Introduction:
Dialysate calcium is a critical component in the Parathyroid hormone (PTH) level of a dialysis patient. Over the decades dialysate calcium has been increased from 1.25mmol/l to 1.5mmol/l and 1.75mmol/L to decrease incidence of intra-dialysis hypotension and easier control of PTH. However, recently there has been more concern for the higher dialysate calcium leading to adynamic bone disease with suppressed PTH and vascular calcification due to calcium loading from the higher dialysate calcium and low PTH levels not allowing buffering into the bone. At present the right dialysate calcium is uncertain. In India, most dialysis centers use 1.75mmol/L dialysate calcium. We noted a high percentage of our patients with PTH < 150 and hence decided to switch most of our patients dialysate calcium from 1.75mmol/l to 1.25mmol/l. Here we describe the changes in PTH for these patients.
Methods:
Retrospective review of our dialysis patients was performed for dialysis patients who initiated dialysis at our center or transferred to our center between July 2022 – Dec 2023. They had to have dialyzed at our center for atleast 6 months to be included in the study and they were excluded if they did not have atleast 2 PTH readings. Dialysate calcium was noted for all. Their PTH readings were classified as Start (on initiation or transfer to our unit), 1.75mmol/l (3 months), 1.25mmol/l (at 3 months), 1.25mmol/l (at 6 months), 1.25mmol/l (at > 6 months). The percentage of patients in the different level of PTH < 150, 150-600 and > 600 were calculated
Results:
52 dialysis patients met the inclusion criteria with a mean age of 57 years, with 37 (71%) male and 15 (29%) females. The distribution of PTH at the different time points is in Table 1. Average PTH at initiation or transfer to our unit was 262. The average was 370 at the start for the 27 patients who then were on 1.75mmol/l and their PTH decreased to 191. After switch to 1.25mmol/L the PTH stabilized to 187 and then increased to 263 and then 445. The percentage of patients who had PTH < 150 increased from 33% to 63% while on 1.75mmol/l and decreased to 38% by 3 months on 1.25mmol/l and further decreased to 31% by 6 months and 27% for those beyond 6 months.
Table 1: PTH distribution by dialysate calcium and duration.
Conclusions:
Our study shows that dialysate calcium of 1.75mmol/L leads to a high percentage of patients with PTH< 150, likely putting them at high risk for adynamic bone disease. Shifting to a dialysate calcium of 1.25mmol/l decreases the number of patients with PTH < 150, though does not eliminate it.With longer duration of dialysis with 1.25mmol/l some patients do have PTH > 600 and will need additional treatment for managing hyperparathyroidism. It is time to shift the pendulum and lower dialysate Calcium to avoid suppressed PTH and adynamic bone disease in our dialysis patients.
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.