# Syndrome of inappropriate antidiuresis secondary to multiple myeloma: a case report and literature review

## TL;DR

A case report shows that multiple myeloma can cause inappropriate antidiuresis, a condition that leads to low sodium levels in the blood.

## Contribution

This case highlights multiple myeloma as a rare but possible cause of syndrome of inappropriate antidiuresis.

## Key findings

- Hyponatremia was the primary symptom leading to the diagnosis of SIAD and later multiple myeloma.
- Anti-myeloma therapy corrected hyponatremia upon achieving a Very Good Partial Response.
- The case suggests a potential link between multiple myeloma and SIAD that requires further investigation.

## Abstract

The syndrome of inappropriate antidiuresis (SIAD) has been associated with various diseases. However, to our knowledge, only a few studies have reported multiple myeloma (MM) as a potential cause of SIAD. We report a case where hyponatremia served as the primary clinical manifestation, diagnosed with SIAD and subsequently confirmed as multiple myeloma. Following anti-myeloma therapy, the hyponatremia was successfully corrected upon achieving a hematologic response classified as Very Good Partial Response (VGPR). This case contributes to an uncommon etiology of SIAD, highlighting the potential association between SIAD and multiple myeloma, and underscores the need for further research into this connection.