Hyperphosphatemia is associated with anemia in adults without chronic kidney disease: results from the National Health and Nutrition Examination Survey (NHANES): 2005-2010

Contribution of vitamin B 6 deficiency to anemia in children on regular hemodialysis

BACKGROUND

Anemia is prevalent among pediatric patients diagnosed with end-stage kidney disease (ESKD). In addition, erythropoiesis-stimulating agents (ESA) and iron supplementation are considered the cornerstones in the management of anemia. However, a significant proportion of patients remain anemic. Vitamin B6 plays a vital role in the biosynthesis of heme and may be deficient in children with chronic kidney disease (CKD), particularly those on regular hemodialysis (HD). We aimed to evaluate serum vitamin B6 concentration in those children and determine its correlation with anemia indices.

METHODS

The current cross-sectional study included 39 children on regular HD and 43 healthy controls. Clinical data were collected, including anthropometric measurements, blood pressure, iron, and erythropoietin therapy. Laboratory investigations included hemoglobin (Hb) indices, iron profile, and vitamin B6 level.

RESULTS

The median Hb level in our cohort was 10.5 g/dL, and nine patients had Hb levels at or above the target Hb of 11 g/dl. They had a median Serum Vitamin B6 concentration of 28.2 ng/ml (IQR = 22.8-52.9) compared to a median of 27.5 ng/ml(IQR = 20-34) in controls, with no substantial differences between both groups. There was no statistically significant correlation between vitamin B6 and Hb levels or erythropoietin dose.

CONCLUSION

It is evident that the majority of our patients did not meet the desired threshold for anemia control. However, it is noteworthy that the average hemoglobin (Hb) level approached the intended target. The incidence of Vitamin B6 deficiency was not found to be statistically significant within our study population. Therefore, we could not establish a correlation between vitamin B6 deficiency and anemia in children on HD.

Phosphorus-independent role of FGF23 in erythropoiesis and iron homeostasis

A number of studies have reported an association between phosphorus, red blood cell (RBC) production, and iron metabolism. However, it is difficult to distinguish whether the effect of phosphorus is direct or through the actions of FGF23, and it is not clear whether phosphorus is positively or negatively associated with RBC production. In the present study, we investigated the effects of a) increased phosphorus load and b) phosphorus deficiency on erythropoiesis and iron metabolism in association with FGF23. Mice were fed either a 1.2% or 1.65% phosphorus diet and compared to mice fed a control diet containing 0.6% of phosphorus. Moreover, we used two mouse models of hypophosphatemia-induced either by dietary intervention in the form of a low phosphorus (LP) diet (0.02% of Pi) or genetically in a mouse model of X-linked hypophosphatemia (XLH)-that had opposite FGF23 levels. Phosphorus supplementation appropriately increased FGF23 levels leading to excretion of excess phosphorus and normalization of serum phosphorus levels. We also found that a phosphorus-rich diet results in inflammation-induced hypoferremia associated with reduced iron export leading to tissue iron overload. Moreover, high phosphorus intake results in ineffective erythropoiesis caused by decreased production (decreased RBCs, hemoglobin, hematocrit, and erythroid progenitors in the bone marrow) and increased destruction of RBCs, leading to anemia despite increased EPO secretion. These complications occur through the actions of elevated FGF23 in the presence of normophosphatemia. Our data also show that LP diet induces a decrease in the serum concentrations of phosphorus and FGF23, resulting in increased RBC counts, hemoglobin concentration, and hematocrit compared to mice fed normal diet. Moreover, serum iron and transferrin saturation were increased and positively correlated with serum ferritin, liver ferritin protein and mRNA expression in mice fed LP diet. However, hyp mice, the murine model of XLH, exhibit hypophosphatemia and high serum FGF23 levels, along with low number of circulating RBCs, hemoglobin, and hematocrit compared to wild-type mice. In the bone marrow, hyp mice showed reduced number of erythroid progenitors and formed significantly less BFU-E colonies compared to control mice. Serum iron levels and transferrin saturation were also decreased in hyp mice in comparison to control mice. Taken together, our data show that FGF23 acts independent of phosphorus levels to regulate erythropoiesis and iron homeostasis.

Influence of hydroxyurea on tubular phosphate handling in sickle cell nephropathy

OBJECTIVE

This study aims to evaluate the markers of tubular phosphate handling in adults with sickle cell anemia (SCA) and the influence of hydroxyurea (HU), the degree of anemia and Hb F concentration on these markers.

METHODS

Eighty-eight steady state SCA patients in outpatient follow-up in Fortaleza, Ceara, Brazil and 31 healthy individuals were included in this study. Vitamin D (25OHD) was measured by enzyme-bound fluorescence assay, intact parathyroid hormone (iPTH) by electrochemiluminescence, and serum and urinary phosphate and creatinine by colorimetric methods. Details of Hb F and HU use were obtained from clinical records. Tubular reabsorption of phosphate (TRP) and maximum tubular reabsorption of phosphate (MTRP) were calculated. SCA patients were stratified according to the use of HU, degree of anemia and percentage of Hb F. The significance level was set for p-values <0.05.

RESULTS

Compared to controls the 25OHD level (25 ± 11 vs. 30 ± 9 pg/mL) was lower in SCA, while serum phosphate and MTRP were higher (3.86 ± 0.94 vs. 3.46 ± 0.72 and 3.6 ± 1.21 vs. 3.21 ± 0.53, respectively). There was no significant difference in iPTH, TRP and phosphaturia. Serum phosphate showed correlation with TRP (r = 0.32; p-value = 0.008) and MTRP (r = 0.9; p-value <0.001) in SCA. Patients taking HU, especially those with Hb F >10 % presented reduced serum phosphate levels, and TRP and MTRP rates. Those with mild anemia presented reduced serum phosphate levels and MTRP rates.

CONCLUSION

Serum phosphate levels and renal phosphate reabsorption rate were increased in SCA. HU use, high Hb F concentration and total Hb were associated with better control of tubular phosphate handling markers.

Reversible and Turn-On Fluorescence Detection of Phosphate in Aqueous Solution and Living Cell Imaging by Supramolecular Metallacycles with AIE-Active Ligands

Luminescent supramolecular metallacycles have attracted great interest as a new promising class of sensing substrates. In this work, two tetraphenylethene (TPE)-based diimidazole and dipyrazole ligands with the aggregation-induced emission (AIE) feature were designed for the construction of supramolecular tetragonal metallacycles 1-4 with two 90° mononuclear [(bpy)M]2+ or dinuclear [(bpy)2M2]4+ acceptors (bpy = 2,2'-dipyridine; M = Pd, Pt), in which the fluorescence can be quenched to an "off" state due to the ligand-to-metal charge transfer (LMCT). Metallacycle 1 was utilized as a fluorescence sensor for phosphate (PO43-) detection in aqueous solution by means of disassembly, leading to the release of the ligand. Additionally, the metallacycle can be regenerated through self-assembly via the introduction of Pd(II) acceptors. PO43- was detected using TPE-based metallacycles over a wide concentration range, with a detection limit as low as 2.1 × 10-8 M. Furthermore, sensor 1 also presented the semiquantitative visual detection ability for PO43- in the test paper mode via fluorescence changes. The aforementioned studies not only enhance the current research on fluorescent materials but also offer a strategy for the creation of stimuli-responsive supramolecular coordination complexes.

Physiopathology of Phosphate Disorders

Intracellular phosphate is critical for cellular processes such as signaling, nucleic acid synthesis, and membrane function. Extracellular phosphate (Pi) is an important component of the skeleton. Normal levels of serum phosphate are maintained by the coordinated actions of 1,25-dihydroxyvitamin D3, parathyroid hormone and fibroblast growth factor-23, which intersect in the proximal tubule to control the reabsorption of phosphate via the sodium-phosphate cotransporters Npt2a and Npt2c. Furthermore, 1,25-dihydroxyvitamin D3 participates in the regulation of dietary phosphate absorption in the small intestine. Clinical manifestations associated with abnormal serum phosphate levels are common and occur as a result of genetic or acquired conditions affecting phosphate homeostasis. For example, chronic hypophosphatemia leads to osteomalacia in adults and rickets in children. Acute severe hypophosphatemia can affect multiple organs leading to rhabdomyolysis, respiratory dysfunction, and hemolysis. Patients with impaired kidney function, such as those with advanced CKD, have high prevalence of hyperphosphatemia, with approximately two-thirds of patients on chronic hemodialysis in the United States having serum phosphate levels above the recommended goal of 5.5 mg/dL, a cutoff associated with excess risk of cardiovascular complications. Furthermore, patients with advanced kidney disease and hyperphosphatemia (>6.5 mg/dL) have almost one-third excess risk of death than those with phosphate levels between 2.4 and 6.5 mg/dL. Given the complex mechanisms that regulate phosphate levels, the interventions to treat the various diseases associated with hypophosphatemia or hyperphosphatemia rely on the understanding of the underlying pathobiological mechanisms governing each patient condition.

Iron deficiency, but not anemia, is identified in naturally occurring obesity and insulin resistance in male nonhuman primates

OBJECTIVES

To understand the development of iron deficiency in obesity and its long-term impact on the profile of anemia in spontaneously obese nonhuman primates.

METHODS

The study included 69 adult male nonhuman primates, (NHPs, Macaca mulatta, rhesus monkeys), ranging from normal to obese, and type 2 diabetes (T2D) as defined for humans.

RESULTS

Iron deficiency was present in 31.9% and mild anemia in 13% of the rhesus monkey in the colony. Serum iron levels were significantly lower in obese (p < .01) and T2D (p < .01)) compared with normal NHP. Obese NHPs also had significantly higher hemoglobin (p < .05), and red blood cell count (p < .05) than normal weight NHPs, thus not related to anemia.

CONCLUSIONS

Iron deficiency with increased hemoglobin and red blood cells was significantly associated with increased adiposity, insulin resistance, and diabetes. Iron deficiency does not cause and is not related to anemia in obese and T2D NHPs.

Hyperphosphatemia increases inflammation to exacerbate anemia and skeletal muscle wasting independently of FGF23-FGFR4 signaling

Elevations in plasma phosphate concentrations (hyperphosphatemia) occur in chronic kidney disease (CKD), in certain genetic disorders, and following the intake of a phosphate-rich diet. Whether hyperphosphatemia and/or associated changes in metabolic regulators, including elevations of fibroblast growth factor 23 (FGF23) directly contribute to specific complications of CKD is uncertain. Here, we report that similar to patients with CKD, mice with adenine-induced CKD develop inflammation, anemia, and skeletal muscle wasting. These complications are also observed in mice fed high phosphate diet even without CKD. Ablation of pathologic FGF23-FGFR4 signaling did not protect mice on an increased phosphate diet or mice with adenine-induced CKD from these sequelae. However, low phosphate diet ameliorated anemia and skeletal muscle wasting in a genetic mouse model of CKD. Our mechanistic in vitro studies indicate that phosphate elevations induce inflammatory signaling and increase hepcidin expression in hepatocytes, a potential causative link between hyperphosphatemia, anemia, and skeletal muscle dysfunction. Our study suggests that high phosphate intake, as caused by the consumption of processed food, may have harmful effects irrespective of pre-existing kidney injury, supporting not only the clinical utility of treating hyperphosphatemia in CKD patients but also arguing for limiting phosphate intake in healthy individuals.

ALKBH1 reduces DNA N6-methyladenine to allow for vascular calcification in chronic kidney disease

Vascular calcification is a common complication of chronic kidney disease (CKD), and one of the main risk factors for increased cardiovascular morbidity and mortality in patients with CKD. In this issue of the JCI, Ouyang and Su et al. report that Alkb homolog 1 (ALKBH1), a DNA demethylase, reduced DNA N6-methyladenine (6mA) in vascular smooth muscle cells (VSMCs) and leukocytes, thus leading to aortic arch calcification in the patients with CKD. During the progression of vascular calcification, increased ALKBH1 expression was linked to decreased 6mA levels, findings that the authors noted in both patients with CKD and CKD mouse models. The kidney and vascular disease risk factor soluble urokinase receptor (suPAR) was also elevated in the plasma. Notably, lower 6mA levels induced BMP2-mediated osteogenic reprogramming in the VSMCs. These findings present a function of ALKBH1 in vascular calcification and provide a framework for therapeutic strategies.

Sugar sweetened beverage consumption is positively associated with Klotho levels at two years of age in LatinX youth

Background

Klotho is an anti-aging protein mainly expressed in the kidneys with a smaller amount expressed in adipose tissue. Klotho effects include roles in reducing oxidative stress, insulin signaling, adipogenesis and glucose metabolism. Few studies have investigated the role of dietary factors such as sugar sweetened beverages (SSBs) on serum α-klotho levels in young children.

Methods

Data was collected from 60 low-income Latina pregnant women and their infants in San Francisco from birth until 2 years of life and examined for associations between dietary factors and child secreted α-klotho protein levels at 2 years.

Results

Mean α-klotho levels were 1782.96 ± 874.56 pg/mL at 2 years of age. Any consumption of SSBs was independently associated with increased α-klotho levels (Beta = 682.79, 95%CI 67.50, 1298.09; p = 0.03). Household income ranging from $25,000 to $50,000 was also correlated to higher levels of α-klotho in children compared with lower income levels (<$25,000) (Beta = 1613.35, 95%CI 527.37, 2699.33; p = 0.005).

Conclusions

The positive association between SSB intake and α-klotho levels at 2 years may reflect higher phosphate levels consistent with SSB intake. Higher socioeconomic status may be a proxy for reduced stress exposure in children, also associated with higher α-klotho levels. Future studies should evaluate the early impact of exposures to SSBs, stress and accelerated aging in children.

Iron-Enriched Nutritional Supplements for the 2030 Pharmacy Shelves

Iron deficiency (ID) affects people of all ages in many countries. Due to intestinal blood loss and reduced iron absorption, ID is a threat to IBD patients, women, and children the most. Current therapies can efficiently recover normal serum transferrin saturation and hemoglobin concentration but may cause several side effects, including intestinal inflammation. ID patients may benefit from innovative nutritional supplements that may satisfy iron needs without side effects. There is a growing interest in new iron-rich superfoods, like algae and mushrooms, which combine antioxidant and anti-inflammatory properties with iron richness.

Characterization of an active ingredient made of nanoscale iron(oxyhydr)oxide for the treatment of hyperphosphatemia

Kidney disease is one of the main non-communicable diseases. Every year millions of people worldwide die from kidney dysfunction. One cause is disturbances in the mineral metabolism, such as abnormally high phosphate concentrations in the blood, medically referred to as hyperphosphatemia. A new active ingredient based on nanoscale iron(oxyhydr)oxide with particle sizes below 3 nm surrounded by an organic coating has been developed for a more effective treatment. The examination of the structural properties of these particles within this study promises to gain further insights into this improved effectiveness. More than half of the active ingredient consists of organic substances, the rest is mostly iron(oxyhydr)oxide. Analyzes by transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and dynamic light scattering (DLS) show that the organic molecules act as stabilizers and lead to ultrasmall iron(oxyhydr)oxide cores with a size of 1.0–2.8 nm. The nanoparticles coated with the organic molecules have an average size of 11.7 nm. At 4.2 K, the nanoparticles display a magnetic hyperfine field of 45.5 T in the Mössbauer spectrum, which is unusually low for iron(oxyhydr)oxide. The material is also not ferrimagnetic. Combining these results and taking into account the composition of the nanoparticles, we identify low crystalline ferrihydrite as the most likely phase in the iron(oxyhydr)oxide nuclei. At the same time, we want to emphasize that a final identification of the crystal structure in iron(oxyhydr)oxides can be impeded by ultrasmall particle sizes. In summary, by a combinatorial characterization, we are able to observe extraordinary properties of the ultrasmall nanomaterial, which is the basis for the investigation of the high phosphate-binding efficacy of this active ingredient.

The combination of different analytical methods, supported by TEM, DLS, SAXS, Mössbauer spectroscopy, and SQUID, allows more accurate characterization of a new nanoscale active ingredient based on iron(oxyhydr)oxide against hyperphosphatemia.

Examining the association between serum phosphate levels and leukocyte telomere length

Accelerated telomere attrition is related to various diseases, and multiple factors have been reported to influence telomere length. However, little attention has focused on the relationship between serum phosphate levels and mean telomere length. The purpose of this study was to explore the relationship between serum phosphate levels and mean telomere length in the US general population. A total of 7,817 participants from the 1999–2002 NHANES were included. The association between serum phosphate levels and mean telomere length was investigated using regression models. A remarkably positive relationship between serum phosphate levels and mean telomere length emerged after adjustments were made for covariates. The adjusted β coefficient of serum phosphate levels for mean telomere length was 0.038 (95% confidence intervals (CIs), 0.022 to 0.095, p = 0.002). A longer telomere length was observed in participants with serum phosphate levels in the highest quartiles, and a dose-dependent association was observed. Our study demonstrated that higher quartiles of phosphate had a remarkable correlation with longer telomere length.

A review of select minerals influencing the haematopoietic process

Micronutrients are indispensable for adequate metabolism, such as biochemical function and cell production. The production of blood cells is named haematopoiesis and this process is highly consuming due to the rapid turnover of the haematopoietic system and consequent demand for nutrients. It is well established that micronutrients are relevant to blood cell production, although some of the mechanisms of how micronutrients modulate haematopoiesis remain unknown. The aim of the present review is to summarise the effect of Fe, Mn, Ca, Mg, Na, K, Co, iodine, P, Se, Cu, Li and Zn on haematopoiesis. This review deals specifically with the physiological requirements of selected micronutrients to haematopoiesis, showing various studies related to the physiological requirements, deficiency or excess of these minerals on haematopoiesis. The literature selected includes studies in animal models and human subjects. In circumstances where these minerals have not been studied for a given condition, no information was used. All the selected minerals have an important role in haematopoiesis by influencing the quality and quantity of blood cell production. In addition, it is highly recommended that the established nutrition recommendations for these minerals be followed, because cases of excess or deficient mineral intake can affect the haematopoiesis process.

Interaction of Serum Phosphate with Age as Predictors of Cardiovascular Risk Scores in Stable Renal Transplant Recipients

We calculated rate of changes in the cardiovascular risk calculator for renal transplant recipients (CRCRTR) major adverse cardiac events (MACE) in clinically stable renal transplant recipients (RTRs) to identify covariables that associate with fast cardiovascular (CV) risk progression. CRCRTR-MACE scores were calculated on 139 patients in 2011 and 2014. Score changes above and below median changes in scores were labeled fast or slow CV risk progression. Multivariate analysis (MVA) was performed to identify variables significant to percentage changes in scores. Receiver-operating characteristic (ROC) analysis was performed to define sensitivity and specificity of factors significant to fast score progression. Follow-up was 2.61 (2.02-4.47) years. Slow and fast progressions were present in 50.4 and 49.6% of patients, with a median change of 25.8% (- 92.1 to 1,444.7%). MVA showed percentage changes in age and serum phosphate were the only significant variables impacting fast progression in scores. ROC showed 2011 serum phosphate of 1.15 mmol/L to predict fast progression (area under the curve [AUC] of 0.628, p > 0.0126). Age older than 45 years combined with 2011 serum phosphate above 1.15 mmol/L had a significant AUC of 0.781, p < 0.0010 interleukin (IL)-1A and IL-28A were significant associates with serum phosphate above 1.1 mmol/L in the MVA. Changes in CV risk in RTR over time are highly variable. Serum phosphate, even within upper normal levels, predicts worsening of CV risk scores in stable RTR.

Covariation between plasma phosphate and daytime cortisol in early Parkinson's disease

BACKGROUND

Disturbed phosphate homeostasis in early Parkinson's disease (PD) may originate from a stress-related condition and nutritional status among other risk factors, age, and gender.

METHODS

Risk of malnutrition using Mini-nutritional assessment (MNA score) and plasma levels of protein markers and daytime cortisol at the time of diagnosis in PD (n = 75) were compared with a control group (n = 24). Cognition was assessed using the Mini-Mental State Examination (MMSE score) and motor function using Unified Parkinson's Disease Rating Scale (UPDRS-part III scale).

RESULTS

The patients with PD had significantly lower MNA score than controls which correlated with plasma phosphate levels. The logistic regression revealed that increasing MNA protected from low plasma phosphate, final score (OR = 0.399; 95% CI = 0.196-0.816; p = .012) and total score (OR = 0.656; 95% CI = 0.422-1.018; p = .060). Phosphate correlated with albumin (r = .315; p < .006), transferrin (r = .331; p < .004) and cortisol (r = -0.355; p < .002) confirmed by logistic regressions. Increasing albumin protects from low phosphate after adjusting in logistic regression (OR = 0.806; 95% CI = 0.682-0.952; p = .011) and after including variables from Table 1 in backwards elimination, final step (OR = 0.800; 95% CI = 0.660-0.969; p = .022). MNA total score and cortisol correlated inversely, confirmed in logistic regression for MNA total score (OR = 0.786; 95% CI = 0.627-0.985; p = .037) and for MNA initial score (OR = 0.650; 95% CI = 0.453-0.930; p = .020).

CONCLUSION

This study highlights the importance of phosphate for optimal nutritional status by association with MNA score and albumin in plasma. An inverse relationship between phosphate and cortisol indicate, in addition, that low phosphate levels may affect cognition and motor function in PD.

Association between Vitamin D Deficiency and Anemia in Patients with End-Stage Renal Disease: A Cross-Sectional Study

PURPOSE

Despite new treatment strategies, anemia remains the most prevalent complication in patients with end-stage renal disease (ESRD). We investigated whether 25-hydroxyvitamin D [25(OH)D3] deficiency was associated with anemia in ESRD patients.

MATERIALS AND METHODS

We reviewed the medical records of 410 ESRD patients who had undergone renal transplantation (RTx) at Yonsei University Health System and who had 25(OH)D3 levels measured at the time of RTx. Patients were divided into two groups based on baseline 25(OH)D3 concentrations: group 1, 25(OH)D3 levels <10 ng/mL; and group 2, 25(OH)D3 levels ≥10 ng/mL.

RESULTS

Using multivariate regression models, 25(OH)D3, age, and erythrocyte-stimulating agent (ESA) dose were found to be significantly associated with hemoglobin (Hb) levels [25(OH)D3: β=0.263, p<0.001; age: β=0.122, p=0.010; ESA dose: β=-0.069, p=0.005]. In addition, logistic regression analysis revealed that patients in group 1 had a significantly higher risk for developing anemia (Hb level <10 g/dL) compared to group 2 patients, even after adjusting for potential risk factors for anemia (odds ratio=3.857; confidence interval=1.091-13.632; p=0.036).

CONCLUSION

25(OH)D3 deficiency was significantly associated with anemia in patients with ESRD. Randomized controlled trials are needed to determine whether vitamin D supplementation can improve anemia in these patients.

Association of Serum Phosphate Levels and Anemia in Critically Ill Surgical Patients

BACKGROUND

Deranged serum phosphate (Phos) levels are associated with anemia in hospitalized patients, but their relevance to critical illness is unclear. Therefore, our goal was to investigate whether abnormal Phos on admission to the surgical intensive care unit (ICU) is associated with anemia.

MATERIALS AND METHODS

We performed a retrospective analysis of data from an ongoing study of nutrition in critical illness. Serum Phos and hemoglobin levels were obtained at ICU admission. Normal Phos was defined as 2.5-4.0 mg/dL. To investigate the association between Phos and anemia, we performed logistic regression analyses, while controlling for age, sex, race, body mass index, Nutrition Risk Screening score, Deyo-Charlson Comorbidity Index, creatinine, mean corpuscular volume, and serum albumin.

RESULTS

In total, 510 patients comprised the analytic cohort; 62% were anemic, 30% had Phos >4.0 mg/dL, and 14% had levels <2.5 mg/dL. Logistic regression analysis demonstrated each unit increment in Phos was associated with a 25% higher likelihood of anemia (odds ratio [OR], 1.25; 95% confidence interval [CI], 1.04-1.50). Moreover, patients with Phos >4.0 mg/dL had a 68% higher likelihood of anemia compared with those with normal levels (OR, 1.68; 95% CI, 1.02-2.80). Patients with Phos <2.5 mg/dL were not more likely to be anemic compared with those with normal levels.

CONCLUSION

Surgical ICU patients with admission Phos >4.0 mg/dL are more likely to be anemic compared with those with normal levels. Our findings support the need for studies to determine whether globally maintaining optimal Phos reduces the likelihood of anemia and whether ideal Phos during acute care hospitalization influences clinical outcomes.

Serum phosphorus and association with anemia among a large diverse population with and without chronic kidney disease

BACKGROUND

We hypothesized that phosphorus has an effect on anemia in both normal kidney function and early chronic kidney disease (CKD). We sought to determine whether higher phosphorus levels are associated with anemia in a large diverse population without CKD and early CKD.

METHODS

This study is a historical population-based study within the Kaiser Permanente Southern California health system (1 January 1998 to 31 December 2013) among individuals aged 18 years and older with estimated glomerular filtration rate >30 mL/min/1.73 m(2) and measurements of serum phosphorus, creatinine and hemoglobin. Individuals were excluded if they had secondary causes of anemia. Odds ratio (OR) estimated for moderate anemia defined as hemoglobin <11 g/dL for both sexes. Mild anemia was defined as <12 g/dL (females) and <13 g/dL (males).

RESULTS

Among 155 974 individuals, 4.1% had moderate anemia and 12.9% had mild anemia. Serum phosphorus levels ≥3.5 mg/dL were associated with both mild and moderate anemia. Moderate anemia OR (95% confidence interval) was 1.16 (1.04-1.29) for every 0.5 mg/dL phosphorus increase and 1.26 (1.07-1.48) in the highest versus middle phosphorus tertile. Additional independent anemia risk factors, including female sex, Asian race, diabetes, low albumin and low iron saturation, were observed, but did not alter the anemia-phosphorus association.

CONCLUSIONS

Higher phosphorus levels were associated with a greater likelihood for anemia in a population with early CKD and normal kidney function. Phosphorus may be a biomarker for anemia and may affect aspects of hematopoiesis.

Hyperphosphatemia Management in Patients with Chronic Kidney Disease

Hyperphosphatemia in chronic kidney disease (CKD) patients is a potentially life altering condition that can lead to cardiovascular calcification, metabolic bone disease (renal osteodystrophy) and the development of secondary hyperparathyroidism (SHPT). It is also associated with increased prevalence of cardiovascular diseases and mortality rates. To effectively manage hyperphosphatemia in CKD patients it is important to not only consider pharmacological and nonpharmacological treatment options but also to understand the underlying physiologic pathways involved in phosphorus homoeostasis. This review will therefore provide both a background into phosphorus homoeostasis and the management of hyperphosphatemia in CKD patients. In addition, it will cover some of the most important reasons for failure to control hyperphosphatemia with emphasis on the effect of the gastric pH on phosphate binders efficiency.