The Impact of Cholecaciferol Supplementation on Bone Mineral Density in Long-Term Kidney Transplant Recipients.

Although reduced bone mineral density (BMD) is associated with a higher risk of fractures, morbidity, and mortality in kidney transplant patients (KTRs), there is no consensus on optimal treatment for the alterations of BMD in this population. This study aims at assessing the effect of cholecalciferol supplementation on BMD over a follow-up period of 2 years in a cohort of long-term KTRs. Patients with age ≥ 18 years were included and divided into two subgroups based on treatment with bisphosphonate and/or calcimimetics and/or active vitamin D sterols (KTRs-treated) or never treated with the above medications (KTRs-free). BMD was evaluated at lumbar vertebral bodies (LV) and right femoral neck (FN) with standard DEXA at the beginning and end of the study. According to World Health Organization (WHO) criteria, results were expressed as T-score and Z-score. Osteoporosis and osteopenia were defined as T score ≤ -2.5 SD and T score < -1 and >-2.5 SD, respectively. Cholecalciferol was supplemented at a dose of 25,000 IU/week over 12 weeks followed by 1500 IU/day. KTRs-free (n. 69) and KTRs-treated (n. 49) consecutive outpatients entered the study. KTRs-free were younger (p < 0.05), with a lower prevalence of diabetes (p < 0.05) and of osteopenia at FN (46.3 % vs. 61.2 %) compared to KTRs-treated. At the entry none of the study subjects had a sufficient level of cholecalciferol; Z-score and T-score at LV and FN were not different between groups. At the end of the study period, serum cholecalciferol concentration was significantly increased in both groups (p < 0.001); the KTRs-free group presented an improvement in both T-score and Z-score at LV (p < 0.05) as well as a lower prevalence of osteoporotic cases (21.7% vs. 15.9%); in contrast, no changes were recorded in KTR-treated individuals. In conclusion, supplementation with cholecalciferol ameliorated Z-score and T-score at LV in long-term KTRs who had been never treated with active or inactive vitamin D sterols, bisphosphonates, and calcimimetics. Future endeavours are needed to confirm these preliminary findings.

Bone Mineral Density Changes in Long-Term Kidney Transplant Recipients: A Real-Life Cohort Study of Native Vitamin D Supplementation.

Vitamin D insufficiency has been associated with reduced bone mineral density (BMD) in kidney transplant patients (KTRs). However, the efficacy of vitamin D supplementation on BMD remains poorly defined, especially for long-term KTRs. We aimed to investigate the effect of native vitamin D supplementation on the BMD of KTRs during a 2-year follow-up. Demographic, clinical, and laboratory data were collected. BMD was evaluated with standard DEXA that was performed at baseline (before vitamin D supplementation) and at the end of study period. BMD was assessed at lumbar vertebral bodies (LV) and right femoral neck (FN) by a single operator. According to WHO criteria, results were expressed as the T-score (standard deviation (SD) relative to young healthy adults) and Z-score (SD relative to age-matched controls). Osteoporosis and osteopenia were defined as a T-score ≤ -2.5 SD and a T-score < -1 and a > -2.5 SD, respectively. Based on plasma levels, 25-OH-vitamin D (25-OH-D) was supplemented as recommended for the general population. Data from 100 KTRs were analyzed. The mean study period was 27.7 ± 3.4 months. At study inception, 25-OH-D insufficiency and deficiency were recorded in 65 and 35 patients. At the basal DEXA, the percentage of osteopenia and osteoporosis was 43.3% and 18.6% at LV and 54.1% and 12.2% at FN, respectively. At the end of the study, no differences in the Z-score and T-score gains were observed. During linear mixed model analysis, native vitamin D supplementation was found to have a negative nitration with Z-score changes at the right femoral neck in KTRs (p < 0.05). The mean dose of administered cholecalciferol was 13.396 ± 7.537 UI per week; increased 25-OH-D levels were found (p < 0.0001). Either low BMD or 25-OH-vitamin D concentration was observed in long-term KTRs. Prolonged supplementation with 25-OH-D did not modify BMD, Z-score, or T-score.

Muscle protein turnover and low-protein diets in patients with chronic kidney disease.

Adaptation to a low-protein diet (LPD) involves a reduction in the rate of amino acid (AA) flux and oxidation, leading to more efficient use of dietary AA and reduced ureagenesis. Of note, the concept of 'adaptation' to low-protein intakes has been separated from the concept of 'accommodation', the latter term implying a decrease in protein synthesis, with development of wasting, when dietary protein intake becomes inadequate, i.e. beyond the limits of the adaptive mechanisms. Acidosis, insulin resistance and inflammation are recognized mechanisms that can increase protein degradation and can impair the ability to activate an adaptive response when an LPD is prescribed in a chronic kidney disease (CKD) patient. Current evidence shows that, in the short term, clinically stable patients with CKD Stages 3-5 can efficiently adapt their muscle protein turnover to an LPD containing 0.55-0.6 g protein/kg or a supplemented very-low-protein diet (VLPD) by decreasing muscle protein degradation and increasing the efficiency of muscle protein turnover. Recent long-term randomized clinical trials on supplemented VLPDs in patients with CKD have shown a very good safety profile, suggesting that observations shown by short-term studies on muscle protein turnover can be extrapolated to the long-term period.

Vitamin D in kidney transplant recipients
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Kidney transplant recipients (KTRs) are susceptible to low levels of vitamin D, which may be responsible for mineral and bone metabolism disorders and play some role in the occurrence of cardiovascular, metabolic, immunologic, neoplastic, and infectious complications after kidney transplant. Kidney Disease Improving Global Outcomes (KDIGO) guidelines of the year 2017 recommended vitamin D supplementation in the first 12 months after transplant using the same treatment strategies for the general population. However, no recommendations are provided after the first 12 months due to a lack of sufficient data. This review analyses some studies that assessed the vitamin D status of KTRs and the effects of nutritional and active vitamin D supplementation on bone mineral density, cardiovascular disease, proteinuria, and graft function in KTRs.

Trained breathing-induced oxygenation acutely reverses cardiovascular autonomic dysfunction in patients with type 2 diabetes and renal disease.

AIMS: Cardiovascular autonomic dysfunction, evaluated as baroreflex sensitivity (BRS), could be acutely corrected by slow breathing or oxygen administration in patients with type 1 diabetes, thus suggesting a functional component of the disorder. We tested this hypothesis in patients with the type 2 diabetes with or without renal impairment. METHODS: Twenty-six patients with type 2 diabetes (aged 61.0 ± 0.8 years, mean ± SEM; duration of diabetes 10.5 ± 2 years, BMI 29.9 ± 0.7 kg/m(2), GFR 68.1 ± 5.6 ml/min) and 24 healthy controls (aged 58.5 ± 1.0 years) were studied. BRS was obtained from recordings of RR interval and systolic blood pressure fluctuations during spontaneous and during slow, deep (6 breaths/min) controlled breathing in conditions of normoxia or hyperoxia (5 l/min oxygen). RESULTS: During spontaneous breathing, diabetic patients had lower RR interval and lower BRS compared with the control subjects (7.1 ± 1.2 vs. 12.6 ± 2.0 ms/mmHg, p < 0.025). Deep breathing and oxygen administration significantly increased arterial saturation, reduced RR interval and increased BRS in both groups (to 9.6 ± 1.8 and 15.4 ± 2.4 ms/mmHg, respectively, p < 0.05, hyperoxia vs. normoxia). Twelve diabetic patients affected by chronic diabetic kidney disease (DKD) presented a significant improvement in the BRS during slow breathing and hyperoxia (p < 0.025 vs. spontaneous breathing during normoxia). CONCLUSIONS: Autonomic dysfunction present in patients with type 2 diabetes can be partially reversed by slow breathing, suggesting a functional role of hypoxia, also in patients with DKD. Interventions known to relieve tissue hypoxia and improve autonomic function, like physical activity, may be useful in the prevention and management of complications in patients with diabetes.

Anaemia management in non-dialysis chronic kidney disease (CKD) patients: a multicentre prospective study in renal clinics.

BACKGROUND: Knowledge on anaemia management in non-dialysis chronic kidney disease (ND-CKD) patients regularly followed in renal clinics is scarce although being essential to identifying areas of therapeutic improvement. METHODS: We prospectively evaluated anaemia management in two visits, performed 6 months apart, in 755 prevalent ND-CKD stage 3b-5 patients followed in 19 nephrology clinics from ≥6 months. Anaemia was defined as severe (Hb <11 g/dL) or mild (Hb: 11-13.5 in males and 11-12 g/dL in females); iron deficiency (ID) was defined as transferrin saturation (TSAT) <20% and/or ferritin <100 ng/mL. Primary endpoint was the change of anaemia and ID prevalence between baseline and 6-month visit. Secondary endpoint was the prevalence of clinical inertia to either ESA or iron supplementation, that is, the lack of ESA or iron prescription despite Hb <11 g/dL or ID. RESULTS: Age was 69 ± 13 years and GFR 27.5 ± 10.0 mL/min/1.73 m(2); male gender, diabetes and prior cardiovascular disease were 57.2, 30.1 and 30.1%, respectively. Prevalence of severe and mild anaemia was 18.0 and 44.0% at baseline and remained unchanged at Month 6 (19.3 and 43.2%). ID was prevalent at both visits (60.1 and 60.9%). Clinical inertia to ESA was similar at baseline and at Month 6 (39.6 and 34.2%, respectively, P = 0.487) and it was less frequent than clinical inertia to iron therapy (75.7 and 72.0%, respectively). CONCLUSIONS: This study shows that anaemia prevalence is unexpectedly high in the setting of tertiary nephrology care. This was due to a persistent clinical inertia in the anaemia management, remarkable for iron supplementation and less critical, but still significant, for ESA treatment.