The Negative Ca²⁺ Balance Is Involved in the Stimulation of PTH Secretion

Abstract

The low calcium (Ca²⁺) dialysate have been developed to diminish the risk of hypercalcemia with the administration of active vitamin D and Ca²⁺ carbonate as phosphate binder. Today, increasing numbers of hemodialysis (HD) patients have been on the low Ca²⁺ dialysate (Ca²⁺ = 2.5 mEq/l). However, the clinical consequences of a negative calcium net-balance which may be induced by the use of low Ca dialysate are not well evaluated. In the present study, we explored the effects of low Ca²⁺ dialysate on the calcium balance and the PTH secretion. Eighty one chronic HD patients (male/female: 47/34; mean age: 60.2 ± 1.5 years; mean HD periods: 11.1 ± 0.8 years) who had been dialyzed with 3.0 mEq/l Ca²⁺ dialysate were studied. All patients were transferred to the low Ca dialysate, which actually brought about a negative net-balance in Ca (mean: –94.5 mg) and an increase in serum intact PTH levels (mean: +23.7%: p = 0.03) during a single HD session. However, no changes in serum ionized Ca²⁺ were found in spite of negative Ca²⁺ balance. One month after change to the low Ca²⁺ dialysate (total 12 sessions in each case), serum intact PTH levels increased significantly (186.7 ± 19.5 vs. 216.2 ± 21.9 pg/ml: p = 0.01) in spite of the fact that no changes were found in serum ionized Ca²⁺, Pi and Mg. This result indicates that the negative Ca²⁺ balance during low-Ca²⁺ hemodialysis-stimulated PTH secretion, which offset the decrease of serum Ca²⁺; a trade-off phenomenon between negative Ca balance and PTH. This suggests that low Ca²⁺ dialysate may exaggerate the progression of secondary hyperparathyroidism.

Low calcium dialysate combined with CaCO3 in hyperphosphatemia in hemodialysis patients

“…Several patients did not tolerate long-term LCD treatment as their PTH level increased too rapidly; the PTH levels of the majority of the subjects increased only slightly and reached a stable level after 3–6 months, which is consistent with the results of related literature (21). The reason for this occurrence may be the oral administration of CaCO 3 during LCD treatment, which allows the PTH level to remain stable.…”

“…Therefore, the imbalance in Ca 2+ caused by the application of LCD may significantly stimulate the secretion of PTH (17). One study (18) confirmed that LCD alone significantly increases serum PTH, revealing that the increase of PTH is related to the decline of blood Ca 2+ and that PTH is restored to the level in the previous dialysis prior to the next dialysis. Ferreira et al (19) performed a one-year study of hemodialysis patients and identified that the iPTH levels significantly increased.…”

Randomized trial comparing pulse calcitriol and alfacalcidol for the treatment of secondary hyperparathyroidism in haemodialysis patients

“…There was no complication of this approach and calcium levels were in desired ranges through the study. However, PTH levels may be acutely increased by using low‐dialysate calcium 26,27 . Finally, this was a small sample size, however, there is no previous study comparing these drugs with adjusted dose according to the pharmacokinetic study.…”

Effects of low dialysate calcium concentration on health-related quality of life in hemodialysis patients

“…Many studies have reported that a low calcium dialysate concentration increased serum i-PTH levels, 3,4,[13][14][15][16] while some studies of a low calcium dialysate concentration reported that high doses of calcium carbonate (mean dose, 6.2-10.5 g/day) could achieve adequate control of serum i-PTH and phosphorus levels. 2,5 We used a total calcium carbonate level of 4.1 g/day and the increment in total calcium carbonate was 0.5 g/day.…”