[The influence of short-term magnesium carbonate treatment on calcium-phosphorus balance in dialysis patients].

INTRODUCTION: The phosphate-binders presently used in the treatment of calcium-phosphorus disorders in dialysis patients remain a crucial element of cardio-vascular protection. The aim of the study was to assess short-time magnesium carbonate treatment efficacy in hemodialysis patients with hyperphosphatemia.

MATERIAL AND METHODS: The study involved 64 participants (32 male and 32 female) aged 29-84 years, with end-stage renal disease, hyperphosphatemia (> 1.78 mmol/l), dialysis 3 times a week, mean session time 4 hours 15 minutes. All the patients were divided into three groups: I--30 patients treated with magnesium carbonate 3 x 1 g; group II--10 patients treated with sevelamer hydrochloride 0.8 g--3 x 2 tabl (3 x 1.6 g); group III--24 patients treated with calcium carbonate 3 x 2 g. Participants were categorized randomly to groups I and II and to group III only patients with decreased serum calcium concentration (< 2.1 mmol/1) were assigned. The doses stayed constant within 12 weeks of therapy.

RESULTS: In group treated with magnesium carbonate after 3 months of the treatment the decrease of plasma parathormon (iPTH) from 526.1 +/- 463.3 to 443.2 +/- 223.1 (pg/ml), calcium (Ca) from 2.4 +/- 0.2 to 2.3 +/- 0.1 (mmol/1); the highest reduction of phosphate (P) 2.1 +/- 0.5 to 1.6 +/- 0.4 (mmol/1) and calcium phosphate product (Cax P) from 4.6 +/- 2.3 to 3.5 +/- 1.1 (mmol2/ l2) were observed. In group II, iPTH slightly increased from initial 425.26 +/- 192.5 to 445.6 +/- 222.3 (pg/ml); serum calcium decreased from 2.23 +/- 0.17 to 2.0 +/- 0.2 (mmol/l); phosphates dropped from 2.35 +/- 0.43 to 2.0 +/- 0.3 (mmol/l) and Ca x P index from 5.1 +/- 1.2 to 4.1 +/- 0.7 (mmol2/l2). In group treated with calcium carbonate iPTH decreased from 308.2 +/- 196.6 to 301.9 +/- 188.5 (pg/ml). Calcium, phosphate and Ca x P dropped during the treatment from 2.06 +/- 0.23 to 2.05 +/- 0.2 (mmol/l), 2.17 +/- 0.36 to 1.86 +/- 0.45 (mmol/l) and from 4.7 +/- 0.8 to 3.7 +/- 0.9 (mmol2/l2), respectively. Calcium-phosphorus disorders were normalized to actual guidelines only in participants treated with magnesium carbonate.

CONCLUSIONS: Magnesium carbonate seems to be the effective treatment of calcium-phosphorus disorders in hemodialysis patients. However its administration, similarly to other non-calcium phosphate-binders, is limited and dedicated to patients with normal serum calcium concentration.