Controversies surrounding the use of Parathyroid hormone as a marker of bone metabolism in chronic kidney disease(CKD) patients on haemodialysis in Zimbabwe: The way forward

Abstract

Background The progressive loss of renal function in chronic kidney disease (CKD) necessitates the eventual use of dialysis. Renal Osteodystrophy (ROD) is a serious complication of CKD with diverse and non-specific manifestations. Serum biochemical markers such as Parathyroid hormone (PTH) are used worldwide to monitor bone changes in patients on haemodialysis although bone biopsy has remained the gold standard. The use of PTH as a marker for bone changes has however been associated with a lot of controversies linked to its measurement and interpretation. Recommendations from several studies have been proposed on how to improve its clinical robustness in monitoring bone changes of patients on haemodialysis. Evaluation of these recommendations has however not been done extensively especially in Zimbabwe. Objectives To determine which serum marker(s) of bone offers the best diagnostic and monitoring sensitivity in CKD patients on haemodialysis before and during three months on haemodialysis. Materials and methods A short prospective study was carried out on CKD patients admitted on haemodialysis at three selected Renal Units (Parirenyatwa, Chitungwiza, PSMI). A total of 32 patients aged 22-75 years (Mean 50.5 ± 16.5 years) were randomly selected. Study group was divided into viii those who had been on dialysis for more than three months (Group 1) and those who had been enrolled to start haemodialysis (Group 2). Serum levels of calcium, phosphate, PTH and bALP were determined over a three month period. Results There were significant increases in bALP (P=0.02) in group 1. A 69.6% increase in mean phosphate was observed in participants using low calcium concentration dialysate fluid.PTH and bALP showed a positive correlation at both 0.05 and 0.01 level of confidence interval using Pearson correlation 2-tailed test. Significant gender differences (P<0.05) in PTH were observed in both groups. Statistically insignificant decreases in PTH were noted for both groups. Conclusion The study findings have shown that PTH levels in an individual patient on haemodialysis fluctuate greatly and therefore diagnosis and monitoring of bone changes in these patients ought to be based on trends rather than a single value of PTH. The study concludes that bALP is indeed a potentially useful bone marker if we are to make headways in resolving some of the issues associated with the use of PTH alone.