Syndrome of inappropriate antidiuretic hormone due to multiple myeloma.

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) has been linked to many malignancies. However, literature noting multiple myeloma as a possible cause of SIADH is lacking. Although there is a plethora of literature reporting multiple myeloma induced spurious hyponatremia, our review revealed only one case report, in 1983, describing multiple myeloma induced SIADH. Here we report another case of multiple myeloma induced SIADH, where secondary causes of SIADH, including pseudohyponatremia, were ruled out.