Multiple myeloma with hypercalcemia and chloride resistant metabolic alkalosis

This report describes a novel presentation of chloride resistant metabolic alkalosis in a patient with hypercalcemia related to Multiple Myeloma (MM). A 51-year-old male with newly diagnosed MM presented with widespread skeletal involvement, calcium (Ca(+2)) of 18 mg/dL, phosphorous (PO4) of 6 mg/dL, serum bicarbonate (HCO3) of 37 mEq/L, and serum creatinine (Cr) of 2.6 mg/dL Other causes of metabolic alkalosis such as vomiting, diuretics, alkali ingestion, mineralocorticoid excess and hypokalemia were excluded. Hypercalcemia and metabolic alkalosis were only partially corrected after rehydration, calcitonin and steroids. Subsequent treatment with zoledronic acid resulted in resolution of hypercalcemia and correction of metabolic alkalosis.The chloride resistant component of metabolic alkalosis was most likely related to extensive release of Ca(+2), carbonate and phosphate from bone by activated osteoclasts with inhibited osteoblastic activity. The additional reduction in glomerular filtration rate due to MM, contributed to a triad mimicking Calcium-Alkali syndrome.