Sex, Age, and the Association of Serum Phosphorus With All-Cause Mortality in Adults With Normal Kidney Function

Pharmacology of Mammalian Na+-Dependent Transporters of Inorganic Phosphate

Inorganic phosphate (Pi) is an essential component of many biologically important molecules such as DNA, RNA, ATP, phospholipids, or apatite. It is required for intracellular phosphorylation signaling events and acts as pH buffer in intra- and extracellular compartments. Intestinal absorption, uptake into cells, and renal reabsorption depend on a set of different phosphate transporters from the SLC20 (PiT transporters) and SLC34 (NaPi transporters) gene families. The physiological relevance of these transporters is evident from rare monogenic disorders in humans affecting SLC20A2 (Fahr's disease, basal ganglia calcification), SLC34A1 (idiopathic infantile hypercalcemia), SLC34A2 (pulmonary alveolar microlithiasis), and SLC34A3 (hereditary hypophosphatemic rickets with hypercalciuria). SLC34 transporters are inhibited by millimolar concentrations of phosphonoformic acid or arsenate while SLC20 are relatively resistant to these compounds. More recently, a series of more specific and potent drugs have been developed to target SLC34A2 to reduce intestinal Pi absorption and to inhibit SLC34A1 and/or SLC34A3 to increase renal Pi excretion in patients with renal disease and incipient hyperphosphatemia. Also, SLC20 inhibitors have been developed with the same intention. Some of these substances are currently undergoing preclinical and clinical testing. Tenapanor, a non-absorbable Na+/H+-exchanger isoform 3 inhibitor, reduces intestinal Pi absorption likely by indirectly acting on the paracellular pathway for Pi and has been tested in several phase III trials for reducing Pi overload in patients with renal insufficiency and dialysis.

Calcium-Phosphorus Product Is Associated with Adverse Prognosis in Hospitalized Patients with Heart Failure and Chronic Kidney Disease

It has been reported that high levels of calcium-phosphorus (Ca-P) product are an indicator of coronary calcification and mortality risk in patients undergoing chronic hemodialysis. In the present study, we aimed to evaluate the significance of Ca-P product to predict the prognosis of patients with heart failure (HF) and chronic kidney disease (CKD). We conducted a prospective observational study of 793 patients with decompensated HF and CKD, and measured the value of Ca-P product. The cut-off value was obtained from the survival classification and regression tree (CART) analysis to predict post-discharge all-cause mortality and/or worsening HF, and the patients were divided into 2 groups: a high group (Ca-P product > 28, n = 594) and a low group (Ca-P product ≤ 28, n = 199). We compared the patient baseline characteristics and post-discharge prognosis between the 2 groups. The age as well as the prevalence of male sex, ischemic etiology, and anemia were significantly higher in the low group than in the high group. In contrast, there was no difference in echocardiographic parameters between the 2 groups. In the Kaplan-Meier analysis (mean follow-up 1089 days), all-cause mortality and/or worsening HF event rates were higher in the low group than in the high group (log-rank P = 0.001). In the multivariable Cox proportional hazard analysis, lower Ca-P product was found to be an independent predictor of all-cause mortality and/or worsening HF (hazard ratio 0.981, P = 0.031). Lower Ca-P product predicts adverse prognosis in patients with HF and CKD.

Early aging and premature vascular aging in chronic kidney disease

Aging is the progressive decline of body functions and a number of chronic conditions can lead to premature aging characterized by frailty, a diseased vasculature, osteoporosis, and muscle wasting. One of the major conditions associated with premature and accelerated aging is chronic kidney disease (CKD), which can also result in early vascular aging and the stiffening of the arteries. Premature vascular aging in CKD patients has been considered as a marker of prognosis of mortality and cardiovascular morbidity and therefore requires further attention. Oxidative stress, inflammation, advanced glycation end products, fructose, and an aberrant gut microbiota can contribute to the development of early aging in CKD patients. There are several key molecular pathways and molecules which play a role in aging and vascular aging including nuclear factor erythroid 2-related factor 2 (Nrf-2), AMP-activated protein kinase (AMPK), sirtuin 1 (SIRT1), and klotho. Potential therapeutic strategies can target these pathways. Future studies are needed to better understand the importance of premature aging and early vascular aging and to develop therapeutic alternatives for these conditions.

Chronic Kidney Disease and the Exposome of Ageing

The gap between improvements in lifespan and age-related health is widening. Globally, the demographic of ageing is increasing and there has emerged a 'diseasome of ageing', typified by a range of non-communicable diseases which share a common underlying component of a dysregulated ageing process. Within this, chronic kidney disease is an emerging global epidemic.The extensive inter-individual variation displayed in how people age and how their diseasome manifests and progresses, has required a renewed focus on their life course exposures and the interplay between the environment and the (epi)genome. Termed the exposome, life course abiotic and biotic factors have a significant impact on renal health.We explore how the exposome of renal ageing can predispose and affect CKD progression. We discuss how the kidney can be used as a model to understand the impact of the exposome in health and chronic kidney disease and how this might be manipulated to improve health span.Notably, we discuss the manipulation of the foodome to mitigate acceleration of ageing processes by phosphate and to explore use of emerging senotherapies. A range of senotherapies, for removing senescent cells, diminishing inflammatory burden and either directly targeting Nrf2, or manipulating it indirectly via modification of the microbiome are discussed.

Phosphate Dysregulation and Metabolic Syndrome

Phosphorus is one of the most abundant minerals in the human body. It is essential for almost all biochemical activities through ATP formation, intracellular signal transduction, cell membrane formation, bone mineralization, DNA and RNA synthesis, and inflammation modulation through various inflammatory cytokines. Phosphorus levels must be optimally regulated, as any deviations may lead to substantial derangements in glucose homeostasis. Clinical studies have reported that hyperphosphatemia can increase an individual's risk of developing metabolic syndrome. High phosphate burden has been shown to impair glucose metabolism by impairing pancreatic insulin secretion and increasing the risk of cardiometabolic disorders. Phosphate toxicity deserves more attention as metabolic syndrome is being seen more frequently worldwide and should be investigated further to determine the underlying mechanism of how phosphate burden may increase the cardiometabolic risk in the general population.

The Other Way Around: Living With Chronic Kidney Disease From the Perspective of Men

A wealth of evidence has suggested sex (biological) and gender (sociocultural) differences in the prevalence, progression, and outcomes of persons with chronic kidney disease. Much of this evidence tends to emphasize differences in which women are disadvantaged, and less attention is paid to findings in which women are better off or similar to men. However, gender medicine recognizes that men and women have different disease determinants, presentation, and attitudes, and it pertains to both sexes. In this review, we revisit chronic kidney disease through the perspective of men, and illustrate a population segment at need of stringent preventative and management strategies.

Sex-Specific Associations Between Serum Phosphate Concentration and Cardiometabolic Disease: A Cohort Study on the Community-Based Older Chinese Population

PURPOSE

This study aimed to investigate the association between sex-specific baseline serum phosphate and the incidence of new-onset cardiometabolic disease in a cohort of Shanghai-based older Chinese individuals.

PATIENTS AND METHODS

A community cohort of 5000 disease-free Chinese men and women was recruited in 2013 and followed until 2017 for the development of cardiometabolic disease. Participants underwent index and follow-up health screens at the Tongji Medical School affiliated Shanghai East Hospital, including blood biochemistry analysis, anthropometric measurements, interview on health-related behaviors, and clinical evaluation.

RESULTS

Higher baseline serum phosphate (>1.25 mmol/L) was significantly associated with new-onset type-2 diabetes mellitus (HR 1.730, 95% CI 1.127-2.655) and metabolic syndrome (HR 0.640, 95% CI 1.085-2.155) in women. Baseline serum phosphate was associated with age, BMI, waist circumference, SBP, total calcium, bicarbonate, and total cholesterol in women. The estimated risk of developing diabetes mellitus in women with inorganic phosphate >1.25 mmol/L was 14.54%. Inorganic phosphate accounted for 9.2% of the variance explained in a total estimated 14.52% of variance attributed to BMI, total cholesterol, total calcium, waist circumference, and inorganic phosphate.

CONCLUSION

Serum phosphate concentration showed sex-specific associations with diabetes and metabolic syndrome. Higher inorganic phosphate was associated with increased risk of developing diabetes mellitus in women. These findings may be important in the assessment of individualized metabolic risk.

An Expert Perspective on Phosphate Dysregulation With a Focus on Chronic Hypophosphatemia

Because of their rarity, diseases characterized by chronic hypophosphatemia can be underrecognized and suboptimally managed, resulting in poor clinical outcomes. Moreover, serum phosphate may not be measured routinely in primary care practice. Authors participated in several working sessions to advance the understanding of phosphate homeostasis and the causes, consequences, and clinical implications of chronic hypophosphatemia. Phosphate levels are regulated from birth to adulthood. Dysregulation of phosphate homeostasis can result in hypophosphatemia, which becomes chronic if phosphate levels cannot be normalized. Chronic hypophosphatemia may be underrecognized as serum phosphate measurement is not always part of routine analysis in the primary care setting and results might be misinterpreted, for instance, due to age-specific differences not being accounted for and circadian variations. Clinical consequences of chronic hypophosphatemia involve disordered endocrine regulation, affect multiple organ systems, and vary depending on patient age and the underlying disorder. Signs and symptoms of chronic hypophosphatemic diseases that manifest during childhood or adolescence persist into adulthood if the disease is inadequately managed, resulting in an accumulation of clinical deficits and a progressive, debilitating impact on quality of life. Early identification and diagnosis of patients with chronic hypophosphatemia is crucial, and clinical management should be started as soon as possible to maximize the likelihood of improving health outcomes. Furthermore, in the absence of a universally accepted description for "chronic hypophosphatemia," a definition is proposed here that aims to raise awareness of these diseases, facilitate diagnosis, and guide optimal phosphate management strategies by improving monitoring and assessment of patient response to treatment. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Long-term risk of all-cause mortality in live kidney donors: a matched cohort study

Background

Long-term outcomes of live kidney donors remain controversial, although this information is crucial for selecting potential donors. Thus, this study compared the long-term risk of all-cause mortality between live kidney donors and healthy control.

Methods

We performed a retrospective cohort study including donors from seven tertiary hospitals in South Korea. Persons who underwent voluntary health screening were included as controls. We created a matched control group considering age, sex, era, body mass index, baseline hypertension, diabetes, estimated glomerular filtration rate, and dipstick albuminuria. The study outcome was progression to end-stage kidney disease (ESKD), and all-cause mortality as identified in the linked claims database.

Results

We screened 1,878 kidney donors and 78,115 health screening examinees from 2003 to 2016. After matching, 1,701 persons remained in each group. The median age of the matched study subjects was 44 years, and 46.6% were male. Among the study subjects, 2.7% and 16.6% had underlying diabetes and hypertension, respectively. There were no ESKD events in the matched donor and control groups. There were 24 (1.4%) and 12 mortality cases (0.7%) in the matched donor and control groups, respectively. In the age-sex adjusted model, the risk for all-cause mortality was significantly higher in the donor group than in the control group. However, the significance was not retained after socioeconomic status was included as a covariate (adjusted hazard ratio, 1.82; 95% confidence interval, 0.87-3.80).

Conclusion

All-cause mortality was similar in live kidney donors and matched non-donor healthy controls with similar health status and socioeconomic status in the Korean population.

Phosphate Concentrations and Modifying Factors in Healthy Children From 12 to 24 Months of Age

CONTEXT

Phosphate homeostasis and its modifiers in early childhood are inadequately characterized.

OBJECTIVE

To determine physiological plasma phosphate concentration and modifying factors in healthy infants at 12 to 24 months of age.

DESIGN

This study included 525 healthy infants (53% girls), who participated in a randomized vitamin D intervention trial and received daily vitamin D3 supplementation of either 10 or 30 μg from age 2 weeks to 24 months. Biochemical parameters were measured at 12 and 24 months. Dietary phosphate intake was determined at 12 months.

MAIN OUTCOME MEASURES

Plasma phosphate concentrations at 12 and 24 months of age.

RESULTS

Mean (SD) phosphate concentration decreased from 12 months (1.9 ± 0.15 mmol/L) to 24 months (1.6 ± 0.17 mmol/L) of age (P < 0.001 for repeated measurements). When adjusted by covariates, such as body size, creatinine, serum 25-hydroxyvitamin D, intact and C-terminal fibroblast growth factor 23, mean plasma phosphate was higher in boys than girls during follow-up (P = 0.019). Phosphate concentrations were similar in the vitamin D intervention groups (P > 0.472 for all). Plasma iron was associated positively with plasma phosphate at both time points (B, 0.006 and 0.005; 95% CI, 0.004-0.009 and 0.002-0.008; P < 0.001 at both time points, respectively). At 24 months of age, the main modifier of phosphate concentration was plasma creatinine (B, 0.007; 95% CI 0.003-0.011, P < 0.001).

CONCLUSION

Plasma phosphate concentration decreased from age 12 to 24 months. In infants and toddlers, the strongest plasma phosphate modifiers were sex, iron, and creatinine, whereas vitamin D supplementation did not modify phosphate concentrations.

Jak1/Stat3 Activation Alters Phosphate Metabolism Independently of Sex and Extracellular Phosphate Levels

INTRODUCTION

Phosphate homeostasis is regulated by a complex network involving the parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and calcitriol acting on several organs including the kidney, intestine, bone, and parathyroid gland. Previously, we showed that activation of the Janus kinase 1 (Jak1)-signal transducer and activator of transcription 3 (Stat3) signaling pathway leads to altered mineral metabolism with higher FGF23 levels, lower PTH, and higher calcitriol levels. Here, we investigated if there are sex differences in the role of Jak1/Stat3 signaling pathway on phosphate metabolism and if this pathway is sensitive to extracellular phosphate alterations.

METHODS

We used a mouse model (Jak1S645P+/-) that resembles a constitutive activating mutation of the Jak1/Stat3 signaling pathway in humans and analyzed the impact of sex on mineral metabolism parameters. Furthermore, we challenged Jak1S645P+/- male and female mice with a high (1.2% w/w) and low (0.1% w/w) phosphate diet and a diet with phosphate with organic origin with lower bioavailability.

RESULTS

Female mice, as male mice, showed higher intact FGF23 levels but no phosphaturia, and higher calcitriol and lower PTH levels in plasma. A phosphate challenge did not alter the effect of Jak1/Stat3 activation on phosphate metabolism for both genders. However, under a low phosphate diet or a diet with lower phosphate availability, the animals showed a tendency to develop hypophosphatemia. Moreover, male and female mice showed similar phosphate metabolism parameters. The only exception was higher PTH levels in male mice than those in females.

DISCUSSION/CONCLUSION

Sex and extracellular phosphate levels do not affect the impact of Jak1/Stat3 activation on phosphate metabolism.

Association between serum phosphate and mortality in critically ill patients: a large retrospective cohort study

OBJECTIVES

This research aims to explore the impact of serum phosphate on the mortality of critically ill patients.

DESIGN

A retrospective large cohort study.

SETTING

Our data were extracted from a publicly accessible database named 'Multiparameter Intelligent Monitoring in Intensive Care Database III'.

PARTICIPANTS

27 131 patients were included by clear definitions of selection and exclusion criteria.

INTERVENTIONS

We used initial phosphate at admission as a design variable. Patients were divided into six groups with different serum phosphate levels and five groups at different intensive care unit (ICU) departments.

PRIMARY AND SECONDARY OUTCOMES

28-day and 90-day mortality were primary outcomes. All-cause mortality and length of stay ICU were secondary outcomes.

RESULTS

Patients with very-high-normal serum phosphate, hypophosphataemia and hyperphosphataemia had worse outcomes. And the relationship between serum phosphate and the probability of 28-day or 90-day mortality had a linear relationship. After adjustment for potential confounders, hypophosphataemia and hyperphosphataemia were not significantly associated with 28-day or 90-day mortality. Nevertheless, at the medical ICU, hyperphosphataemia was associated with increased 28-day or 90-day mortality (HR=0.64, 95% CI 0.48 to 0.84, p=0.0017; HR=0.72, 95% CI 0.57 to 0.91, p=0.0067, respectively), using group 2 (≥2.5 mg/dL and <3.0 mg/dL) as the reference group.

CONCLUSIONS

Patients with very-high-normal serum phosphate also had worse outcomes, it might be necessary to re-evaluate the definitions of the normal reference range for serum phosphate. Hypophosphataemia and hyperphosphataemia are not the independent risk factors of 28-day or 90-day ICU mortality, which leads us to consider whether phosphate monitoring is not a necessary measure in critically ill patients. But hyperphosphataemia was associated with increased 28-day or 90-day mortality at the medical ICU, which emphasises the potential importance of early diagnosis and treatment of hyperphosphataemia for the patients who were admitted to the medical ICU.

Association between ultrapocessed food and chronic kidney disease

The modern diet is closely linked to the consumption of processed foods, causing an increase in the intake of salt, simple sugars, phosphorus and added potassium. This excess intake is associated with an increased risk of obesity, diabetes, hypertension and chronic kidney disease (CKD). CKD, which according to data from the ENRICA study affects 15% of the population, magnifies its impact due to the higher prevalence of diabetes and hypertension and due to limitations in the management of sodium and phosphorus. The intake of these products far exceeds the established recommendations, assuming 72% of total sodium, 25%-35% of phosphorus, 12%-18% of potassium and exceeding 10% of the caloric intake in simple sugars. Measures are necessary to reduce their contribution through nutritional advice, labeling review, education campaigns on healthy habits, fees and institutional actions that involve food safety agencies, industry, distribution and scientific societies.

Association between ultrapocessed food and chronic kidney disease

The modern diet is closely linked to the consumption of processed foods, causing an increase in the intake of salt, simple sugars, phosphorus and added potassium. This excess intake is associated with an increased risk of obesity, diabetes, hypertension and chronic kidney disease (CKD). CKD, which according to data from the ENRICA study affects 15% of the population, magnifies its impact due to the higher prevalence of diabetes and hypertension and due to limitations in the management of sodium and phosphorus. The intake of these products far exceeds the established recommendations, assuming 72% of total sodium, 25-35% of phosphorus, 12-18% of potassium and exceeding 10% of the caloric intake in simple sugars. Measures are necessary to reduce their contribution through nutritional advice, labeling review, education campaigns on healthy habits, fees and institutional actions that involve food safety agencies, industry, distribution and scientific societies.

Hyperphosphatemia rather than hypophosphatemia indicates a poor prognosis in patients with sepsis

BACKGROUND

Sepsis is the leading cause of hospitalization and death in the intensive care unit. It is vital to identify high-risk patients with poor prognosis in the early stages of sepsis. We aimed to investigate the prognostic value of serum phosphorus levels for sepsis.

METHODS

The data of 4767 patients with sepsis were collected from the Multiparameter Intelligent Monitoring in Intensive Care III database. The Locally Weighted Scatterplot Smoothing technique and Kaplan-Meier analysis were used to test the crude relationship between serum phosphorus levels and mortality or overall survival. The multivariable logistic regression was used to further analyze the relationship between serum phosphorus levels and in-hospital mortality. The subgroup analysis was performed according to renal failure, use of vasopressin and the Sequential Organ Failure Assessment (SOFA) score.

RESULTS

Only hyperphosphatemia significantly correlated with in-hospital mortality [odds ratio (OR) 1.48; 95% confidence interval (CI) 1.19-1.85], while the correlation between hypophosphatemia and in-hospital mortality was not significant (OR 0.91; 95% CI 0.70-1.19). The interactions between serum phosphorus and renal failure, use of vasopressin or the SOFA score were not significant.

CONCLUSIONS

Hyperphosphatemia rather than hypophosphatemia indicates a poor prognosis in patients with sepsis.

Association between serum phosphorus and mortality in NHANES 2003-2006: the effect of gender and renal function

BACKGROUND

The impact of high serum phosphorus in the general population is still debated. Studies are heterogeneous, most lack an adjustment for parathyroid hormone, vitamin D and phosphorus intake and the effect might differ by gender and renal function. We investigated the association between serum phosphorus and mortality in American adults.

METHODS

We prospectively analyzed 5698 non-pregnant and non-CKD adults from the National Health and Nutrition Examination Survey (NHANES) 2003-2006. Serum phosphorus and potential confounders including parathyroid hormone, 25(OH)vitamin D and phosphorus intake were evaluated. All-cause, cardiovascular- and cancer-related deaths were recorded through December 31st, 2015. Sex-specific terciles of serum phosphorus were used to fit adjusted Cox proportional hazard models for mortality. Analysis was stratified by gender and renal function.

RESULTS

A total of 590 deaths were recorded over a median follow-up of 81 months. Women showed higher serum phosphorus than men. The adjusted hazard ratio (HR) for all-cause mortality was 1.35 (95% CI 1.08-1.58) (p = 0.033) for the third tercile (versus second tercile). This increased risk was present in participants with estimated glomerular filtration rate (eGFR) below 90 ml/min/1.73 m² but not above, although interaction was not significant (p = 0.12). Interaction by gender, phosphorus intake, PTH and fasting time was also not detected. For cardiovascular and cancer mortality, the adjusted HR was 0.81 (95% CI 0.33-2.00) (p = NS) and 1.45 (95% CI 0.77-2.72) (p = NS), respectively.

CONCLUSIONS

We demonstrated that the highest tercile of serum phosphorus is associated with increased all-cause mortality, irrespective of PTH, 25(OH)vitamin D or phosphorus intake. This association may differ by gender and renal function, but larger studies testing for effect modification are needed.

High-phosphorus diet controlled for sodium elevates blood pressure in healthy adults via volume expansion

Whether increasing exposure to dietary phosphorus can lead to adverse clinical outcomes in healthy people is not clear. In this open‐label prospective cross‐over study, we are to explore the impact of various dietary phosphorus intake on mineral, sodium metabolisms and blood pressure in young healthy adults. There were 3 separate study periods of 5 days, each with a 5 days washout period between different diets interventions. Six young healthy male volunteers with normal nutrition status were recruited in Phase I Clinical Research Center and sequentially exposed to the following diets: (a) normal‐phosphorus diet (NPD): 1500 mg/d, (b) low‐phosphorus diet (LPD): 500 mg/d, (c) high‐phosphorus diet (HPD): 2300 mg/d. HPD induced a significant rise in daily average serum phosphate (1.47 ± 0.02 mmol/L [4.56 ± 0.06 mg/dl]) compared to NPD (1.34 ± 0.02 mmol/L [4.15 ± 0.06 mg/dL]) and LPD (1.17 ± 0.02 mmol/L [3.63 ± 0.06 mg/dL]) (p < .05). Daily average levels of serum parathyroid hormone and fibroblast growth factor 23 in HPD were significantly higher, and serum 1,25(OH)₂D₃ was remarkably lower than those in LPD. HPD induced a significant decrease in daily average serum aldosterone and an increase in daily average atrial natriuretic peptide level compared to LPD. The 24‐hour urine volume in HPD subjects was less than that in LPD subjects. HPD significantly increased daily average systolic blood pressure by 6.02 ± 1.24 mm Hg compared to NPD and by 8.58 ± 1.24mm Hg compared to LPD (p < .05). Our study provides the first evidence that 5‐day high‐phosphorus diet can induce elevation in SBP in young healthy adults, which may due to volume expansion.

Serum phosphorus levels are associated with carotid intima-media thickness in asymptomatic postmenopausal women

Objective:

Serum phosphorous is a significant risk factor for increased carotid intima-media thickness. Increased thickness of the carotid intima is a known cause of cardiovascular disease. Coronary heart disease is a significant cause of mortality and morbidity in postmenopausal women. This study aimed to compare the relationship between serum phosphorous concentration and carotid intima-media thickness in healthy asymptomatic postmenopausal women.

Methods:

A retrospective review of the medical records from a health checkup center in Gangnam Severance hospital between March 2007 and September 2017 was conducted. We examined asymptomatic postmenopausal female patients with age range between 56 and 66 (N = 361) who underwent measurement of carotid intima-media thickness by B-mode ultrasonography. The physiological variables analyzed included mean blood pressure, body mass index, renal function (serum creatinine and estimated glomerular filtration rate), cholesterol levels (total cholesterol, triglyceride, and high- and low-density lipoprotein), serum phosphorous, calcium, electrolytes, diabetic status, hypertension, and albumin.

Results:

Pearson correlation test showed that carotid intima-media thickness was significantly associated with age (r = 0.192, P < 0.001), mean blood pressure (r = 0.116, P = 0.029), diastolic blood pressure (r = 0.146, P = 0.029), serum phosphorous (r = 0.134, P = 0.012), and lactate dehydrogenase (r = 0.106, P = 0.047). On the basis of age-adjusted multivariate linear regression analysis, carotid intima-media thickness was significantly correlated with serum phosphorous levels (β = 0.273, P = 0.022) in asymptomatic menopausal women. Increased carotid intima-media thickness (cut-off 1.5 mm) was detected, although serum phosphorous was within the normal range (2.8-4.5 mg/dL).

Conclusions:

Serum phosphorus concentration is significantly associated with carotid intima-media thickness in asymptomatic menopausal women.

Effects of Potassium or Sodium Supplementation on Mineral Homeostasis: A Controlled Dietary Intervention Study

CONTEXT

Although dietary potassium and sodium intake may influence calcium-phosphate metabolism and bone health, the effects on bone mineral parameters, including fibroblast growth factor 23 (FGF23), are unclear.

OBJECTIVE

Here, we investigated the effects of potassium or sodium supplementation on bone mineral parameters.

DESIGN, SETTING, PARTICIPANTS

We performed a post hoc analysis of a dietary controlled randomized, blinded, placebo-controlled crossover trial. Prehypertensive individuals not using antihypertensive medication (n = 36) received capsules containing potassium chloride (3 g/d), sodium chloride (3 g/d), or placebo. Linear mixed-effect models were used to estimate treatment effects.

RESULTS

Potassium supplementation increased plasma phosphate (from 1.10 ± 0.19 to 1.15 ± 0.19 mmol/L, P = 0.004), in line with an increase in tubular maximum of phosphate reabsorption (from 0.93 ± 0.21 to 1.01 ± 0.20 mmol/L, P < 0.001). FGF23 decreased (114.3 [96.8-135.0] to 108.5 [93.5-125.9] RU/mL, P = 0.01), without change in parathyroid hormone and 25-hydroxy vitamin D3. Fractional calcium excretion decreased (from 1.25 ± 0.50 to 1.11 ± 0.46 %, P = 0.03) without change in plasma calcium. Sodium supplementation decreased both plasma phosphate (from 1.10 ± 0.19 to 1.06 ± 0.21 mmol/L, P = 0.03) and FGF23 (from 114.3 [96.8-135.0] to 108.7 [92.3-128.1] RU/mL, P = 0.02). Urinary and fractional calcium excretion increased (from 4.28 ± 1.91 to 5.45 ± 2.51 mmol/24 hours, P < 0.001, and from 1.25 ± 0.50 to 1.44 ± 0.54 %, P = 0.004, respectively).

CONCLUSIONS

Potassium supplementation led to a decrease in FGF23, which was accompanied by increase in plasma phosphate and decreased calcium excretion. Sodium supplementation reduced FGF23, but this was accompanied by decrease in phosphate and increase in fractional calcium excretion. Our results indicate distinct effects of potassium and sodium intake on bone mineral parameters, including FGF23.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01575041.

Klotho, Aging, and the Failing Kidney

Klotho has been recognized as a gene involved in the aging process in mammals for over 30 years, where it regulates phosphate homeostasis and the activity of members of the fibroblast growth factor (FGF) family. The α-Klotho protein is the receptor for Fibroblast Growth Factor-23 (FGF23), regulating phosphate homeostasis and vitamin D metabolism. Phosphate toxicity is a hallmark of mammalian aging and correlates with diminution of Klotho levels with increasing age. As such, modulation of Klotho activity is an attractive target for therapeutic intervention in the diseasome of aging; in particular for chronic kidney disease (CKD), where Klotho has been implicated directly in the pathophysiology. A range of senotherapeutic strategies have been developed to directly or indirectly influence Klotho expression, with varying degrees of success. These include administration of exogenous Klotho, synthetic and natural Klotho agonists and indirect approaches, via modulation of the foodome and the gut microbiota. All these approaches have significant potential to mitigate loss of physiological function and resilience accompanying old age and to improve outcomes within the diseasome of aging.

Nrf2 in early vascular ageing: Calcification, senescence and therapy

Under normal physiological conditions, free radical generation and antioxidant defences are balanced, and reactive oxygen species (ROS) usually act as secondary messengers in a plethora of biological processes. However, when this balance is impaired, oxidative stress develops due to imbalanced redox homeostasis resulting in cellular damage. Oxidative stress is now recognized as a trigger of cellular senescence, which is associated with multiple chronic 'burden of lifestyle' diseases, including atherosclerosis, type-2 diabetes, chronic kidney disease and vascular calcification; all of which possess signs of early vascular ageing. Nuclear factor erythroid 2-related factor 2 (Nrf2), termed the master regulator of antioxidant responses, is a transcription factor found to be frequently dysregulated in conditions characterized by oxidative stress and inflammation. Recent evidence suggests that activation of Nrf2 may be beneficial in protecting against vascular senescence and calcification. Both natural and synthetic Nrf2 agonists have been introduced as promising drug classes in different phases of clinical trials. However, overexpression of the Nrf2 pathway has also been linked to tumorigenesis, which highlights the requirement for further understanding of pathways involving Nrf2 activity, especially in the context of cellular senescence and vascular calcification. Therefore, comprehensive translational pre-clinical and clinical studies addressing the targeting capabilities of Nrf2 agonists are urgently required. The present review discusses the impact of Nrf2 in senescence and calcification in early vascular ageing, with focus on the potential clinical implications of Nrf2 agonists and non-pharmacological Nrf2 therapeutics.

Obesity, smoking habits, and serum phosphate levels predicts mortality after life-style intervention

Background

Life-style interventions, including smoking cessation and weight control are of importance for managing future escalating prevalence of obesity. Smoking habits and obesity have jointly great impact on mortality, however mechanisms behind the effect and variables involved in the obesity paradox is still unknown.

Objectives

This study examines risk factors for all-cause, cardiovascular, and cancer mortality in males and females with high cardiovascular risk, mediated by smoking habits, body mass index (BMI, kg/m²), and serum phosphate (S-P) levels.

Methods

Patients were admitted to the Vindeln Patient Education Center in groups of 30 for a four-week residential comprehensive program (114 hours) focusing on smoking cessation, stress reduction, food preferences and selections, and physical exercise. The follow-up, in years from 1984 to 2014 corresponds to 30 years. This study included 2,504 patients (1,408 females and 1,096 males). Cox regression analysis was used to assess mortality risk associated with smoking habits, low and high BMI, and low and high S-P levels.

Results

High BMI (>34,2 kg/m²), current smoking, type 2 diabetes mellitus (T2DM), high serum calcium (S-Ca), mmol/L and high systolic blood pressure (SBP, mmHg) were associated with all-cause mortality irrespective of sex. Former and current smoking females had a high all-cause mortality (adjusted hazard ratio [HR] 1.581; 95% CI 1.108–2.256, adjusted hazard ratio [HR] 1.935; 95% CI 1.461–2.562, respectively) while current smoking and high BMI increased risk for cardiovascular mortality (adjusted hazard ratio [HR] 3.505; 95% CI 2.140–5.740 and [HR] 1.536; 95% CI 1.058–2.231, respectively). Neither low nor high levels of S-P predicted all-cause, cardiovascular disease (CVD) and cancer mortality in males or females while low levels of S-P predicted all-cause mortality in smokers (adjusted hazard ratio [HR] 1.713; 95% CI 1.211–2.424). In non-smokers, low BMI (<27.6 kg/m²) was protecting and high BMI a risk for all-cause mortality. In males, ischemic heart disease (IHD), and low serum albumin (S-Alb) were associated with all-cause mortality. In females, an interaction between high BMI and smoking (HbmiSM) decreased the cardiovascular mortality (adjusted hazard ratio [HR] 0.410; 95% CI 0.179–0.937, respectively).

Conclusions

High BMI and current smoking were associated with all-cause mortality in both males and females in the present high cardiovascular-risk cohort. In current smokers and non-smokers, T2DM and high S-Ca were associated with an increase in all-cause mortality, while low S-P was associated with all-cause mortality in smokers. Interaction between high BMI and smoking contribute to the obesity paradox by being protective for cardiovascular mortality in females.

Normal-range emergency department serum phosphorus levels and all-cause mortality

PURPOSE OF THE STUDY

Hypophosphataemia and hyperphosphataemia are frequently encountered in hospitalised patients and are associated with significant clinical consequences. However, the prognostic value of normal-range phosphorus levels on all-cause mortality and hospitalisations is not well established. Therefore, we examined the association between normal-range phosphorus levels, all-cause mortality and hospitalisations in patients presenting to the emergency department of a tertiary medical centre in Israel.

STUDY DESIGN

A retrospective analysis of patients presenting to the Chaim Sheba Medical Center emergency department between 2012 and 2018. The cohort was divided into quartiles based on emergency department phosphorus levels: 'very-low-normal' (p ≥ 2 mg/dL and p ≤ 2.49 mg/dL), 'low-normal' (p ≥ 2.5 mg/dL and p ≤ 2.99 mg/dL), 'high-normal' (p≥  3 mg/dL and p≤3.49 mg/dL) and 'very-high-normal' (p ≥  3.5 mg/dL and p ≤ 4 mg/dL). We analysed the association between emergency department phosphorus levels, hospitalisation rate and 30-day and 90-day all-cause mortality.

RESULTS

Our final analysis included 223 854 patients with normal-range phosphorus levels. Patients with 'very-low-normal' phosphorus levels had the highest mortality rate. Compared with patients with 'high-normal' phosphorus levels, patients with 'very-low-normal' levels had increased 30-day all-cause mortality (OR 1.3, 95% CI 1.1 to 1.4, p<0.001), and increased 90-day all-cause mortality (OR 1.2, 95% CI 1.1 to 1.3, p<0.001). Lower serum phosphorus levels were also associated with a higher hospitalisation rate, both for the internal medicine and general surgery wards (p<0.001).

CONCLUSIONS

Lower phosphorus levels, within the normal range, are associated with higher 30-day and 90-day all-cause mortality and hospitalisation rate.

Long-term Mortality Risks Among Living Kidney Donors in Korea

RATIONALE & OBJECTIVE

Living kidney donors may have a higher risk for death and kidney failure. This study aimed to investigate the long-term mortality experience of living kidney donors compared with members of the general public in Korea who underwent voluntary health examinations.

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

We first calculated standardized mortality ratios for 1,292 Korean living kidney donors who underwent donor nephrectomy between 1982 and 2016 and 72,286 individuals who underwent voluntary health examinations between 1995 and 2016. Next we compared survival between the 1,292 living kidney donors and a subgroup of the health examination population (n=33,805) who had no evident contraindications to living kidney donation at the time of their examinations. Last, a matched comparator group was created from the health examination population without apparent contraindication to donation by matching 4,387 of them to donors (n=1,237) on age, sex, body mass index, estimated glomerular filtration rate, urine dipstick albumin excretion, previously diagnosed hypertension and diabetes, and era.

EXPOSURES

Donor nephrectomy.

OUTCOMES

All-cause mortality and other clinical outcomes after kidney donation.

ANALYTICAL APPROACH

First, standardized mortality ratios were calculated separately for living kidney donors and the health examination population standardized to the general population. Second, we used Cox regression analysis to compare mortality between living kidney donors versus the subgroup of the health examination population without evident donation contraindications. Third, we used Cox regression analysis to compare mortality between living kidney donors and matched comparators from the health examination population without apparent contraindication to donation.

RESULTS

The living kidney donors and health examination population had excellent survival rates compared with the general population. 52 (4.0%) of 1,292 kidney donors died during a mean follow-up of 12.3±8.1 years and 1,072 (3.2%) of 33,805 in the health examiner subgroup without donation contraindications died during a mean follow-up of 11.4±6.1 years. Donor nephrectomy did not elevate the hazard for mortality after multivariable adjustment in kidney donors and the 33,805 comparators (adjusted HR, 1.01; 95% CI, 0.71-1.44; P=0.9). Moreover, living donors showed a similar mortality rate compared with the group of matched healthy comparators.

LIMITATIONS

Donors from a single transplantation center. Residual confounding owing to the observational study design.

CONCLUSIONS

Kidney donors experienced long-term rates of death comparable to nondonor comparators with similar health status.

Higher serum phosphorus predicts residual renal function loss in male but not female incident peritoneal dialysis patients

BACKGROUND

Elevated serum phosphorus level is a risk factor for progression of chronic kidney disease in non-dialysis patients. However, the association of serum phosphorus level with residual renal function (RRF) loss among incident continuous ambulatory peritoneal dialysis (CAPD) patients remains unclear.

METHODS

We performed a retrospective analysis of prospectively collected cohort of 1245 incident CAPD patients from January 2006 to December 2015 and followed up until December 2017. Patients were stratified into tertiles according to baseline serum phosphorus levels. RRF loss was defined as residual glomerular filtration rate (mL/min/1.73 m²) reaching zero or estimated urine output less than 200 mL/day on two successive clinic visits. Propensity-score matched Cox's proportional hazards and competing risk models were performed to examine the association of serum phosphorus with RRF loss.

RESULTS

A total of 421 (33.82%) patients had loss of RRF over a median follow-up of 26.23 months. In the entire cohort, elevated serum phosphorus was associated with increased risk for RRF loss after adjustment. In the propensity-score matched cohort, patients in the 3rd tertile of serum phosphorus had a 51% higher risk of RRF loss than those in the combination of the 1st and 2nd tertiles. Furthermore, the association of serum phosphorus level with RRF loss differed by sex (interaction P = 0.018). The adjusted HRs per 1 mg/dL increase in serum phosphorus level of RRF loss were 1.32 (95% CI 1.15-1.50, P < 0.001) for male and 1.03 (95% CI 0.87-1.21, P = 0.750) for female, respectively. These findings persisted in competing risk analysis.

CONCLUSION

Higher serum phosphorus levels independently predicts RRF loss in men treated with CAPD.

Association of Fibroblast Growth Factor 23 With Recurrent Cardiovascular Events in Patients After an Acute Coronary Syndrome: A Secondary Analysis of a Randomized Clinical Trial

Importance

Elevated fibroblast growth factor 23 (FGF-23) concentrations are associated with myocardial fibrosis and renin-angiotensin system upregulation, potentially providing prognostic information distinct from standard cardiovascular (CV) biomarkers.

Objective

To evaluate the association of FGF-23 with recurrent CV events in patients after an acute coronary syndrome (ACS).

Design, Setting, and Participants

C-terminal FGF-23 was measured in plasma samples using an established enzyme-linked immunosorbent assay system for 4947 patients within 30 days of ACS (median, 14 days) and with 1 additional CV risk factor in the Stabilization of Plaques Using Darapladib-Thrombolysis in Myocardial Infarction 52 (SOLID-TIMI 52) trial of the lipoprotein-associated phospholipase A2 inhibitor darapladib vs placebo performed from December 1, 2009, to April 24, 2014 (median follow-up, 2.5 years). Analyses were adjusted for clinical risk factors, renal function, and established cardiorenal biomarkers. This secondary analysis was performed from September 25, 2014, to October 1, 2017.

Exposure

The FGF-23 concentration at baseline.

Main Outcomes and Measures

The primary end point for this post hoc analysis was the composite of CV death or hospitalization for heart failure.

Results

In this study, baseline FGF-23 concentrations were available for 4947 patients (median age, 64.0 years; interquartile range, 59.0-71.0 years; 1276 [25.8%] female). Patients with higher FGF-23 concentrations were older and more likely female, with a greater proportion of hypertension, diabetes, and previous myocardial infarction. After multivariable adjustment for baseline clinical characteristics and established biomarkers (high-sensitivity troponin I, brain-type natriuretic peptide, and high-sensitivity C-reactive protein), FGF-23 concentration in the top quartile was independently associated with an increased risk of CV death or heart failure hospitalization (adjusted hazard ratio [HR], 2.35; 95% CI, 1.82-3.02; P < .001) and its individual components. Elevated FGF-23 concentration was also associated with an increased risk of all-cause mortality (adjusted HR, 2.27; 95% CI, 1.73-2.97; P < .001) and CV death, myocardial infarction, or stroke (adjusted HR, 1.42; 95% CI, 1.17-1.71; P < .001). When analyses were stratified by patient sex, the association between FGF-23 and CV risk, including CV death or heart failure, appeared to be attenuated in women (adjusted HR, 1.11; 95% CI, 0.70-1.76; P = .67) compared with men (HR, 3.11; 95% CI, 2.29-4.22; P < .001; P < .001 for interaction).

Conclusions and Relevance

In patients stabilized after ACS, elevated FGF-23 concentrations may be associated with recurrent major CV events and all-cause mortality, providing information independent of established clinical risk factors and cardiorenal biomarkers. A potential sex difference in these findings deserves further study.

Association of Fibroblast Growth Factor 23 With Risk of Incident Coronary Heart Disease in Community-Living Adults

Importance

Higher circulating fibroblast growth factor 23 (FGF23) concentrations are associated with cardiovascular disease events linked to heart failure, but associations of FGF23 with coronary heart disease (CHD) have been less consistent.

Objective

To determine the association of plasma FGF23 concentrations with incident CHD and whether this association differs by race, sex, or chronic kidney disease status.

Design, Setting, and Participants

We examined the association of FGF23 concentrations with incident CHD risk within the Reasons for Geographic and Racial Differences in Stroke study, a prospective cohort of black and white adults 45 years and older enrolled between January 2003 and October 2007 with follow-up through December 31, 2011. Using a case-cohort design, we measured FGF23 concentrations in 829 participants who developed incident CHD and in 812 participants randomly selected from the Reasons for Geographic and Racial Differences in Stroke study cohort (cohort random sample). To account for the stratified sampling design, the cohort random sample was weighted back to the original cohort overall (n = 22 127). Cox proportional hazards models were used to examine the association of FGF23 concentration with incident CHD, adjusting for CHD risk factors and kidney function. In prespecified analyses, we examined whether race, sex, or chronic kidney disease modified the association of FGF23 concentration with incident CHD.

Exposures

Plasma C-terminal FGF23 concentrations.

Main Outcomes and Measures

Investigator-adjudicated incident CHD events.

Results

Of the 22 127 participants in the weighted cohort random sample, 13 059 (58.9%) were female and 9435 (42.6%) were black, and the mean age was 64.3 (95% CI, 63.7-64.9) years. Greater age, lower estimated glomerular filtration rate, higher urine albumin to creatinine ratio, and female sex were associated with higher FGF23 concentration at baseline. In multivariable models adjusted for established CHD risk factors and kidney function, higher FGF23 concentrations were associated with greater risk of CHD (hazard ratio [HR] comparing fourth with first quartile, 2.15; 95% CI, 1.35-3.42). The magnitude and strength of these associations differed by sex. However, these differences were no longer observed when adjusting for hormone therapy in women (men: HR comparing fourth with first quartile, 2.40; 95% CI, 1.30-4.42; women: HR comparing fourth with first quartile, 2.34; 95% CI, 1.04-5.27) or when using sex-specific FGF23 quartiles (men: HR comparing fourth with first quartile, 2.65; 95% CI, 1.43-4.90; women: HR comparing fourth with first quartile, 2.26; 95% CI, 1.02-5.03).

Conclusions and Relevance

Higher FGF23 concentrations were associated with greater risk of CHD. Heterogeneity in the association by sex may be caused by differences in the distribution of plasma FGF23 concentrations or the use of hormone therapy in men vs women.

Influence of gender and age on haemodialysis practices: a European multicentre analysis

Background

Women of all ages and elderly patients of both genders comprise an increasing proportion of the haemodialysis population. Worldwide, significant differences in practice patterns and treatment results exist between genders and among younger versus older patients. Although efforts to mitigate sex-based differences have been attempted, significant disparities still exist.

Methods

This retrospective cohort study included all 1247 prevalent haemodialysis patients in DaVita units in Portugal (five dialysis centres, n = 730) and Poland (seven centres, n = 517). Demographic data, dialysis practice patterns, vascular access prevalence and the achievement of a variety of Kidney Disease: Improving Global Outcomes (KDIGO) treatment targets were evaluated in relation to gender and age groups.

Results

Body weight and the prescribed dialysis blood flow rate were lower in women (P < 0.001), whereas treated blood volume per kilogram per session was higher (P < 0.01), resulting in higher single-pool Kt/V in women than in men (P < 0.001). Haemoglobin was significantly higher in men (P = 0.01), but the proportion of patients within target range (10–12 g/dL) was similar. Men more often had an arteriovenous fistula than women (80% versus 73%; P < 0.01) with a similar percentage of central venous catheters. There were no gender-specific differences in terms of dialysis adequacy, anaemia parameters or mineral and bone disorder parameters, or in the attainment of KDIGO targets between women and men >80 years of age.

Conclusions

This large, multicentre real-world analysis indicates that haemodialysis practices and treatment targets are similar for women and men, including the most elderly, in DaVita haemodialysis clinics in Europe.

Electrolyte imbalances in an unselected population in an emergency department: A retrospective cohort study

BACKGROUND

Although electrolyte imbalances (EIs) are common in the emergency department (ED), few studies have examined the occurrence of such conditions in an unselected population.

OBJECTIVES

To investigate the frequency of EI among adult patients who present to the ED, with regards to type and severity, and the association with age and sex of the patient, hospital length of stay (LOS), readmission, and mortality.

METHODS

A retrospective cohort study. All patients ≥18 years referred for any reason to the ED between January 1, 2010, and December 31, 2015, who had measured blood electrolytes were included. In total, 62 991 visits involving 31 966 patients were registered.

RESULTS

EIs were mostly mild, and the most common EI was hyponatremia (glucose-corrected) (24.6%). Patients with increasing severity of EI had longer LOS compared with patients with normal electrolyte measurements. Among all admitted patients, there were 12928 (20.5%) readmissions within 30 days from discharge during the study period. Hyponatremia (glucose-corrected) was associated with readmission, with an adjusted odds ratio (OR) of 1.25 (95% CI, 1.18-1.32). Hypomagnesemia and hypocalcemia (albumin-corrected) were also associated with readmission, with ORs of 1.25 (95% CI, 1.07-1.45) and 1.22 (95% CI, 1.02-1.46), respectively. Dysnatremia, dyskalemia, hypercalcemia, hypermagnesemia, and hyperphosphatemia were associated with increased in-hospital mortality, whereas all EIs except hypophosphatemia were associated with increased 30-day and 1-year mortality.

CONCLUSIONS

EIs were common and increasing severity of EIs was associated with longer LOS and increased in-hospital, 30-days and 1-year mortality. EI monitoring is crucial for newly admitted patients, and up-to-date training in EI diagnosis and treatment is essential for ED physicians.

The relationship and threshold of serum phosphate with regard to the 28-day mortality risk in sepsis patients undergoing continuous renal replacement therapy

Objective

To investigate the association between serum phosphate levels and the risk of 28-day mortality in critically-ill patients with septic acute kidney injury (AKI) undergoing continuous renal replacement therapy (CRRT).

Methods

This retrospective cohort study analysed data from critically-ill patients with septic AKI who underwent CRRT between January 2009 and September 2016. Demographic, clinical and routine biochemical data were retrieved from a database and analysed to identify risk factors for 28-day mortality.

Results

A total of 796 patients were included in the analyses. Multivariate regression analyses showed that phosphate (0 h), phosphate (24 h) and delta phosphate were associated with the 28-day mortality in patients with septic AKI undergoing CRRT. The adjusted odds ratios (95% confidence interval) were 1.12 (1.03, 1.22), 1.22 (1.14, 1.30) and 1.12 (1.04, 1.20) for phosphate (0 h), phosphate (24 h) and delta phosphate, respectively. Curve fitting and threshold analyses showed that when phosphate (0 h) was between 5.6 mg/dl and 8.7 mg/dl, phosphate (24 h) was >3.8 mg/dl and delta phosphate was >–1, the 28-day mortality risk increased significantly.

Conclusion

In patients with septic AKI undergoing CRRT, serum phosphate level was associated with the prognosis of patients in terms of 28-day mortality.

Accelerated ageing and renal dysfunction links lower socioeconomic status and dietary phosphate intake

BACKGROUND

We have sought to explore the impact of dietary Pi intake on human age related health in the pSoBid cohort (n=666) to explain the disparity between health and deprivation status in this cohort. As hyperphosphataemia is a driver of accelerated ageing in rodent models of progeria we tested whether variation in Pi levels in man associate with measures of biological ageing and health.

RESULTS

We observed significant relationships between serum Pi levels and markers of biological age (telomere length (p=0.040) and DNA methylation content (p=0.028), gender and chronological age (p=0.032). When analyses were adjusted for socio-economic status and nutritional factors, associations were observed between accelerated biological ageing (telomere length, genomic methylation content) and dietary derived Pi levels among the most deprived males, directly related to the frequency of red meat consumption.

CONCLUSIONS

Accelerated ageing is associated with high serum Pi levels and frequency of red meat consumption. Our data provide evidence for a mechanistic link between high intake of Pi and age-related morbidities tied to socio-economic status.

Outcomes associated to serum phosphate levels in patients with suspected acute coronary syndrome

BACKGROUND

We investigated the association between phosphate and the risk of adverse clinical outcomes in patients with manifest cardiovascular disease (CVD).

METHODS

Observational study of patients hospitalized during 2006-2011 in Stockholm, Sweden, because of suspected acute coronary syndrome (ACS). The exposure was serum phosphate during the hospitalization. We modeled the association between phosphate and in-hospital death or in-hospital events (composite of myocardial infarction, cardiogenic shock, resuscitated cardiac arrest, atrial fibrillation, or atrioventricular block) as well as the one-year post-discharge risk of death or cardiovascular event (composite of myocardial re-infarction, heart failure and stroke). Confounders included demographics, comorbidities, kidney function, diagnoses, in-hospital procedures and therapies.

RESULTS

Included were 2547 patients (68% men, mean age 67±14years) with median phosphate of 1.10 (range 0.14-4.20) mmol/L. During hospitalization, 198 patients died and 328 suffered an adverse event. Within one year post-discharge, further 381 deaths and 632 CVD events occurred. The associations of phosphate with mortality and CVD were J-shaped, with highest risk magnitudes at higher phosphate levels. For instance, compared to patients in the 50th percentile of phosphate distribution, those above the 75th percentile (1.3mmol/L, normal range) had significantly higher odds for in-hospital death [odds ratio 1.36, 95% confidence interval (CI) (1.08-1.71)] and of CVD post-discharge [sub-hazard ratios 1.17 (1.03-1.33)].

CONCLUSIONS

In patients with suspected ACS, both higher and lower phosphate levels associated with increased risk of adverse outcomes during the index hospitalization and within one year post-discharge. The risk association was present already within normal-range serum phosphate values.

Associations between serum calcium, phosphorus and mortality among patients with coronary heart disease

PURPOSE

Serum calcium and phosphorus abnormalities are associated with cardiovascular disorders in general population, but evidence among patients with established coronary heart disease (CHD) is limited and controversial. This study aimed to investigate the associations of baseline serum calcium and phosphorus levels with long-term mortality risk among patients with CHD.

METHODS

We conducted a prospective cohort study among 3187 patients with CHD from October 2008 and December 2011 in China. Cox proportional hazards model was used to assess the associations of serum calcium and phosphorus at baseline with the risk of death.

RESULTS

During follow-up (mean, 4.9 years), 295 patients died, 193 of which resulted from cardiovascular causes. Multivariable-adjusted hazard ratios (HR) for each 1 mmol/L increase in serum calcium at baseline were 0.27 (95% confidence interval (CI) 0.14-0.51) for all-cause mortality and 0.26 (95% CI 0.12-0.54) for cardiovascular mortality. Patients in the highest compared to the lowest quartile of serum calcium were at lower risk of all-cause mortality (HR, 95% CI 0.57, 0.40-0.82) and cardiovascular mortality (0.50, 0.32-0.79) (both P _trend < 0.001). This inverse association between serum calcium and the risk of mortality did not change when participants were stratified by sex, age groups, level of overweight, types of CHD, and history of diabetes. We also observed a graded positive association between baseline serum phosphorus and the risks of mortality.

CONCLUSIONS

The present study is the first to report that lower serum calcium at baseline is associated with an increased risk of all-cause and cardiovascular mortality in a Chinese coronary heart disease cohort. Further studies are required to investigate the causal relationship and actual mechanisms.

Sex and gender differences in chronic kidney disease: progression to end-stage renal disease and haemodialysis

Sex and gender differences are of fundamental importance in most diseases, including chronic kidney disease (CKD). Men and women with CKD differ with regard to the underlying pathophysiology of the disease and its complications, present different symptoms and signs, respond differently to therapy and tolerate/cope with the disease differently. Yet an approach using gender in the prevention and treatment of CKD, implementation of clinical practice guidelines and in research has been largely neglected. The present review highlights some sex- and gender-specific evidence in the field of CKD, starting with a critical appraisal of the lack of inclusion of women in randomized clinical trials in nephrology, and thereafter revisits sex/gender differences in kidney pathophysiology, kidney disease progression, outcomes and management of haemodialysis care. In each case we critically consider whether apparent discrepancies are likely to be explained by biological or psycho-socioeconomic factors. In some cases (a few), these findings have resulted in the discovery of disease pathways and/or therapeutic opportunities for improvement. In most cases, they have been reported as merely anecdotal findings. The aim of the present review is to expose some of the stimulating hypotheses arising from these observations as a preamble for stricter approaches using gender for the prevention and treatment of CKD and its complications.

Serum phosphorus levels and risk of incident dementia

Higher serum phosphorous is associated with cerebral small vessel disease, an important driver of cognitive decline and dementia. Whether serum phosphorous, a potentially modifiable parameter, associates with risk of incident dementia is not known. We aimed to examine the association between serum phosphorous and risk of incident dementia and to determine if the association is modified by age. We used the United States Department of Veterans Affairs national databases to build a longitudinal observational cohort of US veterans without prior history of dementia and with at least one outpatient serum phosphorus between October 2008 and September 2010 and followed them until September 2014. Serum phosphorus was categorized into quintiles: ≤2.9, >2.9 to ≤3.2, >3.2 to ≤3.5, >3.5 to ≤3.9, >3.9 mg/dL. There were 744,235 participants in the overall cohort. Over a median follow-up of 5.07 years (Interquartile range [IQR]: 4.28, 5.63), adjusted Cox models show that compared to quintile 2, the risk of incident dementia was increased in quintile 4 (Hazard Ratio [HR] = 1.05; CI = 1.01–1.10) and quintile 5 (HR = 1.14; CI = 1.09–1.20). In cohort participants ≤60 years old, the risk of incident dementia was increased in quintile 4 (HR = 1.29; CI = 1.12–1.49) and 5 (HR = 1.45; CI = 1.26–1.68). In participants > 60 years old, the risk was not significant in quintile 4, and was attenuated in quintile 5 (HR = 1.10; CI = 1.05–1.16). Formal interaction analyses showed that the association between phosphorous and dementia was more pronounced in those younger than 60, and attenuated in those older than 60 (P for interaction was 0.004 and <0.0001 in quintiles 4 and 5; respectively). We conclude that higher serum phosphorous is associated with increased risk of incident dementia. This association is stronger in younger cohort participants. The identification of serum phosphorous as a risk factor for incident dementia has public health relevance and might inform the design and implementation of risk reduction strategies.

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.