Relationships of Serum Magnesium, Calcium, Phosphorus and 1,25(OH)2D3
on Parathyroid Hormone Levels in Hemodialysis Patients

Korean J Bone Metab > Volume 9(1); 2002 > Article

Original Article

Korean Journal of Bone Metabolism 2002;9(1):25-33.

Relationships of Serum Magnesium, Calcium, Phosphorus and 1,25(OH)2D3 on Parathyroid Hormone Levels in Hemodialysis Patients

유지 혈액투석을 받고 있는 환자에서 부갑상선호르몬 분비에 대한 혈청 Magnesium, Calcium, Phosphorus 및 1,25(OH)2D3의 상관성

안선호,이명수,송주흥

원광대학교 의과대학 내과학교실

Abstract

Background
The important factors involved in the regulation of parathyroid hormone (PTH) are calcium (Ca), phosphorus (P) and vitamin D. However, recent studies have suggested that serum magnesium (Mg) may also play a significant role in the modulation of PTH. The aims of this study were to evaluate the relationship between serum magnesium and intact PTH (iPTH) levels and to investigate whether this relationship is independent of other factors, such as calcium, phosphorus, and 1,25(OH)2D3 (vitamin D3).
Methods
We study 66 hemodialysis patients (mean age, 48.8 years; time on dialysis, 72.7 months) undergoing dialysis with a Mg dialysate concentration of 1.5 mEq/L and not receiving vitamin D. Calcium acetate was used as a phosphate binder in all patients. During a 12-month period, Ca, P and total serum Mg were measured every month; iPTH was measured every 3 months; vitamin D3 was measured every 12 months. The mean values of each parameter were computed.
Results
Hypermagnesemia (serum Mg>2.2 mg/dL) was observed in 98% of the patients. Mg and Ca were inversely correlated with iPTH levels (r=-0.27, p<0.05; r=-0.36, p<0.01, respectively). P was positively correlated with iPTH levels (r=0.32; p<0.01). After controlling for the effect of the other variables, only P was positively correlated with iPTH levels. A stepwise multiple regression analysis showed that iPTH levels were predicted by Ca and P levels (multiple r=0.43; p<0.01), whereas Mg and vitamin D3 were not predictive. Patients with inadequately low iPTH level (relative hypoparathyroidism, serum iPTH<150 pg/mL; n=48) showed P, 4.9±1.3 mg/dL; Ca, 9.6±0.9 mg/dL; Mg, 3.4±0.5 mg/dL; vitamin D3, 6.95±3.04 pg/mL. iPTH levels were predicted by only Mg levels in these patients (n=48, multiple r=0.40; p<0.01).
Conclusion
Ca level is the most important factor on PTH regulation in all hemodialysis patients. But, there is a significant inverse relationship between serum Mg and iPTH levels, especially in patients with

Key Words: Calcium, Hemodialysis, Magnesium, Parathyroid hormone, Phosphorus