Effects of systemic pH on calcium regulating hormones and bone

Acetate free citrate-containing dialysate increase intact-PTH and BAP levels in the patients with low intact-PTH

BACKGROUND

Recently, acetate-free citrate containing dialysate (A(-)D) was developed. We have already reported about the significant effect of A(-)D on metabolic acidosis, anemia, and malnutrition in maintenance hemodialysis (MHD) patients. In this study, we compared the effect of A(-)D and acetate containing dialysate (A(+)D) on serum calcium and intact-parathyroid hormone (int-PTH) levels.

METHOD

Single session study: Seventeen patients were treated with A(+)D in one session and also treated with A(-)D in another session. Serum levels of pH, HCO3-, total (t)-calcium, ionized (i)-calcium, and int-PTH were evaluated at the beginning and the end of each session. Cross over study: A total of 29 patients with MHD were treated with A(+)D for 4 months, switched to A(-)D for next 4 months, and returned to A(+)D for the final 4 months.

RESULTS

In single session study, serum i-calcium and t-calcium levels significantly increased, and int-PTH levels decreased after HD with A(+)D, whereas HD with A(-)D did not affect iCa and int-PTH. In cross over study, if all patients were analyzed, there was no significant difference in serum int-PTH or bone alkaline phosphatase (BAP) levels during each study period. In contrast, in the patients with low int-PTH (<60 pg/mL), serum levels of int-PTH and BAP were significantly increased during the A(-)D, without significant changes in serum t-calcium or i-calcium levels.

CONCLUSION

A(-)D containing citrate could affect calcium and PTH levels, and, in 4 month period of crossover study, increased int-PTH levels pararelled with increasing BAP levels, exclusively in MHD patients with low int-PTH levels.

Trabecular bone remodeling and bone mineral density in the adult cat during chronic dietary acidification with ammonium chloride

Ammonium chloride (NH4Cl) is used as a urinary acidifier in the treatment and prevention of feline urologic syndrome. It is reported to cause alterations in calcium and bone metabolism in humans, dogs, and rats. Adult cats with normal renal function were fed 1.5% NH4Cl for 6 months to study the effects of chronic dietary acidification on trabecular bone remodeling of the iliac crest and bone mineral density (BMD) of lumbar vertebral trabecular bone and femoral cortex. Histomorphometric analyses of iliac crest biopsies were performed before and after treatment. Static and dynamic parameters of bone resorption and formation were determined. Single-energy quantitative computed tomography (SEQCT) was used to measure lumbar trabecular and femoral cortical BMD. There were no significant treatment effects in iliac crest trabecular bone remodeling or BMD of the vertebrae and femora. Bone remodeling activity decreased with time in both acidotic and control cats. Vertebral BMD increased with time in both groups of cats, whereas no change was seen in the femora. Thus, chronic dietary acidification for 6 months with therapeutic levels of NH4Cl produced no significant changes in trabecular bone remodeling or bone mineral density in adult cats.