Vitamin D insufficiency and bone fractures in patients on maintenance hemodialysis.

BACKGROUND: The incidence of fractures is substantially increased in patients with chronic kidney disease (CKD) compared to the general population. The factors associated with increased bone fracture in this population are not well understood. Vitamin D deficiency has been associated with decreased bone mass and higher incidence of fractures in the general population. In this study, we aimed to assess the association between fracture and vitamin D status and other factors potentially associated with fracture in patients on maintenance hemodialysis. METHODS: One hundred and forty-four patients were assessed and interviewed about previous low-trauma fractures. Evidence of fracture was obtained from medical records and also through patient interviews. Routine laboratory results were collected from medical records. Serum intact PTH (iPTH) and 25(OH) vitamin D(3) were measured. All patients underwent bone densitometry of the lumbar spine, femoral neck and distal radius. Bone quality was also assessed with quantitative bone ultrasound (QUS). Descriptive statistics, logistic regression models were used to analyze factors associated with fractures. RESULTS: One hundred and thirty patients were included in the final analysis. Patients with fractures (n = 21) had lower 25(OH) vitamin D(3) levels (15.8 nmol/l (interquartile range, IQR: 27) vs. 30.0 nmol/l (IQR: 28.5), P = 0.029), were more likely females, had longer duration of end-stage kidney disease, and lower bone mineral density (BMD) at the distal radius. QUS parameters were not associated with fractures. Multivariate analyses revealed that serum 25(OH) vitamin D(3) concentration, BMD at the radius, iPTH less than 100 pg/ml and history of fractures were independent predictors of new bone fracture after the initiation of dialysis therapy. CONCLUSION: Increased bone fragility in dialysis patients is associated with vitamin D deficiency and relative hypoparathyroidism in addition to reduced BMD at the radius. Further studies are needed to determine whether patients with vitamin D deficiency benefit from vitamin D supplementation to reduce fracture risk.

Bone mineral density and parathyroid function in patients on maintenance hemodialysis.

BACKGROUND: The relationship between parathyroid function, an important determinant of bone turnover, and bone mineral density (BMD) in patients with chronic kidney disease is not fully understood. We wanted to analyze the association between BMD and parathyroid function in hemodialysis patients in details. METHODS: In a cross-sectional design, data from 270 patients (age 55 ± 15 years, 60% men, all Caucasian) on maintenance hemodialysis were analyzed. All patients underwent dual energy X-ray absorptiometry of the lumbar spine (LS), femoral neck (FN) and distal radius (DR). In addition to routine laboratory tests, blood samples were collected for iPTH, serum markers of bone metabolism (alkaline phosphatase, type I collagen crosslinked-C-telopeptide) and 25OH vitamin D. RESULTS: Based on Z-scores, bone mineral density was moderately reduced only at the femoral neck in the total cohort. The average Z-score of the "low PTH" group (iPTH < 100 pg/ml) was not different from the Z-score of patients with iPTH in the "target range" (100-300 pg/ml) at any measurement site. While iPTH was negatively correlated with BMD at all measurement sites in patients with iPTH > 100 pg/ml (rho = -0.255, -0.278 and -0.251 for LS, FN and DR, respectively, P < 0.001 for all), BMD was independent of iPTH in patients with iPTH < 100 pg/ml. Furthermore, iPTH was not associated with serum markers of bone metabolism, but these markers were negatively correlated with BMD in the "low PTH" group. CONCLUSIONS: Low PTH levels are not associated with low BMD in patients with end-stage kidney disease. Furthermore, bone metabolism seems to be independent of iPTH in patients with relative hypoparathyroidism likely reflecting skeletal resistance to PTH.

Serum 25(OH)-cholecalciferol concentration is associated with hemoglobin level and erythropoietin resistance in patients on maintenance hemodialysis.

BACKGROUND: Resistance to erythropoiesis-stimulating agents (ESAs) has been observed in patients with chronic kidney disease (CKD) and it is associated with clinical outcomes. The presence of ESA resistance cannot always be explained by the known risk factors of the condition, suggesting that additional factors may be involved. We wanted to test the hypothesis that vitamin D insufficiency is associated with lower hemoglobin (Hb) and ESA resistance in patients on maintenance hemodialysis (HD). METHODS: Data from patients receiving maintenance HD in a single dialysis center were extracted from the medical records in a retrospective chart review. Basic patient characteristics and laboratory data including Hb, serum albumin, intact parathyroid hormone and serum 25(OH)-cholecalciferol (25(OH)D(3)) levels were collected. ESA dose and Kt/V were extracted from the dialysis charts. Correlation analysis and multivariate linear regression analysis were used to reveal potential independent associations between clinical and laboratory parameters and ESA resistance. RESULTS: Data from 142 patients were analyzed. Serum 25(OH)D(3) concentration was significantly correlated with Hb (ρ = 0.186, p < 0.05) and also with ESA dose/Hb index (ρ = 0.230, p < 0.01). In multivariable regression analyses, serum 25(OH)D(3) concentration remained significantly associated with both Hb and ESA dose/Hb index after controlling for potentially important confounders. CONCLUSION: Serum 25(OH)D(3) concentration is independently associated with erythropoietin responsiveness in CKD patients on maintenance HD. If this association will be confirmed, treatment trials looking at the effect of vitamin D supplementation on anemia treatment in CKD patients may be warranted.

The role of autologous antebrachial arteriovenous fistula in the strategy of access planning for chronic uremic patients on hemodialysis.

AIM: The number of arteriovenous (AV) fistula creation increases worldwide. Haemodialysis is more effective, patients live longer, and they need more access operations. The optimal strategy for the order and sequence of the different type and localization of AV fistulas remains obscure. Based on internationally acclaimed guidelines, autogenous access should be performed whenever possible and the first operation of choice is the radiocephalic fistula at the wrist, the second type is the elbow fistula. The area between the standard exposures means also good access area and its usage is not emphasized properly. Our aim was to study the short and long-term the results of autologous forearm fistulas. METHODS: Between 1997 and 2005 we performed 1018 AV shunts in an academic tertiary care centre. Ninety-seven autologous antebrachial AV shunts were performed. The average follow-up time was 31.3 months. We examined the patency rate and its connection with different variables such as diabetes mellitus, acute or chronic operative situations, indications for surgery, diameter and quality of the vein. RESULTS: The primary patency rates were 93%, 79.5% and 61.2% at the end of years 1, 2 and 6, respectively. The patency rate was not significantly affected by any of the examined variables mentioned above. CONCLUSION: The patency rate of the autologous antebrachial AV shunt is comparable to the wrist and elbow fistulas, so our results support the practice of performing fistula at this atypical localization. Proximal autologous fistulas and prosthetic graft implantation could be postponed, this way valuable time could be saved for the uremic patients.

Canine neosporosis in Hungary: screening for seroconversion of household, herding and stray dogs.

In order to assess the seroprevalence of canine neosporosis 651 blood samples were collected from 586 household, 41 herding and 24 stray dogs, at small animal clinics in four large cities and other places of Hungary. Nineteen (2.9%) showed positivity in the IFAT with titres between 1:80 and 1:10240. Two dogs with high titres of antibodies to Neospora caninum had neuromuscular signs (imbalance, tremor) and a further one developed papulomatous, ulcerative and necrotizing dermatitis. There was no correlation between titers and age, sex, breed or keeping place. Although more male dogs had antibodies to N. caninum than females in case of both household and herding dogs, this association was not significant. No breed predisposition was observed. However, dogs with seroconversion were significantly more prevalent among rural (6%) than among urban dogs (1%), indicating that dogs in the countryside may have contact with or access to potentially infected offal from cattle and other intermediate hosts more frequently than those in large cities. Furthermore, significantly more herding dogs (29.3%) had antibodies to N. caninum than household dogs (1.2%), confirming the association between the occurrence of neosporosis and dog keeping on farms. The 12 dogs found seropositive among herding ones lived on 6 farms, on 5 of which seropositive cattle were also identified. This is the first report on the prevalence of N. caninum infection in dogs in Hungary.

Serum 25(OH)-vitamin D levels and bone metabolism in patients on maintenance hemodialysis.

AIMS: An increasing amount of evidence suggests that 25-hydroxy vitamin D3 (25(OH)D3) may contribute to the bone health of patients with chronic kidney disease (CKD). The underlying vitamin D status of these patients, however, has often been neglected. In a cross-sectional study we assessed the association between vitamin D status and parathyroid function, bone turnover, bone mass and structure in patients on maintenance hemodialysis. METHODS: 69 patients on maintenance hemodialysis were assessed by bone densitometry (DEXA) and quantitative bone ultrasound (QUS). Serum 25-hydroxy vitamin D3 levels, serum markers of bone turnover and clinical data were tabulated. RESULTS: A high prevalence of potentially significant vitamin D3 deficiency was found in this patient group: 59% of the patients had a 25(OH)D3 level below 20 nmol/l. There was a significant negative correlation between serum 25(OH)D3 levels and serum intact parathyroid hormone (iPTH) (r = -0.231, p < 0.05), and this association remained significant after controlling for potential covariables. Furthermore, we show here that serum 25(OH)D3 concentration is positively correlated with bone mineral density (BMD) measured at the radius (r = 0.424, p < 0.01). Finally, we show for the first time that 25(OH)D3 levels are significantly and independently correlated with broadband ultrasound attenuation (beta = 0.262, p < 0.05) measured with calcaneal quantitative bone ultrasound (QUS) in patients with chronic renal failure. CONCLUSION: Vitamin D3 deficiency may contribute to the impaired bone health of patients on maintenance dialysis.

Effect of propranolol on heart rate variability in patients with end-stage renal disease: a double-blind, placebo-controlled, randomized crossover pilot trial.

BACKGROUND: Low heart rate variability (HRV) is an independent risk factor of cardiac mortality in patients with end-stage renal disease (ESRD). It has been explained by uremic parasympathetic neuropathy. Sympathetic overactivity can also reduce HRV. Our aim was to determine whether there is vagal activity in ESRD patients that is masked by sympathetic activity. METHODS: The effect of propranolol on HRV was examined in 13 patients with ESRD, aged 20.1 +/- 7.6 years without diabetes. All patients were given intravenous propranolol (0.05 mg/kg) once and placebo once in a randomized, double-blind way, with an interval of 6.6 days (mean, range: 2-9). Propranolol was administered before hemodialysis treatment, after 40 minutes supine resting period. HRV was registered for 10 minutes, during supine, before and after the injection. Patients' HRV data were compared to that of 29 age-matched healthy controls. RESULTS: Initially, both high-(HFV) and low-frequency (LFV) bands of heart rate variability were lower in ESRD patients compared to controls (p < 0.001 for both). Propranolol resulted in a significant increase of HFV (propranolol: AlgHFV = 0.182 (0.027 - 0.337), placebo: deltalgHFV = -0.029 (-0.128 - +0.070); p = 0.032). Elevation of LFV was not significant. Six patients had an elevated plasma norepinephrine and/or epinephrine level. Plasma dopamine level was elevated in all but 1 patient (mean: 432 pmol/l, 95% CI: 320-543) and showed an inverse relationship with the increase of IgHFV secondary to propranolol (r = -0.66, p = 0.014). CONCLUSIONS: Low HFV of ESRD patients can be improved by beta-adrenergic blockade. It demonstrates that there is some vagal activity in ESRD that is masked by sympathetic activity. Therefore, altered sympathovagal balance of ESRD patients should be taken into consideration in the assessment of vagal uremic neuropathy.