losartan-potassium and Bone-Diseases--Metabolic

Topics: Acidosis; Anemia; Bone Diseases, Metabolic; Chronic Disease; Darbepoetin alfa; Diabetic Nephropathies; Diet, Protein-Restricted; Erythropoietin; Female; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hypertension; Kidney Diseases; Male; Nephrology; Renin-Angiotensin System

Although patients with either β-thalassemia or chronic kidney disease (CKD) clinically correlate with severe osteoporosis, the mechanism by which CKD exposed to high phosphate affects bone turnover has not been characterized in β-thalassemia. We aimed to determine the effects of renal insufficiency on high phosphate intake induced changes in bone metabolism after 5/6th nephrectomy in hemizygous β-globin knockout (BKO) mice. Male BKO mice manifested severe anemia and osteopenia. Nephrectomy induced renal fibrosis and reduced renal function as assessed by increased serum urea nitrogen levels. Moreover, nephrectomy increased bone turnover leading to bone loss in wild type (WT) but not BKO mice. In nephrectomized BKO, PBS in drinking water induced hyperphosphatemia, and hypercalcemia along with osteopenia in both cancellous and cortical bone. Histomorphometric analysis confirmed reduced cancellous bone volume due to decreased bone formation rate, osteoblast number and osteoclast number. The mRNA levels for Alpl, Sp7, Kl, Tnfsf11, and Tnfsf11/Tnfrsf11b were decreased in nephrectomized BKO mice drinking PBS. Interestingly, Fgf23, a bone-derived hormone produced by osteocytes and osteoblasts in response to hyperphosphatemia, were remarkably increased in nephrectomized BKO mice following PBS intake. Serum FGF23 and erythropoietin levels were markedly elevated in BKO mice. Nephrectomy decreased serum erythropoietin but not FGF23 levels. Hyperphosphatemia in BKO mice increased serum erythropoietin, FGF23, and PTH levels, nominating these factors as candidate mediators of bone loss in thalassemic mice with CKD during phosphate retention.

Topics: Animals; beta-Thalassemia; Bone Diseases, Metabolic; Erythropoietin; Fibroblast Growth Factors; Humans; Hyperphosphatemia; Male; Mice; Phosphates; Renal Insufficiency, Chronic

Increased fragility has been described in humans with polycythemia vera (PV). Herein, we describe an osteoporotic phenotype associated with decreased osteoblast activity in a mouse model of PV and another mouse of polycythemia and elevated circulating erythropoietin (EPO). Our results are important for patients with PV or those treated with recombinant EPO (rEPO).. PV and other myeloproliferative syndromes have been recently associated with an increased risk for fractures. However, the presence of osteoporosis in these patients has not been well documented. EPO, a hormone primarily known to stimulate erythropoiesis, has been shown recently to regulate bone homeostasis in mice. The aim of this study was to examine the bone phenotype of a mouse model of PV and compare it to that of animals with polycythemia caused by elevated circulating EPO.. Bone mass and remodeling were evaluated by micro-computed tomography and histomorphometry. The JAK2(V617F) knock-in mouse, a model of human PV, manifests polycythemia and low circulating EPO levels. Results from this mouse were compared to wild type (wt) controls and the tg6 transgenic mouse that shows polycythemia caused by increased constitutive expression of EPO.. Compared to wt, both JAK2(V617F) and tg6 mice had a decrease in trabecular bone mass. Tg6 mice showed an additional modest decrease in cortical thickness and cortical bone volume per tissue volume (P < 0.01) suggesting a more severe bone phenotype than JAK2(V617F). Decreased osteoblast numbers and bone formation along with normal osteoclast numbers and activity were found in both mice.. This study indicates that PV is associated with low bone mass and decreased osteoblast activity in mice. Our results support future studies of osteoporosis in affected humans. Polycythemia caused by chronically elevated circulating EPO also results in bone loss, and implications on patients treated with rEPO should be evaluated.

Topics: Animals; Bone Density; Bone Diseases, Metabolic; Bone Remodeling; Disease Models, Animal; Erythropoietin; Male; Mice, Knockout; Mice, Transgenic; Osteoblasts; Osteogenesis; Polycythemia; Polycythemia Vera; X-Ray Microtomography

Long or frequent hemodialysis schedules are reported to improve clinical outcomes. We report here our experience with an in-center, nocturnal, thrice-weekly hemodialysis program. We retrospectively analyzed the effect of switching 10 patients (8 male, age 45 ± 11 years, renal replacement therapy vintage 12 ± 8 years) from regular, 4-5 h, thrice-weekly hemodialysis to 8 h nocturnal, in-center hemodialysis as regards dialysis efficiency, chronic kidney disease-metabolic and bone disease (CKD-MBD) parameters, blood pressure, and anemia. With more intense dialysis, the mean predialysis creatinine and urea decreased significantly (1092 ± 195 vs. 961 ± 154 μmol/L, P < 0.01 and 30.8 ± 4.6 vs. 25.5 ± 2.9 mmol/L, P < 0.01), while the decrease in potassium was insignificant (5.9 ± 0.7 vs. 5.6 ± 0.5 mmol/L), but in 3/10 patients, dialysate potassium was increased. Three months after starting nocturnal hemodialysis, no significant influence on pre-dialysis blood pressure was observed (143/80 vs. 140/80 mmHg), but antihypertensive medications were reduced in two patients. The mean dry weight reduced (74 ± 12 to 72 ± 12 kg) and the mean ultrafiltration increased insignificantly (3123 ± 1174 to 3434 ± 1341 mL). Serum calcium was stable, while phosphate reduced insignificantly (1.5 ± 0.5 to 1.2 ± 0.2 mmol/L), but 6/10 patients were able to discontinue phosphate binders, the dose was reduced in one, and phosphate was added to dialysate in 3/10 patients. Intact parathyroid hormone values were within the target range, except in patients post-parathyroidectomy. There were no differences in hemoglobin (121 ± 6 vs. 122 ± 8 g/L), and the mean epoetin dose decreased insignificantly (5950 ± 3947 vs. 5250 ± 4238 IU/week). To conclude, improved phosphate and potassium control and reduction in phosphate binders were observed after switching to nocturnal hemodialysis. There was an insignificant reduction of epoetin dose and antihypertensive medications.

Topics: Adult; Antihypertensive Agents; Bone Diseases, Metabolic; Chelating Agents; Darbepoetin alfa; Dose-Response Relationship, Drug; Erythropoietin; Female; Hemoglobins; Humans; Male; Middle Aged; Phosphates; Polyethylene Glycols; Potassium; Renal Dialysis; Renal Insufficiency, Chronic; Retrospective Studies; Time Factors; Treatment Outcome

Topics: Aluminum; Anemia; Bone Diseases, Metabolic; Drug Resistance; Erythropoietin; Humans; Iron; Uremia

Topics: Aluminum; Anemia; Bone Diseases, Metabolic; Deferoxamine; Erythropoietin; Humans; Iron; Kidney Failure, Chronic; Metabolic Diseases; Recombinant Proteins; Renal Dialysis