HYPERPHOSPHATEMIA IN MULTIPLE-MYELOMA

We report three cases of IgG kappa multiple myeloma with pseudohyperph osphatemia. The patients' serum calcium levels were normal, and the hy perphosphatemia was not related to impaired renal function. No hypopar athyroidism was found, and no exogenous phosphate preparation had been given. Since the hyperphosphatemia was of no obvious clinical or phys iological significance, as evidenced by normal serum levels of 1,25 di hydroxy vitamin D-3, it was diagnosed as spurious and was connected to interference of the paraprotein with the chromogenic assay. In two of the patients major fluctuations in serum phosphate levels were seen, induced by the changes in globulin and paraprotein levels that occurre d during therapy and relapse.