Interplay of Vitamin D, Erythropoiesis, and the Renin-Angiotensin System

Abstract

For many years deficiency of vitamin D was merely identified and assimilated to the presence of bone rickets. It is now clear that suboptimal vitamin D status may be correlated with several disorders and that the expression of 1-α-hydroxylase in tissues other than the kidney is widespread and of clinical relevance. Recently, evidence has been collected to suggest that, beyond the traditional involvement in mineral metabolism, vitamin D may interact with other kidney hormones such as renin and erythropoietin. This interaction would be responsible for some of the systemic and renal effects evoked for the therapy with vitamin D. The administration of analogues of vitamin D has been associated with an improvement of anaemia and reduction in ESA requirements. Moreover, vitamin D deficiency could contribute to an inappropriately activated or unsuppressed RAS, as a mechanism for progression of CKD and/or cardiovascular disease. Experimental data on the anti-RAS and anti-inflammatory effects treatment with active vitamin D analogues suggest a therapeutic option particularly in proteinuric CKD patients. This option should be considered for those subjects that are intolerant to anti-RAS agents or, as add-on therapy, in those already treated with anti-RAS but not reaching the safe threshold level of proteinuria.

Vitamin D Status in Renal Transplant recipients is not Associated with Erectile Dysfunction

“…Th e fi nding of lower red blood cell and hemoglobin concentrations in VDD patients is in line with the published data on VDD association with anemia in CKD patients. Although the exact mechanism is unknown, VDD may impair erythropoiesis via immune activation within the bone marrow 23 . Out of 40 study patients, only 10 (25%) had no ED (ED 0 group), 20 patients had mild (ED 1) and seven patients mild to moderate ED (ED 2), while three patients had severe ED (ED 4 group).…”

“…A simplifi ed 5-item version of the International Index of Erectile Function (IIEF-5) was used as a diagnostic tool for ED evaluation 13 and to further divide study subjects into diff erent ED categories. According to the IIEF-5 score, the patients were categorized as no ED (ED 0; score [22][23][24][25], ED 1 (score 17-21), ED 2 (score 12-16), ED 3 (score 8-11) and ED 4 group (score ≤7). Th e groups were then compared according to serum levels of 25(OH)D, complete blood count, hemoglobin, PTH, fasting blood glucose, creatinine, high-sensitivity C-reactive protein (hs-CRP), cholesterol and triglycerides per body mass index (BMI), duration of renal replacement therapy (RRT) before TX, and kidney graft duration until analysis.…”

Iron, Hematological Parameters and Blood Plasma Lipid Profile in Vitamin D Supplemented and Non-Supplemented Young Soccer Players Subjected to High-Intensity Interval Training

“…Recently, Atkinson et al (23) reported similar relationships in healthy children and adolescents. Several possible mechanisms for the association between vitamin D and anemia have been proposed, such as a direct stimulatory proliferative effect of vitamin D on bone marrow cells via VDR (24), silencing of inflammatory reactions that lead to anemia or chronic diseases (25) or parathyroid hormone (PTH)-dependent alteration in erythrocyte osmotic resistance (26). However, so far, the results of observational studies have not been confirmed by RCT (27)(28)(29).…”

Decreased Serum 25-hydroxyvitamin D Level Causes Interventricular Septal Hypertrophy in Patients on Peritoneal Dialysis: Cardiovascular Aspects of Endogenous Vitamin D Deficiency

“…Vitamin D metabolites have renoprotective effect by antiproteinuric, anti-inflammatory, and immunomodulatory properties and by suppression of renin-angiotensin-aldosterone system (RAAS) [22]. Low serum 25-OH-D level activates (RAAS) and increases fibroblast growth factor which are associated with progression of renal injury [23, 24].…”