Hypophosphatemic encephalopathy in a CAPD patient

Severe refeeding hypophosphatemia has been reported in infants and adults on continuous ambulatory peritoneal dialysis. We report an episode of transient encephalopathy and cardiac suppression in a diabetic, malnourished end-stage renal disease patient undergoing peritoneal dialysis with a glucose-based solution, which was associated with severe hypophosphatemia. Further investigation revealed an adynamic bone disease. The potential factors precipitating this episode of hypophosphatemia are discussed.

Different Routes Bridging Calcium in Japanese Hemodialysis Patients

There is growing evidence that not only serum calcium concentration but also excess calcium load is associated with vascular calcification and mortality in hemodialysis patients. Calcium load in hemodialysis patients cumulatively comes from three different routes: oral intake of calcium including calcium-based phosphate binders, traffic of calcium from/to dialysate, and calcemic action of vitamin D. The K/DOQI guidelines recommend sevelamer hydrochloride instead of calcium-containing phosphate binders to control serum phosphate concentration. However, in Japan, both kinds of phosphate binders are used concomitantly, mainly because Japanese patients are prone to a higher incidence of sevelamer-associated adverse events such as gastrointestinal symptoms. Regarding the calcium concentration of dialysate (D-Ca) in Japan, 3.0 mEq/L is more popular than 2.5 mEq/L. Calcium loaded through 3.0 mEq/L dialysate may lead to metastatic calcification rather than to bone formation because serum phosphate concentration rebounds several hours after the end of each hemodialysis session when plasma pH is still high. In contrast, use of 2.5 mEq/L dialysate may result in an unfavorable increase of intact parathyroid hormone particularly when the amount of oral calcium intake is reduced. Although a higher dose of vitamin D is required to counteract the stimulation of parathyroid glands, hypercalcemia is less likely with 2.5 mEq/L dialysate. As the new K/DOQI guidelines are released, it is time to discuss the appropriate D-Ca as well as doses and kinds of phosphate binders and vitamin D for the comprehensive management of Japanese hemodialysis patients.

Calcium balance during pulse alfacalcidol therapy for secondary hyperparathyroidism in CAPD patients treated with 1.0 and 1.25 mmol/L dialysate calcium

Hypercalcemia frequently occurs in continuous ambulatory peritoneal dialysis (CAPD) patients treated with calcium carbonate and vitamin D metabolites. To reduce the incidence of this complication, it has been proposed to use dialysate solutions with a low calcium concentration. However, there is concern that these solutions may lead to a negative calcium balance. We measured calcium balance in 13 CAPD patients with secondary hyperparathyroidism who were treated with calcium carbonate and alfacalcidol, 2 microg twice weekly, while using 1.0- (1.0 group) and 1.25-mmol/L (1.25 group) dialysate calcium solutions. Calcium absorption was measured after the administration of Ca47. Results for the 1.0 (n = 6) and 1.25 (n = 7) groups included fractional calcium absorptions of 0.14 (range, 0.09 to 0.27) and 0.08 (range, 0.03 to 0.40; P = not significant [NS]) and calcium absorptions of 380 +/- 92 and 331 +/- 83 mg/d (P = NS). Dialysate calcium losses were 93 +/- 20 and 91 +/- 26 mg/d, and total calcium losses (dialysate and urine) were 106 +/- 16 and 108 +/- 40 mg/d (P = NS). Calcium balance was positive in all patients (274 +/- 92 and 223 +/- 65 mg/d; P = NS). These data suggest that the use of 1.0- and 1.25-mmol/L calcium solutions in conjunction with calcium carbonate and pulse alfacalcidol therapy is associated with a positive calcium balance in CAPD patients.

Low dialysate calcium in continuous ambulatory peritoneal dialysis: a randomized controlled multicenter trial. The Peritoneal Dialysis Multicenter Study Group

Hypercalcemia is a common complication in continuous ambulatory peritoneal dialysis (CAPD) patients treated with calcium-containing phosphate binders and using the standard dialysate calcium concentration of 3.5 mEq/L (SCa). Lowering the dialysate calcium was proposed to overcome this problem. The current randomized controlled multicenter study was designed to investigate efficiency and safety of a low calcium dialysate (2.00 mEq/L; LCa) compared with SCa (3.5 mEq/L) in CAPD patients. After an 8-week run-in period, 103 stable CAPD patients, 68 men, 35 women, aged 54.5 years (range, 20 to 77)) were randomly allotted to treatment with either LCa or SCa. All patients received calcium carbonate as oral phosphate binder to achieve serum phosphate levels < 6.2 mg/dL. If persistent hypercalcemia arose, CaCO3 was replaced by Al(OH)3 until normocalcemia was achieved. All patients received 0.25 microgram calcitriol/d. Parameters monitored included total and ionized serum calcium, serum phosphate, phosphate binder intake, incidence of hypercalcemia, serum aluminium, intact parathyroid hormone (1,84PTH), osteocalcin, alkaline phosphatase, bone mineral density and hand skeletal x-ray. Primary end points were (a) number of hypercalcemic episodes, (b) tolerated doses of calcium-containing phosphate binders, and (c) 1,84PTH. After 6 months of therapy, total and ionized calcium were lower in LCa patients (total Ca:9.6 v 10.08 mEq/L, P = 0.005; iCa: 4.76 v 5.15 mg/dL; P = 0.013). In the LCa group, significantly fewer episodes of hypercalcemia were recorded (total S-calcium > 10.8 mg/dL: LCa 24 v SCa 86 episodes; P < 0.005). Use of LCa permitted the administration of more CaCO3 (mean daily tablet number: LCa, 5.9 v SCa, 4.2; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary and pharmacotherapeutic considerations in the management of renal osteodystrophy

Renal osteodystrophy is an early complication of renal failure associated with significant morbidity. An understanding of dietary management and pharmacotherapeutic prevention and treatment of this condition is essential for members of the nephrology interdisciplinary team. The purpose of this article is to summarize the practical considerations of dietary and pharmacological management in renal osteodystrophy. Experientially based information from a 300-patient dialysis center is provided within specific guidelines, including sample diets and a pharmacotherapeutic algorithm. Treatment-outcome goals for serum phosphorus, serum calcium, and parathyroid hormone are discussed. Patient-specific factors are also discussed, including phosphorus load, calcium load, vitamin D supplementation, and dialysis treatment parameters.