Pseudohypercalcemia in Multiple Myeloma: A Case Report

Hypercalcemia is a common finding in patients with multiple myeloma. Clinical manifestations of hypercalcemia correlate with the level of serum calcium. Ionized serum calcium (Ca (I)) will be increased in true hypercalcemia. In pseudohypercalcemia the Ionized Ca is normal, although binding of calcium to abnormal immunoglobulin causes increased serum calcium level. In the asymptomatic multiple myeloma patients with moderate to severe hypercalcemia, measurement of ionized calcium is critical to exclude pseudohypercalcemia. Here, we describe an asymptomatic 44-year-old man with multiple myeloma who had severe hypercalcemia, but normal serum Ionized Ca level.