Hypercalcaemia and azotaemia in multiple myeloma--clinical and biochemical parallels.

109 patients with multiple myeloma were studied. In 35 (32%) of them calcium level was elevated above 2.65 mmol/l and increased significantly with the clinical stage of the disease. A various degree of nitrogen retention, which was not statistically significantly dependent on the clinical stage, was found in 65 (56%) patients. There was a moderate positive correlation (r = +0.46) between the renal failure and Bence Jones proteinuria. In 27 patients, 77% of the hypercalcaemic and 44% of the azotaemic patients, both the calcium level and azotaemia were increased. In the patients with reversible and partially reversible azotaemia the occurrence of hypercalcaemia as well as the absolute values of serum calcium and creatinine showed parallel dynamics after treatment. The progression of calcaemia with the increase of nitrogen retention is a characteristic feature of renal failure in multiple myeloma. Hypercalcaemia and azotaemia are mutually interacting pathogenetic factors and the correction of increased calcium level is a must in modern therapeutic strategies.