Antihypertensive treatment with hydrochlorothiazide-hydralazine combination aggravates medial vascular calcification in CKD rats with mineral bone disorder

Background

Arterial stiffness and medial vascular calcification, leading to isolated systolic blood pressure (BP), are major cardiovascular risk factors in patients with chronic kidney disease (CKD) and mineral bone disorders (MBD). The impact of BP on MBD-induced medial vascular calcification in CKD remains uncertain. We investigated whether BP reduction improves arterial stiffness and medial vascular calcification in a rat model of CKD-MBD.

Methods

CKD was induced in Wistar rats by subtotal nephrectomy. Then, MBD was generated by a Ca/P-rich diet with calcitriol supplementation to induce medial vascular calcification. Two antihypertensive treatments were evaluated: (1) the angiotensin AT1 receptor antagonist losartan, and (2) the combination of the thiazide diuretic hydrochlorothiazide and the direct vasodilator hydralazine (HCTZ/HY). After 5 weeks, mean BP (MBP), pulse pressure (PP), and pulse wave velocity (PWV) were determined. Vascular calcification was assessed in the thoracic aorta.

Results

While MBP was similar in CKD-MBD and control CKD rats, PP and PWV were increased in CKD-MBD rats. The heightened arterial stiffness in CKD-MBD rats was associated with diffused medial calcification along the thoracic aorta. Although both losartan and HCTZ/HY reduced MBP in CKD-MBD rats, losartan did not affect PP and PWV nor medial vascular calcification, whereas HCTZ/HY, unexpectedly, further increased arterial stiffness and medial vascular calcification.

Conclusion

In the rat model of CKD-MBD, antihypertensive treatment with losartan did not affect arterial stiffness or medial vascular calcification. However, HCTZ/HY treatment aggravated arterial stiffness and vascular calcification despite a similar reduction of MBP, suggesting a blood pressure-independent mechanism for vascular calcification.

Corrigendum: Mineral bone disorder in children with chronic kidney disease: data from the KNOW-Ped CKD (Korean cohort study for outcome in patients with pediatric chronic kidney disease) study

[This corrects the article DOI: 10.3389/fped.2023.994979.].

Mineral bone disorder in children with chronic kidney disease: Data from the KNOW-Ped CKD (Korean cohort study for outcome in patients with pediatric chronic kidney disease) study

BACKGROUND

Children with chronic kidney disease (CKD) are at high risk of mineral bone disorder (MBD), which leads to fractures, growth retardation, and cardiovascular disease. We aimed to comprehensively understand the relationship between renal function and factors related to MBD and evaluate the prevalence and distribution characteristics of MBD, specifically among Korean patients from the KNOW-PedCKD cohort.

METHODS

From the baseline data of the KNOW-PedCKD cohort, we examined the prevalence and distribution of MBD in 431 Korean pediatric CKD patients, including the level of corrected total calcium, serum phosphate, serum alkaline phosphatase, serum intact parathyroid hormone (iPTH), fibroblast growth factor 23 (FGF-23), serum vitamin D, fractional excretion of phosphate (FEP), and bone densitometry Z-scores.

RESULTS

The median serum calcium level remained relatively normal regardless of the CKD stage. The levels of 1,25-dihydroxy vitamin D, urine calcium-to-creatinine ratio, and bone densitometry Z-score significantly decreased with advancing CKD stage, while those of serum phosphate, FGF-23, and FEP significantly increased with CKD stage. The prevalence of hyperphosphatemia (17.4%, 23.7%, and 41.2% from CKD stages 3b, 4, and 5, respectively) and hyperparathyroidism (37.3%, 57.4%, 55.3%, and 52.9% from CKD stages 3a, 3b, 4, and 5, respectively) significantly increased with the CKD stage. Prescriptions of medications, such as calcium supplements (39.1%, 42.1%, 82.4%), phosphate binders (39.1%, 43.4%, 82.4%), and active vitamin D (21.7%, 44.7%, and 64.7%) significantly increased with CKD stage 3b, 4, and 5, respectively.

CONCLUSIONS

The results demonstrated the prevalence and relationship of abnormal mineral metabolism and bone growth according to CKD stage in Korean pediatric CKD patients for the first time.

Vascular calcification maladaptively participates in acute phosphate homeostasis

AIMS

Non-renal extravasation of phosphate from the circulation and transient accumulation into tissues and extracellular fluid is a regulated process of acute phosphate homeostasis that is not well understood. This process is especially relevant in the setting of chronic kidney disease (CKD), where exposure to increased phosphate is prolonged due to inefficient kidney excretion. Furthermore, CKD-associated mineral dysregulation induces pathological accumulation of phosphate causing vascular calcification (VC). Our objective was to determine whether the systemic response to acute phosphate challenges is altered by VC.

METHODS/RESULTS

After bolus phosphate administration, circulating and tissue deposition of this challenge was assessed in two rat models of VC using a radiolabelled phosphate tracer. In an adenine-induced model of CKD (N = 70), animals with VC had a blunted elevation of circulating 33PO4 following oral phosphate administration (p < 0.01), and the discordant deposition could be traced to the calcified arteries (11.4[7.5,13.1]vs.43.0[35.5, 53.7] pmol/ng tissue, p < 0.001). In a non-CKD model of VC, calcification was induced with 0.5ug/kg calcitriol and then withdrawn (N = 24). New phosphate uptake by the calcified vasculature correlated to the pre-existing burden of calcification (r = 38, p < 0.001) and was substantially attenuated in the absence of calcification stimulus (p < 0.01). Phosphate accrual was stimulated by the phosphate challenge, and not present to the same degree during passive disposition of circulating phosphate. Further, the form of phosphate that deposited to the vasculature was predominately amorphous inorganic phosphate, and not that which was bound in matured calciprotein particles.

CONCLUSIONS

In the process of calcification, arteries acutely deposit substantial amorphous phosphate while blunting the elevation in the circulation, thereby altering the systemic disposition of phosphate, and identifying VC as a participatory mineral homeostatic organ. This study demonstrates the negative vascular consequence of acute fluctuations in circulating phosphate, and supports the importance of phosphate bioavailability and diet management in CKD patients as a mediator of cardiovascular risk.

The Influence of Parathyroidectomy on Osteoporotic Fractures in Kidney Transplant Recipients: Results from a Retrospective Single-Center Trial

Kidney transplant (KTx) recipients are a high-risk population for osteoporotic fractures. We herein aim to identify the role of pre-transplant parathyroidectomy (PTX) and other modifiable factors associated with osteoporotic fractures in KTx recipients. We conducted a retrospective study involving 711 adult patients (4608 patient-years) who were transplanted at our center between January 2007 and June 2015. Clinical data were extracted from patients' electronic medical records. Different laboratory and clinical parameters for mineral bone disease (MBD) and osteoporosis, including medication, were evaluated. We chose fracture events unrelated to malignancies or adequate trauma as the primary endpoint. Osteoporotic fractures occurred in 47 (6.6%) patients (median 36.7 months, IQR 45.9) after KTx (fracture incidence of 10 per 1000 person-years). Prior to KTx, subtotal PTX was performed in 116 patients (16.3%, median time 4.2 years before KTx, IQR 5.0). Of the patients with fracture (n = 47), only one (2.2%) patient had previously undergone PTX. After adjusting for the known fracture risk factors MBD and osteoporosis, PTX remained a protective factor against fractures (HR 0.134, CI 0.018-0.991, p = 0.049). We observed a reduced risk for pathological fractures in KTx patients who underwent PTX, independent from elevated parathyroid hormone at the time of KTx or afterwards.

Gender-Related Differences in Chronic Kidney Disease-Associated Vascular Calcification Risk and Potential Risk Mediators: A Scoping Review

Vascular calcification (VC) involves the deposition of calcium apatite in vascular intima or media. Individuals of advanced age, having diabetes mellitus or chronic kidney disease (CKD) are particularly at risk. The pathogenesis of CKD-associated VC evolves considerably. The core driver is the phenotypic change involving vascular wall constituent cells toward manifestations similar to that undergone by osteoblasts. Gender-related differences are observed regarding the expressions of osteogenesis-regulating effectors, and presumably the prevalence/risk of CKD-associated VC exhibits gender-related differences as well. Despite the wealth of data focusing on gender-related differences in the risk of atherosclerosis, few report whether gender modifies the risk of VC, especially CKD-associated cases. We systematically identified studies of CKD-associated VC or its regulators/modifiers reporting data about gender distributions, and extracted results from 167 articles. A significantly higher risk of CKD-associated VC was observed in males among the majority of original investigations. However, substantial heterogeneity exists, since multiple large-scale studies yielded neutral findings. Differences in gender-related VC risk may result from variations in VC assessment methods, the anatomical segments of interest, study sample size, and even the ethnic origins of participants. From a biological perspective, plausible mediators of gender-related VC differences include body composition discrepancies, alterations involving lipid profiles, inflammatory severity, diversities in matrix Gla protein (MGP), soluble Klotho, vitamin D, sclerostin, parathyroid hormone (PTH), fibroblast growth factor-23 (FGF-23), and osteoprotegerin levels. Based on our findings, it may be inappropriate to monotonously assume that male patients with CKD are at risk of VC compared to females, and we should consider more background in context before result interpretation.

The Frailty Phenotype in Hemodialysis Patients and its Association with Biochemical Markers of Mineral Bone Disorder, Inflammation and Nutrition

INTRODUCTION

Frailty is a state of increased vulnerability to physical stressors. It is common in patients with end-stage renal disease (ESRD) who are on hemodialysis (HD).The aim of this study was to analyze the presence of frailty phenotype among HD patients and to evaluate their interrelationship with different biochemical markers.

METHODS

For the frailty assessment the Frailty Phenotype by Fried et al. was used, where frailty was reported if three of the following criteria were met: unintentional weight loss, self-reported exhaustion, weakness, slow walking speed and low physical activity. From 281 HD patients, 126 patients were frail, 58 were pre-frail (two criteria were met) and the rest of the study population were robust (97 patients). BMI was calculated for all patients and venous blood samples were taken to determine laboratory parameters for bone alkaline phosphatase (BAP), phosphate (P), potassium (K), C-reactive protein (CRP) and albumin.

RESULTS

Patients who were on HD longer than 60 months have more characters of frailty. (p=0.019). A statistically significant positive correlations between frailty score and BAP (rho = 0.189; p = 0.001), and CRP (rho = 0.233; p < 0.001) were observed, and significant negative correlations between frailty score and albumin (rho = - 0.218; p < 0.001) and K (rho = - 0.198; p = 0.001).

CONCLUSIONS

The associations of frailty with markers of mineral bone disorder, inflammation and nutrition indicate the importance of these parameters in the indirect assessment of the frailty phenotype in HD patients.

Chronic Kidney Disease-Induced Arterial Media Calcification in Rats Prevented by Tissue Non-Specific Alkaline Phosphatase Substrate Supplementation Rather Than Inhibition of the Enzyme

Patients with chronic kidney disease (CKD) suffer from arterial media calcification and a disturbed bone metabolism. Tissue-nonspecific alkaline phosphatase (TNAP) hydrolyzes the calcification inhibitor pyrophosphate (PPi) into inorganic phosphate (Pi) and thereby stimulates arterial media calcification as well as physiological bone mineralization. This study investigates whether the TNAP inhibitor SBI-425, PPi or the combination of both inhibit arterial media calcification in an 0.75% adenine rat model of CKD. Treatments started with the induction of CKD, including (i) rats with normal renal function (control diet) treated with vehicle and CKD rats treated with either (ii) vehicle, (iii) 10 mg/kg/day SBI-425, (iv) 120 µmol/kg/day PPi and (v) 120 µmol/kg/day PPi and 10 mg/kg/day SBI-425. All CKD groups developed a stable chronic renal failure reflected by hyperphosphatemia, hypocalcemia and high serum creatinine levels. CKD induced arterial media calcification and bone metabolic defects. All treatments, except for SBI-425 alone, blocked CKD-related arterial media calcification. More important, SBI-425 alone and in combination with PPi increased osteoid area pointing to a less efficient bone mineralization. Clearly, potential side effects on bone mineralization will need to be assessed in any clinical trial aimed at modifying the Pi/PPi ratio in CKD patients who already suffer from a compromised bone status.

Mineral Bone Disorders in Kidney Transplantation

Bone disease after kidney transplantation is associated with an increased risk of fractures, morbidity, and mortality. Its pathophysiology is complex, involving multiple contributors including pretransplant bone disease, immunosuppressive medications, and changes in the parathyroid-bone-kidney axis. Risk scores, bone turnover markers, and noninvasive imaging modalities are only able to partially predict the fracture risk in kidney transplant recipients. The optimal management of bone disease after kidney transplantation has not yet been established, with only a limited number of randomized clinical trials evaluating the efficacy of treatment regimens in kidney transplant recipients. This review focuses on the pathophysiology, evaluation, prevention, and treatment of post-kidney transplant mineral and bone disease as guided by recent evidence.

Clinical factors associated with early and persistent hypocalcaemia after parathyroidectomy in patients on dialysis with severe hyperparathyroidism

AIM

Severe hypocalcaemia following parathyroidectomy for secondary or tertiary hyperparathyroidism (SHPT/THPT) is scarcely studied. We aimed to describe and identify risk factors for early and persistent hypocalcaemia after parathyroidectomy.

METHODS

Retrospective pair-matched cohort study. We assessed 87 dialysis patients with SHPT (n = 73) or THPT (n = 14) paired with 146 subjects with primary hyperparathyroidism (PHPT) who underwent parathyroidectomy and were followed for 12 months. Early severe hypocalcaemia was defined as a free Ca ≤0.8 mmol/L [3.2 mg/dl] or corrected Ca ≤1.87 mmol/L [7.5 mg/dl] within 48 h. After parathyroidectomy and persistent hypocalcaemia, as an elemental Ca intake >3.0 g/day to achieve corrected Ca >2 mmol/L [8.0 mg/dl].

RESULTS

Early severe hypocalcaemia occurred in 77% (67/87) versus 6.8% (10/146) of subjects with SHPT/THPT and PHPT, respectively (p < .001). In SHPT/THPT cases, persistent hypocalcaemia occurred in 77% (49/64) and 64% (35/54) after 6 and 12 months of parathyroidectomy, respectively. In PHPT cases, persistent hypocalcaemia occurred in 6.8% (10/146) after 4-12 months of parathyroidectomy. Preoperative serum alkaline phosphatase (ALP) was the only risk factor associated to early severe hypocalcaemia (OR 7.3, 95% C.I. 1.7-10.9, p = .006) and persistent hypocalcaemia (OR 7.1, 95% C.I: 2.1-14.2, p = .011). Subjects with persistently low intact parathormone (iPTH) (<5.3 pmol/L [50 ng/ml]), suggestive of adynamic bone disease) showed higher Ca increases and less oral calcium requirements compared to those who progressively increased iPTH after parathyroidectomy.

CONCLUSION

Early and persistent hypocalcaemia after parathyroidectomy in severe HPT were a common event associated directly to preoperative ALP levels. Subjects with persistently low postoperative iPTH normalized serum Ca more frequently after 1 year of follow up.

Development of a quantitative systems pharmacology model of chronic kidney disease: metabolic bone disorder

Chronic kidney disease mineral bone disorder (CKD-MBD) is a virtually universal complication of kidney diseases, starting early in the course of disease and resulting in devastating clinical consequences ranging from bone fragility to accelerated atherosclerosis and early cardiovascular death. Guidelines for therapeutic goals for CKD-MBD have been published, and achievement of these guidelines is associated with improved survival. However, the incomplete understanding of CKD-MBD and the individual variability in the manifestations of CKD-MBD have made it difficult to achieve these guidelines. We hypothesized that the progression of MBD through all stages of CKD, including end-stage kidney disease, could be represented by a quantitative systems pharmacology/systems biology (QSP) model. To address this hypothesis, we constructed a QSP model of CKD-MBD, building on an open-source model of calcium and phosphorus metabolism. Specifically, we estimated and validated the model using data from 5,496 patients with CKD enrolled in the Chronic Renal Insufficiency Cohort study. Our model accurately predicted changes in markers of mineral metabolism related to progressing CKD. We demonstrated that the incorporation of fibroblast growth factor 23 and the soft tissue compartment is essential for accurate modeling of the changes in calcium, phosphorus, intact parathyroid hormone, and calcitriol in CKD-MBD. We conclude that our systems biology model accurately represents CKD-MBD disease progression and can be used as a test bench for improving therapeutic interventions.

Fractures and their sequelae in non-dialysis-dependent chronic kidney disease: the Stockholm CREAtinine Measurement project

Introduction

People undergoing maintenance dialysis are at high risk for fractures, but less is known about fracture incidence and associated outcomes in earlier stages of chronic kidney disease (CKD).

Methods

We conducted an observational analysis from the Stockholm Creatinine Measurement project, a Swedish health care utilization cohort during 2006–11. We identified all adults with confirmed CKD Stages 3–5 and no documented history of fractures and extracted information on comorbid history, ongoing medication, cardiovascular events and death. We studied incidence rates of fractures (overall and by location), with the estimated glomerular filtration rate (eGFR) as time-dependent exposure. We then studied hazard ratios [HRs and 95% confidence intervals (CIs)] for the events of death and major adverse cardiac events (MACE) using Cox regression with fracture as time-varying exposure.

Results

We identified 68 764 individuals with confirmed CKD (mean age 79 years, 56% women). During a median follow-up of 2.7 years, 9219 fractures occurred, of which 3105 were hip fractures. A more severe CKD stage was associated with a higher risk of fractures, particularly hip fractures: compared with CKD Stage 3a, the adjusted HR was 1.10 (95% CI 1.02–1.19), 1.32 (1.17–1.49) and 2.47 (1.94–3.15) for CKD Stage 3b, 4 and 5, respectively. Spline curves suggested a linear association with fracture risk with an eGFR <30 mL/min/1.73 m². Compared with non-fracture periods, incident fracture was associated with a 4-fold increased mortality within 90 days [HR 4.21 (95% CI 3.95–4.49)]. The risk remained elevated beyond 90 days [HR 1.47 (95% CI 1.40–1.54)] and was stronger after hip fractures. Post-fracture MACE risk was also highest in the first 90 days [HR 4.02 (95% CI 3.73–4.33)], particularly after hip fractures, and persisted beyond 90 days [HR 1.20 (95% CI 1.10–1.30)].

Conclusion

Our findings highlight the commonness of fractures and the increased risk for subsequent adverse outcomes in CKD patients. These results may inform clinical decisions regarding post-fracture clinical surveillance and fracture prevention strategies.

Inhibition of tissue-nonspecific alkaline phosphatase protects against medial arterial calcification and improves survival probability in the CKD-MBD mouse model

Medial arterial calcification (MAC) is a major complication of chronic kidney disease (CKD) and an indicator of poor prognosis. Aortic overexpression of tissue-nonspecific alkaline phosphatase (TNAP) accelerates MAC formation. The present study aimed to assess whether a TNAP inhibitor, SBI-425, protects against MAC and improves survival probability in a CKD-mineral and bone disorder (MBD) mouse model. CKD-MBD mice were divided in three groups: vehicle, SBI-10, and SBI-30. They were fed a 0.2% adenine and 0.8% phosphorus diet from 14 to 20 weeks of age to induce CKD, followed by a high-phosphorus (0.2% adenine and 1.8% phosphorus) diet for another 6 weeks. At 14-20 weeks of age, mice in the SBI-10 and SBI-30 groups were given 10 and 30 mg/kg SBI-425 by gavage once a day, respectively, while vehicle-group mice were given distilled water as vehicle. Control mice were fed a standard chow (0.8% phosphorus) between the ages of 8 and 20 weeks. Computed tomography imaging, histology, and aortic tissue calcium content revealed that, compared to vehicle animals, SBI-425 nearly halted the formation of MAC. Mice in the control, SBI-10 and SBI-30 groups exhibited 100% survival, which was significantly better than vehicle-treated mice (57.1%). Aortic mRNA expression of Alpl, encoding TNAP, as well as plasma and aortic tissue TNAP activity, were suppressed by SBI-425 administration, whereas plasma pyrophosphate increased. We conclude that a TNAP inhibitor successfully protected the vasculature from MAC and improved survival rate in a mouse CKD-MBD model, without causing any adverse effects on normal skeletal formation and residual renal function. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Racial Variations in the Markers of Mineral Bone Disorders in CKD Patients in South Africa

Introduction

Several studies showed that serum intact parathyroid hormone (PTH), phosphate, and vitamin D levels differ across races. These comparative studies were largely carried out between Caucasians and black Americans. However, little is known of the existence of these associations in an African population with chronic kidney disease (CKD).

Methods

This cross-sectional multicenter study involved 293 CKD patients from 3 renal units in Johannesburg, South Africa.

Results

The 293 CKD patients (208 blacks, 85 whites) had an overall mean age of 51.1 ± 13.6 years, and black patients were significantly younger than the white patients (48.4 ± 13.6 years vs. 57.1 ± 15.5 years; P < 0.001). Compared with whites, blacks had higher median intact PTH (498 [range: 37–1084] pg/ml vs. 274 [range: 131–595] pg/ml; P = 0.03), alkaline phosphatase (122 [range: 89–192] U/L vs. 103 [range: 74–144] U/L; p = 0.03), and mean 25 OH vitamin D₃ (26.8 ± 12.7 ng/ml vs. 22.7 ± 12.2 ng/ml, P = 0.01) levels, whereas their median fibroblast growth factor (FGF) level was 23 (100 [range: 34–639] pg/ml vs. 233 [range: 80–1370] pg/ml; P = 0.002), and their mean serum phosphate (1.3 ± 0.5 vs. 1.5 ± 0.5; P = 0.001) levels were significantly lower. In multivariable analyses, black race was independently associated with increased log PTH (β = 0.488, P = 0.01) and decreased log FGF-23 (β = −0.636, P = 0.02). Similarly, blacks had a 3.08 times higher likelihood (95% confidence interval: 1.51–6.30; P = 0.002) of developing severe hyperparathyroidism than whites.

Conclusion

This study highlighted the existence of racial differences in the circulating markers of mineral bone disorders in an African CKD population.

Identification of differentially expressed miRNAs associated with chronic kidney disease-mineral bone disorder

The purpose of this study is to characterize a meta-signature of differentially expressed mRNA in chronic kidney disease (CKD) to predict putative microRNA (miRNA) in CKD-mineral bone disorder (CKD-MBD) and confirm the changes in these genes and miRNA expression under uremic conditions by using a cell culture system. PubMed searches using MeSH terms and keywords related to CKD, uremia, and mRNA arrays were conducted. Through a computational analysis, a meta-signature that characterizes the significant intersection of differentially expressed mRNA and expected miRNAs associated with CKD-MBD was determined. Additionally, changes in gene and miRNA expressions under uremic conditions were confirmed with human Saos-2 osteoblast-like cells. A statistically significant mRNA meta-signature of upregulated and downregulated mRNA levels was identified. Furthermore, miRNA expression profiles were inferred, and computational analyses were performed with the imputed microRNA regulation based on weighted ranked expression and putative microRNA targets (IMRE) method to identify miRNAs associated with CKD occurrence. TLR4 and miR-146b levels were significantly associated with CKD-MBD. TLR4 levels were significantly downregulated, whereas primiR- 146b and miR-146b were upregulated in the presence of uremic toxins in human Saos-2 osteoblast-like cells. Differentially expressed miRNAs associated with CKD-MBD were identified through a computational analysis, and changes in gene and miRNA expressions were confirmed with an in vitro cell culture system.

Biochemical markers of mineral bone disorder in South African patients on maintenance haemodialysis

BACKGROUND AND OBJECTIVE

Despite the high mortality and morbidity associated with abnormalities in mineral and bone metabolism in haemodialysis patients, there is limited data on the pattern of mineral bone disorder in African CKD population. Therefore, the purpose of this study was to describe the pattern of mineral bone disease by evaluating biochemical parameters in patients on maintenance haemodialysis (MHD).

METHODS

We evaluated the serum/plasma intact parathyroid hormone (iPTH), corrected calcium, phosphate, total alkaline phosphatase (TALP) and 25 -OH vitamin D levels of two hundred and seven patients undergoing MHD at two dialysis centers in Johannesburg.

RESULTS

The MHD patients (133 men, 74 women) had a mean age of 54.5±15.6 years with a median dialysis vintage of 24 months (IQR, 12-48) and a mean kt/V of 1.45±0.28. The prevalence of hyperparathyroidism (iPTH >150 pg/ml), hyperphosphataemia, hypocalcaemia and 25-OH vitamin D deficiency (<30 ng/ml) was 73.4%, 57.0%, 20.3% and 80.7 % respectively. The combination of markers of bone turnover (iPTH >150pg/ml and TALP> 112 U/L) suggestive of high turnover bone disease, was present in 47.3 % of the study population. In multiple-logistic regression analysis, the odds ratio for developing hyperparathyroidism with hypocalcaemia and hyperphosphataemia were 5.32 (95% CI 1.10 - 25.9, P = 0.03) and 3.06(95 % CI 1.15 - 8.10, P=0.02) respectively. Ninety eight (47.3%) of the MHD patients had iPTH within the recommended kidney disease improving global outcome (KDIGO) guidelines.

CONCLUSION

Secondary hyperparathyroidism and 25-OH vitamin D deficiency were common in our haemodialysis patients. Hypocalcaemia and hyperphosphataemia were strong predictors for developing secondary hyperparathyroidism.

Effect of Mineral and Bone Metabolism on Restless Legs Syndrome in Hemodialysis Patients

STUDY OBJECTIVES

Restless legs syndrome (RLS) is a highly prevalent sleep disease among patients on hemodialysis. The physiopathology is still unclear, and may be multifactorial. Because of the association between iron metabolism and chronic kidney disease-mineral and bone disorders (CKD-MBD), we hypothesized that both factors would be associated with RLS.

METHODS

We have evaluated hemodialysis patients, in a face-to-face interview for the diagnosis and severity of RLS, as measured by the International Restless Legs Syndrome Study Group. Clinical, demographic, and biochemical characteristics were measured.

RESULTS

Out of 101 adult patients included, RLS was found in 29 (28.7%). Adjusted multinomial regression analysis revealed that age older than 35 years, transferrin saturation less than 47%, serum ferritin level less than 700 ng/mL, hemoglobin level less than 9.8 g/dL, serum phosphate level higher than 5.2 mg/dL, FGF-23 higher than 2,000 RU/mL, and C-reactive protein less than 1.24 mg/dL were independently associated with RLS. RLS was classified as mild, moderate, severe, and very severe in 3.4%, 41.7%, 44.8%, and 10.1% of patients, respectively. Scores of severity correlated significantly with erythropoietin dose/kg/w (p = 0.046), phosphate (p = 0.003), and inversely with serum albumin (p = 0.003) and calcium (p = 0.008). Phosphate and 25(OH)-vitamin D correlated with transferrin saturation. Patients with severe/very severe symptoms were mostly women, presented with lower serum iron, ionic calcium, and serum albumin levels and higher levels of serum phosphate, and higher percentage of 25(OH)-vitamin D deficiency and levels of FGF-23 higher than 2,000 RU/mL than did those with mild/moderate symptoms.

CONCLUSIONS

CKD-MBD factors besides iron metabolism are associated with RLS in patients on hemodialysis, providing new insights into the understanding of RLS in this population.

Phosphate binder pill burden, patient-reported non-adherence, and mineral bone disorder markers: Findings from the DOPPS

Because of multiple comorbidities, hemodialysis (HD) patients are prescribed many oral medications, including phosphate binders (PBs), often resulting in a high "pill burden." Using data from the international Dialysis Outcomes and Practice Patterns Study (DOPPS), we assessed associations between PB pill burden, patient-reported PB non-adherence, and levels of serum phosphorus (SPhos) and parathyroid hormone (PTH) using standard regression analyses. The study included data collected from 5262 HD patients from dialysis units participating in the DOPPS in 12 countries. PB prescription ranged from a mean of 7.4 pills per day in the United States to 3.9 pills per day in France. About half of the patients were prescribed at least 6 PB pills per day, and 13% were prescribed at least 12 PB pills per day. Overall, the proportion of patients who reported skipping PBs at least once in the past month was 45% overall, ranging from 33% in Belgium to 57% in the United States. There was a trend toward greater PB non-adherence and a higher number of prescribed PB pills per day. Non-adherence to PB prescription was associated with high SPhos (>5.5 mg/dL) and PTH (>600 pg/mL). Adherence to PB is a challenge for many HD patients and may be related to the number of PB pills prescribed. Prescription of a simplified PB regimen could improve patient adherence and perhaps improve SPhos and PTH levels.

The high prevalence of chronic kidney disease-mineral bone disorders: A hospital-based cross-sectional study

Mineral bone disorder (MBD) is an important complication of chronic kidney disease (CKD). However, there are limited data on the pattern of MBD in Indian CKD population. The aim of this study was to describe spectrum of MBD in patients with CKD in our center. This was a hospital-based cross-sectional observational study. Patients with stage 4 and 5 CKD were included in this study. Those receiving calcium supplement, vitamin D or its analogues, and calcimimetic were excluded. Serum/plasma levels of creatinine, albumin, calcium, phosphate, total alkaline phosphatase (TAP), intact parathormone (iPTH), and 25-OH vitaminD (25-vitD) were measured. Radiological survey of bones was carried out in all cases, and echocardiography done in selected patients. Statistical analysis was done using Sigmaplot 10.0 software. A total of 150 patients (114 males, 36 females) were included in this study. Mean age was 45.67±16.96 years. CKD stage 4 and 5D were found in 26% (n=39) and 74% (n=111) of study population, respectively. The most common underlying native kidney diseases in patients of CKD 4 and 5D were diabetic nephropathy (41.03%) and CGN (41.44%), respectively. Median (first quartile, third quartile) values for serum levels of corrected calcium (cCa), phosphate, cCaXPO4 product, TAP, plasma iPTH, and 25-vitD in stage 4 CKD were 8.36 (7.79, 8.91) mg/dL, 4.9 (3.92, 6.4) mg/dL, 41.11 (34.01, 53.81) mg(2)/dL(2), 97 (76.5, 184.25) IU/L, 231 (124.5, 430.75) pg/mL, and 12 (6.98, 23.55) ng/mL, respectively; and in stage 5D CKD were 8.36 (7.66, 8.95) mg/dL, 5.7 (4.23, 6.95) mg/dL, 46.5 (37.16, 54.47) mg(2)/dL(2), 180 (114.5, 276.25) IU/L, 288 (169.75, 625.0) pg/mL, and 18.4 (10.0, 26.4) ng/mL, respectively. Prevalence of hypocalcemia (56.41% vs. 54.95%), hyperphosphatemia (64.10% vs. 70.27%), and hyperparathyroidism (84.62% vs. 88.29%) was not different between patients with CKD 4 and 5D. However, iPTH level outside the target range and increased TAP level were significantly (P<0.001) more common in CKD stage 5D. Multiple logistic regression analysis for hyperparathyroidism revealed significant inverse correlation with cCa in CKD 5D. There were no significant differences in vitamin D status and prevalence of valvular calcification between CKD stage 4 and 5D. X-ray revealed renal osteodystrophy in 8 (5.33%) patients, while it was normal in 118 (78.67%) patients. Secondary hyperparathyroidism, hyperphosphatemia, hypocalcemia, increased TAP, and 25-OH vitamin D deficiency and insufficiency were quite common in CKD 4 and 5 patients. The commonest type of MBD in CKD 4 and 5D was secondary hyperparathyroidism.