Modalidade de diálise e o controle do hiperparatireoidismo secundário / Modality of dialysis and the management of secondary hyperparathyroidism

A redução dos níveis de vitamina D e a retenção de fósforo na doença renal crônica estimulam a proliferação celular da paratireóide, enquanto a liberaçãoaguda de PTH pela glândula é mais dependente do nível de cálcio ionizado no líquido extracelular. Os balanços de fósforo e de cálcio nos pacientes emdiálise assim como a influência que exercem sobre a função da paratireóide e a remodelação óssea são modificáveis por alguns medicamentos como osquelantes de fósforo e a vitamina D e, também, pela prescrição da diálise. Em especial, a concentração de cálcio no dialisato, tanto na hemodiálise quantona diálise peritoneal, pode ter um papel importante no manuseio do hiperparatireoidismo secundário.

Low vitamin D levels and phosphorus retention stimulate parathyroid cell proliferation in chronic kidney disease, whereas acute glandular PTH release is mainly dependent on ionized calcium concentration in the extracellular fluid. Phosphorus and calcium balance in patients on dialysis and their effects on parathyroid function and bone turnover can be influenced by medications such as phosphate binders and vitamin D as well as by dialysis prescription. Of note, the calcium concentration in dialysis solution, on either hemodialysis or peritoneal dialysis can have a special role in the management of renal osteodystrophy.

Clinical Usefulness of Low Calcium Dialysate in CAPD Patients with High Risk of Low-turnover Bone Disease / 대한신장학회잡지

Hypercalcemia is a common complication in CAPD patients treated with calcium-containing phosphate binders and using the standard dialysate(Ca++ : 3.5 mEq/L). Furthermore, the high calcium concentration in standard dialysate may have a suppressive effect on parathyroid hormone(iPTH) level, contributing to the high prevalence of low-urnover bone disease. We studied the effect of low calcium dialysate(Ca++ : 2.5 mEq/L) for those patients with high risk of low- turnover bone disease. Among 386 patients(1996. 1.- 1999. 12.) who had been stable on CAPD for at least 3 months, 46 patients were included in this study. The patients were divided into 3 groups on the basis of the iPTH levels(10 mg/dL) before the conversion to low calcium dialysate. Group 1(n=29), iPTH 10 mg/dL; Group 2 (n=14), iPTH 150 pg/mL and Ca++ >10 mg/ dL. During a 2-month run-in period, those patients were treated with standard dialysate. After that, a 12-month therapy with low calcium dialysate was followed. Biochemical data including calcium, phosphorus, iPTH and alkaline phosphatase were measured regularly and daily phosphate binder and calcitriol intake(pill counting) were assessed during the run-in and therapy period. We obtained the following result: the prevalence of hypercalcemia(Ca++>10.5 mg/dL) was 5.7%(22/ 386 patients). Serum calcium levels decreased during the therapy period(12 months)(10.5+/-1.4 vs 9.4+/-1.3 mg/dL, p<0.05). Serum phosphorus levels remained unchanged. Mean serum alkaline phosphatase level increased(203.0+/-92.9 vs 257.2+/-103.4 U/L, p<0.05). Serum iPTH levels increased (92.7+/-128.8 vs 225.3+/-237.3 pg/mL,p<0.05). The mean intake of oral phosphate binders was not significantly different between run-in period and therapy period. But calcitriol doses increased 0.038+/-0.087 at run-in period to 0.158+/-0.288 tablets/person/day at therapy period(p<0.05). In the six patients, low calcium dialysate was converted to standard dialysate due to high iPTH level (n=3), symptomatic hypo calcemia(n=2), and uncontrolled edema(n=1). In conclusion, in the study of 46 patients over 12 month period, the usage of 2.5 mEq/L calcium dialysate resulted in a significant decrement in calcium levels and increased iPTH levels. Therefore, we propose that dialysis with a low calcium dialysate is an acceptable form of therapy for the patients with high risk of low-turnover bone disease showing hypercalcemia and low iPTH level. However, further study will be needed for evaluating the effect of low calcium dialysate in low-turnover bone disease.

Clinical Usefulness of Low Calcium Dialysate in Continuous Ambulatory Peritoneal Dialysis (CAPD) Patients / 대한신장학회잡지

Hypercalcemia is a common complication in CAPD patients treated with calcium-containing phosphate binders and using the standard dialysate (SCD) calcium concentration of 3.5mEq/L. We performed a retrospective study in 25 CAPD patients to determine whether a low calcium dialysate (LCD) containing 2.5mEq/L calcium would reduce the incidence of hypercalemia with adequate control of serum inorganic phosphate levels and diminish the need to use aluminum-containing phosphate binders. All patients had previously used SCD before converting to LCD. The incidence of hypercalcemia (more than 2 episodes of corrected serum calcium > or = 10.5mg/dL) tended to be lower after converting to LCDl 0.27 (0-2.76) vs. 0 (0-1.97) episodes/patient-yearl. Intact PTH level increased from 38.8 (0.1-1599.3)pg/mL to 70.6 (9.5-1540.0)pg/mL after conversion, but there was no statistical sifnificance. Serum calcium, inorganic phosphate, alkaline phosphatase and bicarbonate levels did not change after converting to LCD. We were able to reduce aluminum hydroxide dosagel 1.09 (0-10.88) vs. 0 (0-3.26)g/day/patientl and increase calcium carbonate dosage (1.95 0.92 vs. 2.98 2.14g/day/ patient) after conversion significantly (P<0.05). The frequency of peritonitis was similar in LCD and SCD period. In conclusion, low calcium dialysate is useful in diminishing aluminum-containing phosphate binder dosage and increasing calcium carbonate dosage to maintain a similar phosphate value. Its effects on renal osteodystrophy remain to be assessed.