[Combined therapy with calcitonin and high doses of active vitamin D3 metabolites in uremic hyperparathyroidism].

Active vitamin D3 pulse therapy effectively suppresses parathormone (PTH) synthesis in uremic hyperparathyroidism but high serum levels of calcitriol achieved can induce direct osteoclastic resorption and block bone formation. Therefore we found it interesting to examine whether an addition of the osteoclast inhibitor, calcitonin (CT), could reduce those unwanted effects. 75 hemodialysis patients with at least 5-fold 1-84 PTH serum level elevation were divided into 4 treatment groups: I (n = 19)-CT and 1 alpha-OH-D3; II (n = 20)-CT; III (n = 19)-1 alpha-OH-D3 (n = 10) or 1.25 (OH)2D3 (n = 9) alone; IV (n = 17)-none of these drugs. CT (200 IU) and 1 alpha-OH-D3/1.25(OH)2D3 (up to 5 micrograms) were given 3 times a week. Dialysate Ca was 1.40-1.45 (Group I, III) or 1.95-2.00 mmol/l (Group II, IV). Within 8 months serum 1-84 PTH fell by 75% (p < 0.001) in Group I and by 77% (p < 0.001) in Group II, serum Ca increased by 0.22 +/- 0.05 mmol/l in Group I (p < 0.005) and by 0.25 +/- 0.05 mmol/l in Group III (p < 0.005), alkaline phosphatase activity decreased by 35% in Group I (p < 0.01) and 31% in Group III (p < 0.005) whereas in Groups II and IV no significant changes were noted. In Group III no differences between patients taking 1 alpha-OH-D3 or 1.25 (OH)2D3 were observed. The significant reduction of serum hydroxyproline (37%; p < 0.001) was seen only in Group 1. The increase in bone mineral density (BMD) measured by dual-energy X-ray absorptiometry was greater in Group I than in Group III (p < 0.05). In Group II the effect was mostly insignificant, whereas in Group IV a substantial decrease (p < 0.001) in BMD was observed. These data suggest that combined therapy with CT and oral 1 alpha-OH-D3 pulses is more effective than pulses alone in inhibiting bone resorption and in increasing BMD in hemodialysis patients with uremic hyperparathyroid bone disease.