Low and High Turnover Bone Disease in Continuous Ambulatory Peritoneal Dialysis: Effects of Low-Ca + Peritoneal Dialysis Solution

Calcium carbonate (CaCO3) is an effective phosphate (P04) binder in uremics, and its use reduces aluminum (AI) intake. By maintaining high serum Ca2+, it decreases serum parathyroid hormone (PTH) levels. Hypercalcemia, however, often limits the dosage.

In order to evaluate the effects of a low-Ca peritoneal dialysis solution (PDS) (1.25 mmol/L) on Ca metabolism, we studied the following in 12 continuous ambulatory peritoneal dialysis (CAPD) patients with hypercalcemia (6 with low PTH levels, low-turnover bone disease, group 1, and 6 with high PTH levels, high-turnover bone disease, group 2, documented by bone biopsies): serum Ca2+; serum PTH; bone morphology. The follow-up was 12 months.

Results show that in both groups within the third month there was a decrease in serum Ca2+. In group 1 serum PTH increased, reaching the norm, and In group 2 it further Increased exceeding the norm. Because In both groups serum Ca2+ was normal, It was possible to increase oral CaC03 (10.5±2.5 g/day) to control P04 levels and to stop AI gels. In group 2, In order to avoid the further rise of serum PTH, the low-Ca PDS was supplemented with 2 μg/day of 1,25(OH)2D3 (vitamin D3); this was followed by a reduction In serum PTH with no increase in Ca2+ and P04.

The use of low-Ca PDS may be useful In preventing hypercalcemia In CAPD patients treated with high oral doses of CaC03 and in improving low-turnover bone disease, while low-Ca PDS supplemented with vitamin D3 improves high-turnover bone disease.

Mechanical Cardiopulmonary Resuscitation Choice of Patients on Chronic Peritoneal Dialysis

Fifty-five adult patients (5 women, 50 men) on chronic peritoneal dialysis, mostly continuous ambulatory peritoneal dialysis (CAPD), for 2 to 155 mon were asked whether or not they wanted to have mechanical cardiopulmonary resuscitation (CPR) in case of sudden death. Thirty-five patients (65%) opted for CPR and 20 (36%) declined. Statistically, sex (although the number of women interviewed was too small for a valid sample) and duration of dialysis had no effect on choice of CPR, whereas older age, the presence of diabetes, advanced medical disability, and advanced socioeconomic disability were associated with a tendency to decline CPR. Among the 10 patients who had CPR, 5 developed flail chest, 4 had multiple rib fractures, and only 1 had no chest wall trauma from CPR. Two patients left the hospital alive. One third of the patients on chronic peritoneal dialysis do not want CPR. Advanced age, diabetes, and poor medical and socioeconomic states predispose peritoneal dialysis patients to decline CPR.

Continuous Ambulatory Peritoneal Dialysis Connection Systems

The history of the various connection systems proposed and tried during the first 15 years of clinlcal application of continuous ambulatory peritoneal dialysis (CAPD) is reviewed.

In order to understand the reasons for their success or lack of success, the main technical and operating characteristics regarding their efficacy In preventing peritonitis are examined in detail, together with a range of other pros and cons (I.e., reliability, simplicity, ease of use, cost, aesthetlcal aspects).

The result Is an updated state-of-the-art review In the field of CAPD connectology, with a look at future trends.

Can Low-Calcium Peritoneal Dialysis Solution Safely Replace the Standard Calcium Solution in the Majority of Chronic Peritoneal Dialysis Patients?

Objective

To evaluate the use of low-calcium solution as the standard solution in chronic peritoneal dialysis patients.

Design

Prospective long-term follow-up study over a one-year period.

Setting

University hospital.

Interventions

The change of the calcium concentration of the dialysate from 1.75 mmollL to 1.25 mmollL.

Main Outcome Measures

Serum calcium and phosphorus concentration and intact parathyroid hormone (iPTH).

Patients

Fifty normo and hypercalcemic patients using the standard 1.75 mmollL calcium solution.

Results

Serum ionized calcium (iCa) decreased significantly during the first six months, resulting in a significant increment of iPTH (baselinevalue: 0.9 79, median 9.4 pmollL; at six months: 1.1 -111, median 20.6 pmollL; p < 0.05). In 28 patients completing the study, iPTH remained significantly elevated, despite high normal iCa. At similar changes of iCa, patients with baseline iPTH > 20 pmollL showed a significantly higher increase in iPTH than patients with low iPTH (24.0 vs 5.0; p < 0.01), despite a more than doubled dose of alfacalcidol and calcium carbonate (mean dose of 1580 increased to 3277 mg/day). During the follow-up, 21 episodes of hypercalcemia were observed. Phosphorus control was adequate.

Conclusions

Low-calcium solution cannot be used as a standard solution, especially in patients with iPTH levels indicating mild or severe hyperparathyroidism, because in these patients iPTH may rise further.

Measurement of Serum Ionized Magnesium in Capd Patients

Objective

To evaluate the magnesium status of continuous ambulatory peritoneal dialysis (CAPD) patients using a new method for assessing the level of the ionized fraction a serume magnesiumy.

Design

Serum ionized magnesium was measured in CAPD patients using the ion-selective electrode for Mg2+.

Setting

The Dialysis Unit of Tampere University Hospital.

Patients

Twenty -six patients on CAPD (age: 21 -81 years, mean 54 ± 16 years; duration of CAPD: 3 -52 months, mean 13 months), and 26 sex and age-matched healthy controls.

Results

Both serum ionized magnesium (0.73 ± 0.11 mmol/L vs 0.56 ± 0.07 mmol/L, p < 0.001) and total magnesium (1.11 ± 0.22 vs 0.81 ± 0.08 mmol/L, p < 0.01) were higher in CAPD patients than in sex and agematched controls. The ionized magnesium fraction of total magnesium was slightly lower in dialysis patients in spite of the fact that 16/26 patients had serum albumin less than 36 g/L. Hypermagnesemia (mean serum ionized magnesium 0.78± 0.10 mmol/L) was observed in the 13 of 26 patients with 0.75 mmol/L Mg2+ dialysate; those with lower magnesium dialysate (Mg2+ 0.50 mmol/L in 10/26 and Mg2+ 0.25 mmol/L in 3/26) had mean serum ionized magnesium at the upper normal margin (0.69 ± 0.10 mmol/L).

Conclusion

In CAPD patients with Mg2+ 0.5 0.75 mmol/L in their dialysis fluid, both serum ionized and total magnesium concentrations were higher but the ionized/total magnesium ratio was lower than in healthy control subjects. Use of ion-selective electrodes to measure ionized magnesium may be a more useful methodology than measuring total magnesium in the evaluation of magnesium status of CAPD patients, because it is not infuenced by hypoalbuminemia or increased complexed fraction of magnesium often present in dialysis patients.