Hyperphosphatemia In Dialysis Patients Research Articles

Management of hyperphosphataemia in dialysis patients: role of phosphate binders in the elderly.

Phosphorus control remains a relevant clinical problem in dialysis patients. With age, however, serum phosphorus level decreases significantly because of a spontaneous decrease in protein intake. Older patients usually need lower doses of phosphorus binders. Nevertheless, hyperphosphataemia is observed in a quarter of patients aged >65 years. Phosphorus retention is related to an imbalance between phosphorus intake and removal by dialysis, and is usually aggravated when vitamin D analogues are employed. Hyperphosphataemia induces secondary hyperparathyroidism and the development of osteitis fibrosa. Recent publications describe an association between phosphorus retention and increased calcium and phosphorus product (Ca2+ x P), with significant progression of tissue calcification and higher mortality risk. Dietary intervention, phosphorus removal during dialysis and phosphorus binders are current methods for the management of hyperphosphataemia. However, the phosphorus removed by standard haemodialysis is insufficient to achieve a neutral phosphorus balance when protein intake is >50 g/day. Additional protein restriction may impose the risk of a negative protein balance. More frequent dialysis may help to control resistant hyperphosphataemia. Phosphorus binders constitute the mainstay of serum phosphorus level control in end-stage renal disease patients. Aluminium-based phosphorus binders, associated with toxic effects, have largely been substituted by calcium-based phosphorus binders. However, widespread use of calcium-based phosphorus binders has evidenced the frequent appearance of hypercalcaemia and long-term progressive cardiovascular calcification. Sevelamer, a relatively new phosphorus binder, has proved efficacious in lowering serum phosphorus and parathyroid hormone (PTH) levels without inducing hypercalcaemia. Furthermore, several investigators have reported that sevelamer may prevent progression of coronary calcification. However, its efficacy in severe cases of hyperphosphataemia remains to be confirmed in large series. There are no specific guidelines for phosphorus control in the elderly. Until more information is available, levels of mineral metabolites should be targeted in the same range as those recommended for the general population on dialysis (calcium 8.7-10.2 mg/dL, phosphorus 3.5-5.5 mg/dL and Ca2+ x P 50-55 mg2/dL2). PTH values over 120 ng/L help to avoid adynamic bone disease. Since elderly patients have a higher incidence of adynamic bone (which buffers less calcium) and vascular calcification, sevelamer should be the phosphorus binder of choice in this population; but sevelamer is costly and its long-term efficacy has not been definitively validated. Patients with low normal levels of calcium may receive calcium-based phosphorus binders with little risk. Patients with low values of PTH and high normal calcium should receive sevelamer. Tailored combinations of calcium-based phosphorus binders and sevelamer should be considered, and calcium dialysate concentration adjusted accordingly.

Hyperphosphatemia in dialysis patients: is there a role for focused counseling?

Background: Elevated serum phosphorus (P) and calcium-P product (CaXP) are associated with cardiac mortality in dialysis patients. A CaXP <55 is considered acceptable by most authorities. Because nutrition practices can modulate CaXP, we designed a survey to study the impact of the patients’ levels of education and disease awareness on their CaXP. Methods: A survey questionnaire with 5 didactic questions pertaining to hyperphosphatemia and P-binders and 5 questions related to patient attitudes and beliefs was administered to all patients in a hemodialysis unit. The association of CaXP >55 with the patients’ level of education, their score on the survey (didactic part, score 0 to 5), parathyroid hormone (PTH) levels, hyperkalemia, hypertension, and vascular disease were studied. Results: Of the 117 patients (61 men, age 56.5 ± 18 years) who participated in the survey, 49 (42%) had CaXP >55 and 100 (85%) were on P binders. Thirty-seven (31.6%) had at least some college education. Eighty-seven patients (74%) failed to identify foods rich in P; 61% were unaware of complications related to high CaXP. Patients with CaXP >55 were less likely to have college education (20% versus 39%, P = .04), and had lower survey scores (2.4 ± 1.3 versus 2.6 ± 1.4, P = NS). Patients with college education scored higher (2.9 ± 1.1 versus 2.3 ± 1.4, P = .014). Furthermore, CaXP >55 was significantly associated with hyperkalemia ( P = .02), high PTH levels ( P < .001), and hypertension ( P = .02), but not with >Kt/V, URR, type of hemodialysis access, or vascular diseases. Conclusion: The majority of patients in the survey were ignorant of basic facts pertaining to high P and CaXP. The association of CaXP >55 with hyperkalemia, and not with Kt/V, suggests dietary noncompliance rather than inadequate dialysis. Patients with less education were more likely to have CaXP >55. Because this related mostly to misperception of simple facts that affect dietary habits, there is need for focused counseling of these patients at a level appropriate for their literacy skills.

Responses to a phosphate binder given with meals or between meals

• ■ Objective: To determine whether the phosphate binder calcium carbonate is effective in preventing hyperphosphatemia in dialysis patients when administered between meals as well as with meals. • ■ Design: An open-label, nonrandomized, cross-over study. • ■ Setting: Three hemodialysis centers where staff is experienced in the conduct of clinical trials. • ■ Patients: Clinically stable adult patients on hemodialysis for end-stage renal disease who were successfully undergoing treated for hyperphosphatemia with calcium carbonate. • ■ Interventions: After a 1 to 7 day washout period from prior calcium carbonate treatment and documentation of baseline hyperphosphatemia, patients underwent a 2-week period in which calcium therapy was reinstituted and titrated to the dose that achieved optimal serum calcium and phosphorus levels. The patients then received their optimized dose of calcium carbonate administered first in divided doses with meals for 2 weeks and then between meals for 2 weeks. • ■ Main outcome measures: Comparison of serum calcium and phosphorus concentrations after 2 weeks of calcium carbonate therapy administered with meals or between meals. • ■ Results: Hyperphosphatemia was prevented by both regimens of calcium carbonate, and there were no significant differences in calcium or phosphorus blood levels when calcium carbonate was administered orally with meals or between meals. No difference in the incidence of adverse effects was noted between the two dosage regimens. • ■ Conclusion: The data suggest that the dosing of phosphate binders such as calcium carbonate to prevent hyperphosphatemia can be more flexible than previously perceived.

Calcium carbonate as a phosphate binder in dialysis patients: Evaluation of an enteric-coated preparation and effect of additional aluminium hydroxide on hyperaluminaemia

Calcium carbonate has been successfully used as a phosphate binder in patients with chronic renal failure; however, a high frequency of hypercalcaemia has been reported. To study the effects of calcium carbonate preparations with different dissolution characteristics on the incidence of this side effect, we conducted a double-blind, crossover trial in 21 patients undergoing chronic haemodialysis. Aluminum hydroxide therapy was replaced with calcium carbonate. The subjects then randomly received either an enteric-coated or a gastric-coated preparation. Calcium carbonate (3.1-3.6 g/d) controlled serum phosphate concentrations as effectively as aluminium hydroxide (2.9 g/d). Concurrently, there was a significant rise in mean serum calcium and a fall in serum concentrations of both parathyroid hormone and osteocalcin, the latter suggesting a decrease in bone turnover. Overall, hypercalcaemic episodes developed in 9 patients (43%) and occurred at a considerable frequency (33 episodes per 100 patient-months) during treatment with the gastric-coated formulation. Following conversion to enteric-coated calcium carbonate (3.6 g/d) patients had fewer occurrences of hypercalcaemia (12 episodes per 100 patient-months, P less than 0.05) and, as compared to the gastric-coated preparation, increases in serum calcium greater than 3.00 mmol/l were not observed at all. Hyperaluminaemia was regressive during therapy with calcium carbonate, but addition of small doses of aluminium hydroxide caused a large rise in serum aluminium concentrations after infusion of desferrioxamine, indicating an enhanced rate of absorption or aberrant compartmentalization of aluminium. We conclude that calcium carbonate can control hyperphosphataemia in dialysis patients.(ABSTRACT TRUNCATED AT 250 WORDS)

透析患者におけるリン摂取量と高リン血症に対する低リンミルクの効果について

維持血液透析患者6名に牛乳の代用として低リンミルク (LPK®) を飲用するよう食事指導を行い, その前後で食事調査を行いリン摂取量および高リン血症に対する効果について検討を行った.栄養摂取量においてLPK飲用後, 飲用前と比較し熱量, 蛋白質, 脂質, 糖質の変化はなく, リン摂取量は801.0±254.2mg (mean±SD) より679.2±166.2mgと低下したのに対し, カルシウム摂取量は424.1±174.9mgより526.6±156.3mgと増加した. このため一日摂取カルシウム/リン比は有意に増加した (p<0.01).血清リン濃度はLPK飲用2週間後に有意な低下 (p<0.05) を認め, その効果は飲用前の血清リン濃度が高値の患者に著明であった.さらに, 血中副甲状腺ホルモン (PTH) 濃度の高値の一例において血清リン濃度の低下に伴い血清intact-PTHは抑制を受けたが, この間血清カルシウム濃度には変化を認めなかった.以上の結果より牛乳の代用としてLPKを飲用することにより慢性腎不全透析患者のカルシウム, リン管理は容易になることが示され, 高リン血症の是正により短期的にはPTH分泌が抑制される可能性が示唆された.

Control of Hyperphosphatemia in Dialysis Patients

Control of Hyperphosphatemia in Dialysis Patients

Hemodialysis / hemofiltration: A report of a controlled cross-over study

In 14 stable ESRD patients an ABA cross-over study comparing conventional hemodialysis with post-dilution hemofiltration was performed in order to test the validity of clinical benefits reported for hemofiltration. No effect on blood-pressure could be observed in hypertensive hemofiltration patients when body weight was kept constant. The claimed positive effect of hemofiltration on hyperphosphatemia in dialysis patients could not be confirmed. A treatment with 3x81 I infusate per week seems to be insufficient treatment in regard to small molecule removal especially in heavy patients without any residual renal function. The decrease in urea nitrogen generation rate during the hemofiltration period might be the result of the lower small molecule removal in hemofiltration when compared to hemodialysis. The main clinical benefit of hemofiltration results from improved tolerance to volume removal due to improved hemodynamic stability during treatment.