A Case of Myeloma with Hypercalcemia Caused by High Serum Concentrations of both Parathyroid Hormone-related Peptide (PTHrP) and Macrophage Inflammatory Protein-1.ALPHA. (MIP-1.ALPHA.)

A 62-year-old woman was admitted with dry mouth, general fatigue, and severe back pain. Biochemistry examination showed extreme hypercalcemia (21.2 mg/dL). Bone marrow examination was negative, but needle biopsy of a metastatic lung tumor revealed abnormal plasma cells; thus, multiple myeloma stage III-A was finally diagnosed. Serum concentrations of both parathyroid hormone-related peptide (PTHrP) and macrophage inflammatory protein-1alpha (MIP-1alpha) were markedly elevated (PTHrP 7.2 pmol/L, normal 1.1 pmol/L; MIP-1alpha 84.9 pg/mL, normal 46.9 pg/mL). Her myeloma appeared to have simultaneously caused two mechanisms producing hypercalcemia: humoral hypercalcemia of malignancy (HHM) by PTHrP and local osteolytic hypercalcemia (LOH) by MIP-1alpha. Therefore, the combination of two calcium-modulating abnormalities likely aggravated her hypercalcemia.