levels than survivors. All patients were classified into lowest tertile, median tertile, and highest tertile, respectively. Multivariate logistic regression analysis indicated that serum phosphate was positively associated with in-hospital mortality after adjusting for confounders. Moreover, there was a significant trend across tertiles when serum phosphate level was diverted as a categorical variable. In addition, subgroup analysis demonstrated that serum phosphate was consistently associated with a higher risk of in-hospital mortality in different subgroups. Conclusion: Higher serum phosphate was positively associated with the increased in-hospital mortality in patients with AECOPD. Hyperphosphatemia may be an underlying high-risk factor for in-hospital mortality owing to AECOPD.

Association between serum phosphate levels and anemia in non-dialysis patients with chronic kidney disease: a retrospective cross-sectional study from the Fuji City CKD Network

BACKGROUND

Patients with chronic kidney disease (CKD) present high mortality and morbidity rates despite the availability of various therapies. Although CKD-mineral and bone disorder (MBD) and renal anemia are important factors in patients with CKD, only few studies have analyzed the relationship between them. Therefore, this study aimed to evaluate the relationship between CKD-MBD and anemia in patients with CKD who did not receive erythropoiesis-stimulating agent or iron therapies.

METHODS

This retrospective cross-sectional study included patients with CKD aged ≥ 20 years with estimated glomerular filtration rate (eGFR) categories G2a to G5 who were referred to the Fuji City General Hospital between April 2018 and July 2019. The exclusion criterion was ongoing treatment for CKD-MBD and/or anemia.

RESULTS

The data of 300 patients with CKD were analyzed in this study. The median age of patients was 71 (range, 56.5-79) years. The median eGFR was 34 (range, 20-48) mL/min/1.73 m2, and the mean hemoglobin (Hb) level was 12.7 g/dL (standard deviation, 2.3), which decreased as the CKD stage increased. In a multivariate linear regression analysis of anemia-related factors, including age, renal function (eGFR), nutritional status, inflammation, and iron dynamics (serum iron level, total iron-binding capacity, ferritin levels), the serum phosphate levels were significantly associated with the Hb levels (coefficient [95% confidence interval], -0.73 [-1.1, -0.35]; P < 0.001). Subgroup analysis revealed a robust association between serum phosphate levels and Hb levels in the low-ferritin (coefficient [95% confidence interval], -0.94 [-1.53, -0.35]; P = 0.002) and advanced CKD groups (coefficient [95% confidence interval], -0.89 [-1.37, -0.41]; P < 0.001).

CONCLUSIONS

We found an association between high serum phosphate levels and low Hb levels in patients with CKD not receiving treatment for anemia. These results underscore the possibility of a mechanistic overlap between CKD-MBD and anemia.

Self-Administration of Burosumab in Children and Adults with X-Linked Hypophosphataemia in Two Open-Label, Single-Arm Clinical Studies

INTRODUCTION

X-linked hypophosphataemia (XLH) is a rare, genetic renal phosphate-wasting disease, resulting from excess fibroblast growth factor 23 (FGF23) activity, which has a progressive and profound impact on patients throughout life. The monoclonal anti-FGF23 antibody, burosumab, is a subcutaneous injection indicated for the treatment of XLH in children and adults. Originally, burosumab was approved to be administered by a healthcare professional (HCP), but the option of self-administration would enable patient independence and easier access to treatment. Two open-label, single-arm clinical trials, conducted in Japan and Korea, have assessed the safety and efficacy of self-administration of burosumab in both children and adults with XLH.

METHODS

In KRN23-003 (n = 15 children aged 1-12 years) and KRN23-004 (n = 5 children aged 3-13 years, n = 4 adults aged 21-65 years), children initially received 0.8 mg/kg of burosumab every 2 weeks and adults initially received 1.0 mg/kg of burosumab every 4 weeks. Self-administration was permitted from Week 4, and patients or carers were provided with training to inject correctly.

RESULTS

In both trials, burosumab had an acceptable safety profile with mainly mild-to-moderate adverse events. Following self-administration, no patients reported serious treatment-emergent adverse events ≥ grade 3, injection-site reactions or hypersensitivity reactions related to burosumab. Serum phosphate and active vitamin D levels increased from baseline in children and adults.

CONCLUSIONS

These results indicated that the efficacy and safety of burosumab when administered either by a carer or patient are similar to that when administered by an HCP and show that self-administration is a viable option for patients with XLH.

TRIAL REGISTRATION NUMBERS

NCT03233126 and NCT04308096.

Association between admission serum phosphate and risk of acute kidney injury in critically ill patients with rhabdomyolysis: A retrospective study based on MIMIC-Ⅲ

BACKGROUND

The incidence of acute kidney injury (AKI) is high in critically ill patients with rhabdomyolysis. Limited evidence was proved of the association between serum phosphate levels at intensive care unit (ICU) admission and the subsequent risk of AKI. Our study aims to assess if serum phosphate levels at admission were independently associated with AKI risk in these patients.

METHODS

This study extracted and analyzed data from Medical Information Mart for Intensive Care-Ⅲ (MIMIC-Ⅲ, version1.4). Rhabdomyolysis was defined as a peak creatine kinase (CK) level higher than 1000 U/L. Serum phosphate was measured within the first day into the ICU and was categorized to 4 groups (<2.6, 2.6-3.4, 3.5-4.5, >4.5mg/dl). AKI was defined according to the Kidney Disease Improving Global Outcome (KDIGO) guidelines. Adjusted smoothing spline plots and multivariable logistic regressions were carried out to explode the association between serum phosphate and risk of AKI. Subgroup analyse was applied to verify the consistency of the association.

RESULTS

Three hundred and twenty-one patients (68% male) diagnosed as rhabdomyolysis were eligible for this analysis. AKI occurred in 204 (64%) patients of total. Incidence of AKI with admission serum phosphate groups<2.6, 2.6-3.4, 3.5-4.5 and>4.5mg/dl were 53%, 57%, 68% and 76%, respectively. Smoothing spline curve showed that there was a positive curve between the elevated phosphate values and increasing risk of AKI, and there was no threshold saturation effect. In multivariable logistic regression, OR was 1.2 (95%CI 1.0-1.5, P=0.035, P trend=0.041) after adjusting confounders. Subgroup analyses proved the consistency of the relationship in these patients, possibly, except in the strata of potassium.

CONCLUSION

In rhabdomyolysis patients admitted to ICU, serum phosphate levels at admission were independently associated with an increased risk of AKI. As phosphate levels rise, the risk of AKI increased.

Impact of serum phosphate on severity and functional outcomes after ischemic stroke in young adults

BACKGROUND AND AIMS

Serum phosphate is an essential nutrient that plays multiple physiological roles in cardiovascular function. The aim of this study was to investigate the association between serum phosphate and stroke severity and prognosis in ischemic stroke and transient ischemic attack (TIA) among young adults.

METHODS AND RESULTS

We retrospectively recruited patients with acute ischemic stroke and TIA aged 18-45 years. The primary outcome was 90-day poor functional outcome (modified Rankin Scale score of 2-6). The secondary outcomes included stroke severity (NIHSS ≥5 was defined as moderate to severe stroke) and poor functional outcome at hospital discharge. A total of 687 patients with a mean age of 36.8 years were enrolled. Lower serum phosphate levels were significantly associated with more severe stoke (P for trend = 0.017). Compared with the fourth quartile, the odds ratio (95% CI) of the first quartile was 1.85 (1.19-3.22) for moderate to severe stroke. After adjusting for confounders other than stroke severity, the odds ratio (95% CI) of the first quartile was 1.74 (1.06-2.86) for poor functional outcome at hospital discharge and 1.90 (1.09-3.31) at 90-day follow-up compared with the fourth quartile. However, the significant association between serum phosphate and poor functional outcomes disappeared after stroke severity was further adjusted.

CONCLUSIONS

Serum phosphate is more likely a marker of stroke severity than a contributor to poor functional outcomes after ischemic stroke and TIA in young adults. Lower serum phosphate levels were associated with more severe stroke.

Efficacy of Burosumab in Adults with X-linked Hypophosphatemia (XLH): A Post Hoc Subgroup Analysis of a Randomized Double-Blind Placebo-Controlled Phase 3 Study

The anti-fibroblast growth factor 23 monoclonal antibody burosumab corrects hypophosphatemia in adults with X-linked hypophosphatemia (XLH) and improves pain, stiffness, physical function, and fatigue. This post hoc subgroup analysis used data from the 24-week placebo-controlled period of a phase 3 study in 134 adults with XLH (ClinicalTrials.gov NCT02526160), to assess whether the benefits of burosumab are evident in 14 clinically relevant subgroups defined by baseline demographic and functional criteria, including sex, Brief Pain Inventory-short form (BPI-SF) Average And Worst Pain, region, race, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC®) Stiffness, Physical Function and Pain domains and total score, use of opioid/other pain medication, active fractures/pseudo-fractures, and 6-min walk test distance. There were no statistically significant interactions between any of the subgroups and treatment arm for any endpoint. Higher proportions of subjects achieved mean serum phosphate concentration above the lower limit of normal (the primary endpoint) with burosumab than with placebo in all subgroups. For the key secondary endpoints (WOMAC Stiffness and Physical Function; BPI-SF Worst Pain) individual subgroup categories showed improvements with burosumab relative to placebo. For additional efficacy endpoints, burosumab was favored in some subgroups but differences were not significant and confidence intervals were wide. For some endpoints the treatment effect is small at 24 weeks in all subjects. This subgroup analysis shows that burosumab was largely superior to placebo across endpoints in the 14 clinically relevant subgroup variables at 24 weeks and is likely to benefit all symptomatic adults with active XLH.

Association of hyperphosphatemia with an increased risk of sudden death in patients on hemodialysis: Ten-year outcomes of the Q-Cohort Study

BACKGROUND AND AIMS

Sudden death is one of the most common causes of death among patients on hemodialysis. Although hyperphosphatemia is a well-known risk factor for cardiovascular and all-cause deaths, the studies focusing on the relationship between serum phosphate levels and the risk of sudden death are limited. This study aimed to clarify the relationship between serum phosphate levels and the risk of sudden death in patients on hemodialysis.

METHODS

This is a multicenter, longitudinal, and observational study. A total of 3505 patients, registered in the Q-Cohort Study, who underwent maintenance hemodialysis, and were followed up for 10 years, were included. Patients were divided into quartiles on the basis of baseline serum phosphate levels: Q1 (n = 886), <4.2 mg/dL; Q2 (n = 837), 4.2-4.8 mg/dL; Q3 (n = 908), 4.9-5.6 mg/dL; and Q4 (n = 874), ≥5.7 mg/dL. Associations between baseline serum phosphate levels and sudden death were analyzed using the Cox proportional hazards model and the Fine-Gray regression model.

RESULTS

During the follow-up period, 227 patients died from sudden death. The risk for sudden death was significantly higher in the highest quartile (Q4) than in the lowest quartile (Q1) as the reference group (multivariable-adjusted hazard ratios and 95% confidence intervals: Q1, 1.00; Q2, 1.15 [0.77-1.70], Q3, 1.31 [0.89-1.93], and Q4, 1.72 [1.14-2.59]; hazard ratio for every 1-mg/dL increase in the serum phosphate level, 1.23 [1.09-1.39]; p < 0.001).

CONCLUSIONS

Hyperphosphatemia is independently associated with an elevated risk of sudden death in patients on hemodialysis.

Importance of serum phosphate in elderly patients with diabetes mellitus

BACKGROUND

Metabolic disturbances including changes in serum calcium, magnesium or phosphate (P) influence the prevalence of type 2 diabetes mellitus (DM). We assessed the importance of serum P in elderly patients with type 2 DM vs non-diabetes mellitus (non-DM) in relation to renal function.

AIM

To determine the association between serum P and serum glucose or insulin resistance in diabetic and non-diabetic patients.

METHODS

One hundred-ten subjects with a mean age of 69.02 ± 14.3 years were enrolled. Twenty-nine of the participants had type 2 DM (26.4%). The incidence of hypertension, smoking and receiving vitamin D (vitD) derivates were recorded. The participants were classified by both estimated glomerular filtration rate (eGFR) and albuminuria categories according to the Kidney Disease Improving Global Outcomes 2012 criteria.

RESULTS

We divided the patients in two groups according to the P cut-off point related to DM value. A comparison between high and low P showed that body mass index 30.2 ± 6.3 vs 28.1 ± 4.6 (P = 0.04), mean glucose 63.6 vs 50.2 (P = 0.03), uric acid 6.7 ± 1.6 vs 6.09 ± 1.7 (P = 0.05), mean intact-parathyroid hormone 68.06 vs 47.4 (P = 0.001), systolic blood pressure 147.4 ± 16.7 vs 140.2 ± 16.1 (P = 0.02), mean albuminuria 63.2 vs 50.6 (P = 0.04) and eGFR 45.6 ± 22.1 vs 55.4 ± 21.5 (P = 0.02) were significantly different. χ² tests showed a significant association between high P and DM, hypertension, receiving vitD, smoking and eGFR stage (χ² = 6.3, P = 0.01, χ² = 3.9, P = 0.03, χ² = 6.9, P = 0.009, χ² = 7.04, P = 0.01 and χ² = 7.36, P = 0.04, respectively). The adjusted model showed that older age, female gender and increased body mass index were significant predictors of type 2 DM when entering the covariates.

CONCLUSION

High serum P contributes to vascular and metabolic disturbances in elderly patients with type 2 DM and renal impairment.

Elevation of phosphate levels impairs skeletal myoblast differentiation

Hyperphosphatemic conditions such as chronic kidney disease are associated with severe muscle wasting and impaired life quality. While regeneration of muscle tissue is known to be reliant on recruitment of myogenic progenitor cells, the effects of elevated phosphate loads on this process have not been investigated in detail so far. This study aims to clarify the direct effects of hyperphosphatemic conditions on skeletal myoblast differentiation in a murine in vitro model. C2C12 murine muscle progenitor cells were supplemented with phosphate concentrations resembling moderate to severe hyperphosphatemia (1.4–2.9 mmol/l). Phosphate-induced effects were quantified by RT-PCR and immunoblotting. Immunohistochemistry was performed to count nuclear positive cells under treatment. Cell viability and metabolic activity were assessed by XTT and BrdU incorporation assays. Inorganic phosphate directly induced ERK-phosphorylation in pre-differentiated C2C12 myoblast cells. While phosphate concentrations resembling the upper normal range significantly reduced Myogenin expression (− 22.5%, p = 0.015), severe hyperphosphatemic conditions further impaired differentiation (Myogenin − 61.0%, p < 0.0001; MyoD − 51.0%; p < 0.0001). Analogue effects were found on the protein level (Myogenin − 42.0%, p = 0.004; MyoD − 25.7%, p = 0.002). ERK inhibition strongly attenuated phosphate-induced effects on Myogenin expression (p = 0.002). Metabolic activity was unaffected by the treatments. Our data point to a phosphate-induced inhibition of myoblast differentiation without effects on cell viability. Serum phosphate levels as low as the upper normal serum range significantly impaired marker gene expression in vitro. Investigation of cellular effects of hyperphosphatemia may help to better define serum cutoffs and modify existing treatment approaches of phosphate binders, especially in patients at risk of sarcopenia.

Relationship between cFGF23/Klotho ratio and phosphate levels in patients with chronic kidney disease

PURPOSE

To characterize the relationship between the cFGF23/Klotho ratio and phosphate level in patients with chronic kidney disease (CKD).

METHODS

A total of 152 patients with CKD stage 3-5 (CKD stage 3: n = 74; CKD stage 4: n = 60; CKD stage 5: n = 18) were included in the study. Thirty healthy volunteers served as controls. Intact-FGF23, cFGF23, Klotho, serum calcium, serum phosphate, and serum creatinine were measured, and estimated glomerular filtration rate (eGFR) was calculated. The Kruskal-Wallis H test was used for comparison between groups, and the Spearman test was used for correlation analysis.

RESULTS

In CKD stage 3-5, creatinine and iFGF23 levels, as well as the cFGF23/Klotho ratio, were higher (P < 0.01), phosphate levels were higher (P < 0.05), and Klotho levels were lower (P < 0.01), compared with controls. C-terminal-FGF23 levels were higher in CKD phase 4-5 (P < 0.05). In CKD stage 4-5, creatinine, iFGF23, and phosphate levels, as well as the cFGF23/Klotho ratio, were higher (P < 0.01), cFGF23 levels were higher (P < 0.05), and Klotho levels were lower (P < 0.05), compared with CKD stage 3. In CKD stage 5, creatinine and cFGF23 levels, as well as the cFGF23/Klotho ratio, were higher (P < 0.01), phosphate and iFGF23 levels were higher (P < 0.05), and Klotho levels were lower (P < 0.01), compared with CKD stage 4. Phosphate was positively correlated with the cFGF23/Klotho ratio (r = 0.235, P < 0.01).

CONCLUSIONS

EGFR reduction was associated with an increased cFGF23/Klotho ratio, and the cFGF23/Klotho ratio was positively correlated with phosphate. This suggests that the phosphate level can be controlled by modifying the cFGF23/Klotho ratio.

Low serum phosphate and magnesium levels are associated with peripheral neuropathy in patients with type 2 diabetes mellitus

AIMS

To determine the relationship of serum phosphate, serum magnesium and peripheral nerve function in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 254 patients diagnosed with T2DM were included. Peripheral nerve function was evaluated by nerve conduction study with the use of electromyography. Composite z scores of conduction velocity, latency, and amplitude were constructed, respectively. Demographic, medical and laboratory data including serum phosphate and magnesium were collected.

RESULTS

Serum phosphate and serum magnesium levels were significantly lower in patients with diabetic peripheral neuropathy (DPN) (P < 0.01). And the percentages of DPN patients were lower in high tertile of serum phosphate and serum magnesium (P < 0.05). Furthermore, composite z score of conduction velocity (CV) (P = 0.012) were positively associated with serum phosphate levels and the composite z score of amplitude (P < 0.001) and CV (P = 0.041) were positively associated with serum magnesium levels. After adjusting potential related factors (age, gender, smoking, diabetes duration, body mass index, systolic blood pressure, glycated hemoglobin, total cholesterol, estimated glomerular filtration rate), serum levels of phosphate and magnesium were still related to status of DPN in logistic regression (P < 0.05).

CONCLUSION

Lower serum phosphate and magnesium significantly correlated with parameters of nerve conduction in T2DM patients. Serum phosphate and magnesium might underlie the pathophysiologic features of DPN.

Conventional Treatment of Hypoparathyroidism

Conventional therapy of hypoparathyroidism consists of oral calcium and either activated vitamin D or vitamin D supplements at varying doses. Although adjusting dosing of calcium and/or activated vitamin D or vitamin D itself, the serum calcium should be obtained weekly or monthly depending on the clinical situation. Calcium supplementation in hypoparathyroidism usually consists of calcium carbonate because it is 40% elemental calcium by weight. However, calcium citrate (21% elemental calcium) is indicated for patients with achlorhydria and proton pump inhibitor therapy. Many clinicians prefer to uptitrate the activated form of vitamin D to reduce the amount of calcium supplementation.

HIV, TB, inflammation and other correlates of serum phosphate: A cross-sectional study

BACKGROUND

There is little information about serum phosphate levels among patients with pulmonary tuberculosis (TB) and HIV infection.

OBJECTIVE

We aimed to assess the role of TB, HIV, inflammation and other correlates on serum phosphate levels.

METHODS

A cross-sectional study was conducted among TB patients and age- and sex-matched non-TB controls. Pulmonary TB patients were categorized as sputum -negative and -positive, based on culture. Age- and sex-matched non-TB controls were randomly selected among neighbours to sputum-positive TB patients. Data on age, sex, alcohol and smoking habits were obtained. HIV status, serum phosphate, and the acute phase reactants C-reactive protein (serum CRP) and α₁-acid glycoprotein (serum AGP) were determined. Linear regression analysis was used to identify correlates of serum phosphate.

RESULTS

Of 1605 participants, 355 (22.1%) were controls and 1250 (77.9%) TB patients, of which 9.9% and 50.4% were HIV-infected. Serum phosphate was determined before start of TB treatment in 44%, and 1-14 days after start of treatment in 56%. Serum phosphate was up to 0.10 mmol/L higher 1-3 days after start of TB treatment, and lowest 4 days after treatment, after which it increased. In multivariable analysis, TB patients had 0.09 (95% CI: 0.05; 0.13) mmol/L higher serum phosphate than controls, and those with HIV had 0.05 (95% CI: 0.01; 0.08) mmol/L higher levels than those without. Smoking was also a positive correlate of serum phosphate, whereas male sex and age were negative correlates.

CONCLUSION

While HIV and TB are associated with higher serum phosphate, our data suggest that TB treatment is followed by transient reductions in serum phosphate, which may reflect hypophosphataemia in some patients.

Serum phosphorus, cardiovascular and all-cause mortality in the general population: A meta-analysis

BACKGROUND

The association between elevated serum phosphorus concentration and cardiovascular or all-cause mortality yielded conflicting results.

OBJECTIVE

To assess the association between elevated serum phosphorus concentration and cardiovascular or all-cause mortality in the general population by conducting a meta-analysis.

METHODS

We systematically searched the Pubmed and Embase databases until March 2016 for the prospective studies investigating serum phosphorus concentration and cardiovascular or all-cause mortality in the general population. We pooled risk ratio (RR) and corresponding 95% confidence intervals (CI) for the highest versus the reference category of serum concentration of phosphorus.

RESULTS

Six prospective cohort studies involving 120,269 subjects were identified. When compared the highest with the reference concentration of serum phosphorus, the pooled RR of cardiovascular mortality and all-cause mortality were 1.36 (95% CI 1.07-1.72) and 1.35 for all-cause mortality (95% CI 1.15-1.58), respectively. Stratified analyses revealed that elevated serum phosphorus significantly increased all-cause mortality risk among men (RR 1.33; 95% CI 1.11-1.60), but not in women (RR 1.09; 95% CI 0.89-1.33).

CONCLUSIONS

Elevated serum phosphorus concentration is independently associated with excessive risk of cardiovascular and all-cause mortality in the general population without chronic kidney disease. Serum phosphorus on all-cause mortality risk appears to be pronounced in men but exhibits no clear effect on women. However, gender difference of elevated serum phosphorus on mortality risk should be verified by more prospective studies.

Serum phosphate is an independent predictor of the total aortic calcification volume in non-hemodialysis patients undergoing cardiovascular surgery

BACKGROUND

A high serum phosphate level is a well-known risk factor for vascular calcification (VC) in patients on hemodialysis (HD). However, the association between the serum phosphate level and VC in non-HD patients is unclear. Our aim was to assess the impact of serum phosphate level on aortic calcification (AC) volume in non-HD patients undergoing cardiovascular surgery.

METHODS

A total of 117 patients who underwent thoracoabdominal computed tomography as a preoperative general evaluation before cardiovascular surgery were enrolled. The total AC volume was quantified using the volume-rendering method by extracting the area ≥130HU within the entire aorta. The total AC volume index (AC-VI) was estimated as the total AC volume divided by the body surface area.

RESULTS

In the 117 patients (64.7±13.1 years, 39% women), the median total AC-VI was 1.23mL/m(2). The mean estimated glomerular filtration rate (eGFR), adjusted serum calcium levels, and serum phosphate levels were 63.8±19.9mL/min/1.73m(2), 9.1±0.4mg/dL, and 3.6±0.6mg/dL, respectively. When the patients were classified into four quartiles based on their total AC-VI value, the serum phosphate level showed a positive correlation with a probability of being in the highest AC-VI quartile (R(2)=0.0146, p=0.0383) whereas the adjusted serum calcium level did not show a significant correlation (R(2)=0.0040, p=0.2615). A similar relationship between the serum phosphate level, adjusted serum calcium level, and AC-VI was confirmed when the total AC-VI was divided into the thoracic AC-VI and abdominal AC-VI. Multivariate analysis indicated that the serum phosphate level was an independent positive predictor of higher total AC-VI quartiles (β=0.8013, p=0.0160).

CONCLUSIONS

An increase in serum phosphate level was associated with an increased AC burden in non-HD patients undergoing cardiovascular surgery.

Effect of Sodium Phosphate Supplementation on Cycling Time Trial Performance and VO2 1 and 8 Days Post Loading

This study examined the effect of 6 days of sodium phosphate (SP) (50 mg·kg·FFM(-1)·day(-1)) or placebo (PL) supplementation in trained cyclists on either 100 kJ (23.9 Kcal) (~3-4 min) or 250 kJ (59.7 Kcal) (~10-12 min) time trials performances both 1 and 8 days post-supplementation. Trials were performed in a counterbalanced crossover design, with a 28-day washout period between supplementation phases. No significant differences, moderate-large ES (d) or likely (or greater) smallest worthwhile change (SWC) values were recorded for time to completion and mean power output on days 1 and 8 post-supplementation, both within and between SP and PL for either the 100 or 250 kJ (23.9 or 59.7 Kcal) trials. In the 100 kJ (23.9 Kcal) trial (only) first minute VO2 tended to be higher in SP8 than both PL8 (d = 0.60; 88/10/2 SWC) and SP1 (d = 0.47: 82/15/3 SWC), as was mean VO2 (PL8: d = 0.77; 93/6/1 SWC and SP1: d = 0.84; 90/8/3 SWC). No significant differences were found for heart rate, ratings of perceived exertion and blood lactate post-exercise within or between any trials, while serum phosphate values were not different before or after supplementation with SP or PL. In conclusion, this study showed a tendency for increased VO2 in a short duration (100 kJ/ 23.9 Kcal: ~3-4 min) cycling test on day 8 after SP supplementation, but no differences in 100 or 250 kJ (23.9 or 59.7 Kcal) time trials performances were observed. Key PointsStudies investigating the effects of sodium phosphate loading on shorter duration (<15 min) and higher intensity exercise performance are lacking, as is research on how long any ergogenic effect may last.Loading did not improve cycling time trial (~3-4 min and 10-12 min) performance either 1 or 8 days after supplementation.Future studies should investigate the effect of sodium phosphate loading on repeated sprints and simulated cycling road race performance over extended durations (>30 min), where it may be likely to have a more beneficial effect.

Serum phosphate levels reflect responses to cardiac resynchronization therapy in chronic heart failure patients

BACKGROUND

Recent studies have shown that high levels of serum phosphate are associated with adverse cardiovascular events. However, little is known about the relation between phosphate levels and improvement of cardiac function in chronic heart failure (CHF) patients who underwent cardiac resynchronization therapy (CRT). The purpose of this study was to examine whether serum phosphate levels were able to predict responders to CRT and adverse cardiac events.

METHODS

The study population consisted of 30 CHF patients (24 males, mean age 65.7±8.5 years) who received CRT with defibrillator (CRT-D) implantation. Levels of serum phosphate were measured before, and 6 months after, CRT-D implantation. Left ventricular end-diastolic volume and end-systolic volume were assessed simultaneously by echocardiography. In addition, the rate of re-hospitalization due to worsening of heart failure was investigated. All patients were divided into 2 groups: responders (Group-R, n=18) and non-responders (Group-NR, n=12) to CRT-D. Responders were defined as patients who showed >15% reduction in left ventricular end-systolic volume. We compared these parameters between the 2 groups.

RESULTS

Serum phosphate levels were significantly lower in Group-R than in Group-NR (3.3±0.2 vs. 3.7±0.4 mg/dL, p=0.01). The rate of re-hospitalization was lower in Group-R than in Group-NR (0% vs. 33%, p=0.018). Multivariate analysis showed that serum phosphate levels had a predictive power to determine responders to CRT (odds ratio 0.008, 95% confidence interval 0.000-0.348, p=0.015).

CONCLUSIONS

These results suggest that serum phosphate levels might predict both responders to CRT, and adverse cardiac events, in CHF patients with CRT-D.

Relationship between residual renal function and serum fibroblast growth factor 23 in patients on peritoneal dialysis

Fibroblast growth factor 23 (FGF23) levels in dialysis patients are influenced by various factors, including phosphorus load. However, the clinical parameters that determine serum FGF23 levels in patients on peritoneal dialysis (PD) remain unclear. The aim of the present study was to examine the effects of clinical factors, on serum FGF23 levels, with an emphasis on residual renal function (RRF). This cross-sectional study included 56 outpatients undergoing PD therapy. Urine volume ≥ 100 mL/day or renal creatinine (Cr) clearance was used as a surrogate marker for RRF. Clinical characteristics were compared between patients with and without RRF. Linear regression analysis was conducted with serum FGF23 level as the dependent variable and renal Cr clearance as the main independent variable. The median and interquartile range of serum FGF23 levels were 5970 (1451-11,688) pg/mL. Patients with RRF showed higher urinary and total phosphate eliminations, and lower serum FGF23 and phosphate levels than patients without RRF. Multivariate linear regression analysis showed that the renal Cr clearance and serum phosphate and dialysis history were negatively associated with serum FGF23 levels, even after adjusting for potential confounders including peritoneal Cr clearance. Further, the predictabilities of serum FGF23 were comparable among renal Cr clearance, Kt/V for urea, and renal phosphate clearance. RRF determined by renal Cr clearance or residual urine volume is an independent negative determinant of serum FGF23 levels in PD patients.