Focus on the Possible Role of Dietary Sodium, Potassium, Phosphate, Magnesium, and Calcium on CKD Progression.

The impressive estimated number of chronic kidney disease (CKD) patients in the world justifies any possible effort at implementing preventive measures of disease progression. Renal insufficiency is associated with significant changes in the electrolyte handling and body balance of sodium, potassium, phosphate, magnesium, and calcium, all of which are biologically vital molecules. Dietary habits could contribute significantly to the optimal management of possible derangements. In this review, we examined the available evidence recommending dietary prescriptions for these five elements aiming at reducing CKD progression. Clear evidence that specific dietary prescriptions may halt or reduce CKD progression is lacking. However, some practical recommendations are possible to prescribe the best possible therapy to the individual CKD patient.

Oxygen extraction ratio to identify patients at increased risk of intradialytic hypotension.

Intradialytic hypotension (IDH) is a hemodynamic phenomenon recently associated with decreased blood oxygen saturation (SO2). The ratio between peripheral oxygen saturation (SpO2) and central venous SO2 (ScvO2) or Oxygen Extraction Ratio (OER), which represents a roughly estimate of the amount of oxygen claimed by peripheral tissues, might be used to estimate haemodialysis (HD) related hypoxic stress. Aim of this pilot study was to evaluate the relationship between OER increments during dialysis sessions (ΔOER) and episodes of IDH. We enrolled chronic HD patients with permanent central venous catheter (CVC) and no fistula, in whom ScvO2 measurement is at hand. OER ([(SpO2 - ScvO2)/SpO2] × 100) was measured in three consecutive HD sessions (HD OER sessions) before HD, after 15', 30' and 60' min and at the end of HD. Then, a one-year follow-up was planned to record the number of IDH episodes. In the 28 enrolled patients (age 74 ± 2.6 years), during 12 ± 1.2 months of follow up, incidence of IDH was 3.6%. We divided patients into two groups, above or below the median value of ΔOER at the end of HD, which was 36%. In these groups, the average incidence of IDH was 7% and 2% respectively (p < 0.01), while OER values before HD were not different. Notably, in the high ΔOER group the OER increment was evident since after 15' and was significantly higher than in the low ∆OER group (∆OER-15' = 19 ± 3.0% vs. 9.0 ± 3.0%; p < 0.05). By comparison, blood volume changes overlapped in the two groups (average change - 9 ± 0.8%). Values of ∆OER > 19% after only 15' of HD treatment or > 36% at the end of the session characterize patients with higher rates of hypotension. Intradialytic ∆OER, a parameter of tissue hypoxic stress, identifies more fragile patients at greater risk of IDH.

Inflammation, Oxidative Stress, and Bone in Chronic Kidney Disease in the Osteoimmunology Era.

Bone is not only a mineralized and apparently non-vital structure that provides support for locomotion and protection to inner organs. An increasing number of studies are unveiling new biologic functions and connections to other systems, giving the rise to new fields of research, such as osteoimmunology. The bone marrow niche, a new entity in bone physiology, seems to represent the site where a complex crosstalk between bone and immune/inflammatory responses takes place. An impressive interplay with the immune system is realized in bone marrow, with reciprocal influences between bone cells and haematopoietic cells. In this way, systemic chronic inflammatory diseases realize a crosstalk with bone, resulting in bone disease. Thus, pathogenetic links between chronic kidney disease-mineral bone disorders and osteoporosis, cardiovascular disease, and ageing are common. The aim of this narrative review is to provide a general view of the progresses in the field of bone research and their potential clinical implications, with emphasis on the links with inflammation and the connections to osteoimmunology and chemokines.

Bone, inflammation and chronic kidney disease.

Increasing knowledge on inflammatory mediators and bone metabolism highlights the relationship between inflammation and bone disease. During acute illness, inflammatory cells and cytokines modulate bone cells activity so as to mobilize calcium seemingly to supply the metabolic requirements for immune response. In case of long lasting, chronic inflammatory states a condition of maladaptive, smouldering inflammation is realized and negatively affects calcium bone balance. Aging, now nicknamed inflammaging, is regarded as a chronic inflammatory condition, characterized by increased circulating inflammatory cytokines, that contributes to the development of osteoporosis, cardiovascular diseases and chronic kidney disease. In patients with renal insufficiency, the development of bone and mineral disorders (so called CKD-MBD "syndrome") is now a recognized pathogenic factor for the seemingly accelerated process of aging and for the increased risk of cardiovascular death in these patients. The adaptive changes in mineral and bone metabolism developing in the early stages of chronic kidney disease could represent a hypothetical model of accelerated aging, osteoporosis and cardiovascular disease.

On the role of skin biopsy in the diagnosis of calcific uremic arteriolopathy: a case-based discussion.

Calciphylaxis is a rare disease characterized by ectopic calcification of skin arterioles resulting in ischemia, thrombosis and necrosis. Since end stage renal disease patients are those mainly affected, the term calcific uremic arteriolopathy (CUA) is also suggested. Early clinical manifestations are subtle, while overt necrotic ulcers may quickly spread and become infected so as to result in ominous outcome. Diagnosis might not be easy due to the number of other ischemic and non-ischemic skin lesions observed in uraemia. Skin biopsy, has been proposed as the diagnostic test and is often considered, but not systematically performed due to the hypothetical risk of further spreading of the lesions. Such ambiguity could be responsible for misdiagnosis or underdiagnosis. We review here five consecutive cases recorded in our Unit, all submitted to skin biopsy but with inconsistent results which generated some clinical frustration. Thus, we decided to carefully re-evaluate all of them together with pathologists and dermatologists. However, even after this ex-post discussion, we could not reach a complete agreement on the final diagnosis. In the meanwhile, papers were published in the literature that started to shed some light on the role of skin biopsy in the diagnosis of CUA.