Effects of cimetidine on parathyroid hormone metabolism

Renal osteodystrophy

Over the past decade important advances in our understanding of the pathophysiology and treatment of renal osteodystrophy have been made. In particular, the role of calcitriol deficiency in the genesis of hyperparathyroidism in early renal failure is now better understood. So too are the effects of aluminium on bone, and whereas the more florid aluminium related disease is now unusual the more subtle effects of aluminium are now being appreciated. There is still a major problem in the long-term treatment of hyperparathyroid bone disease. The reasons why parathyroid gland proliferation continues to occur on dialysis therapy require a better understanding of cellular events regulating hormone production and parathyroid cell replication. The case for early intervention with vitamin D is now strong but whether such an approach materially influences the long-term outcome is not yet established. Changes in the approach to treatment and in the modalities used for renal replacement therapy will continue to modify the nature of the bone disease.

Long-term effects of histamine H2-receptor antagonists on serum parathyroid hormone in chronic renal failure

We assessed the effects of ranitidine and cimetidine (histamine H2-receptor antagonists) on the serum concentrations of parathyroid hormone (PTH) in 22 patients with end-stage chronic renal failure. Treatment for 3 months induced a significant decrease in serum concentrations of PTH determined by radioimmunoassay directed at the mid portion of the PTH molecule. In contrast, significant increases were noted using an assay directed at the amino-terminal portion, whereas no change was noted with a carboxy-terminal assay. No significant changes in serum calcium, phosphate and alkaline phosphatase were noted after treatment with either agent, but serum concentrations of osteocalcin increased significantly. We conclude the H2-receptor antagonists do not favourably influence the natural history of hyperparathyroid bone disease in patients with end-stage chronic renal failure.

Cimetidine does not correct circulating calcium and parathyroid hormone in primary hyperparathyroidism

Thirteen patients with primary hyperparathyroidism were treated for 4-8 weeks with the H2-blocker cimetidine at a daily dose of 1 g. The drug had no effect on the serum concentrations of calcium or parathyroid hormone, nor did any of the patients improve clinically during the period of treatment. The recently reported efficacy of cimetidine in primary hyperparathyroidism is strongly questioned by the present results.