Low-calcium dialysate stimulates parathormone secretion and its long-term use worsens secondary hyperparathyroidism.
The long-term clinical effects of the use of a low calcium concentration in the dialysate are largely unknown. For this reason, the influence of low-calcium dialysate on parathyroid hormone (PTH) secretion in hemodialysis patients and its long-term effect on the severity of secondary hyperparathyroidism were studied. In 35 hemodialysis patients, the dialysate calcium concentration was lowered from 1.75 to 1.25 mmol/L. Twelve months later, serum iPTH levels increased significantly from 18.6 to 33.2 pmol/L and so did alkaline phosphatase levels, from 210 to 330 IU/L, without significant changes in serum calcium or phosphorus levels. Hemodialysis with low-calcium dialysate (1.25 mmol/L) induced a net calcium loss in 10 patients, without modifications in ionized serum calcium levels. In addition, mean serum iPTH increased 20% over baseline levels, reaching the maximal level at 30 min after the start of hemodialysis with low-calcium dialysate. In contrast, mean serum iPTH levels drop dramatically at 30 min of hemodialysis with high-calcium dialysate (1.75 mmol/L). It was concluded that low-calcium dialysate worsens secondary hyperparathyroidism in hemodialysis patients, probably by inducing a negative calcium balance and causing repetitive stimulation of PTH secretion in each dialysis. The maintenance of normal serum calcium levels could be due to PTH-induced calcium mobilization from bone.
Fernández
E
E
Nephrology Service, University Hospital Arnau de Vilanova, Lleida, Spain.
Borràs
M
M
Pais
B
B
Montoliu
J
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D000469:Alkaline Phosphatase / Q000097:blood; D002118:Calcium / Q000032:analysis* / Q000097:blood; D005260:Female; D015312:Hemodialysis Solutions / Q000009:adverse effects* / Q000737:chemistry*; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood / Q000378:metabolism*; D010758:Phosphorus / Q000097:blood; D006435:Renal Dialysis / Q000009:adverse effects; D013997:Time Factors
D015312:Hemodialysis Solutions; D010281:Parathyroid Hormone; D010758:Phosphorus; D000469:Alkaline Phosphatase; D002118:Calcium