Despite the fact that approximately 90% of patients with multiple myeloma present themselves with skeletal complaints (1, 2), few studies of bone mineral metabolism in this disease have been reported. Stable calcium studies in multiple myeloma were first reported in the literature by Blatherwick (3) in 1916. Since that time there have been only infrequent reports using balance techniques, or isotopic-tracer methods, or both. Adams, Mason, and Bassett (4) used metabolicbalance techniques to investigate the influence of ACTH on mineral metabolism in three patients with multiple myeloma. Case studies of one or two patients using tracer methods and balance techniques have been reported by Anderson, Emery, McAllister, and Osborn (5), after a therapeutic dose of Ca45; by Spencer, Li, Samachson, and Laszlo (6), who have studied the comparative excretion and retention of Sr85 and Ca45; and recently, by Skoog, Adams, and MacDonald (7), who have reported balance and Sr85-tracer studies in a patient with multiple myeloma treated with various combination of hormones.The study of calcium metabolism in multiple myeloma is of great interest, since diffuse osteoporosis, or osteolytic lesions, or both, are most always present, and hypercalcemia is a frequent (8) cium turnover rates can be estimated. The present report describes studies of calcium metabolism using Ca47 and balance techniques in six patients with multiple myeloma. These studies indicate that the gut is an important source of calcium loss in multiple myeloma, and that the endogenous fecal calcium contributes significantly to the negative calcium balance uniformly found in our patients.
MATERIALS AND METHODSPatients. Three men and three women with multiple myeloma were studied. Their ages ranged from 44 to 65 years. All patients were ambulatory during the entire study. The diagnosis of multiple myeloma was established by abnormalities in serum-protein pattern, bonemarrow examination, and skeletal X rays consistent with that disease. Serum calcium, phosphorus, and alkaline phosphatase were within normal limits in each patient (Table I). The term "untreated," as used in this patient population, refers to the absence of systemic treatment during the 3 months before study.Metabolic balance. All patients were studied in a metabolic-balance ward while they were maintained on fixed metabolic-balance diets, analyzed in triplicate. Four patients received approximately 200 mg Ca and 800 mg P daily, and two received approximately 500 mg Ca and 1,000 mg P daily. All patients were maintained on the specified diets for 8 to 10 days before the balance studies to allow for equilibration to the low-calcium diet and to the metabolic routine. Refused food and emeses were saved, analyzed, and substracted from the daily intake for that period. Fluid intake was kept constant by providing a fixed quantity of distilled water daily. Voided urine specimens were immediately pooled in a refrigerated jar containing 10 ml of concentrated HCl. Stools were separated at intervals of 4 days with ca...
