Renal Salt Wasting Syndrome due to Carboplatin in a Patient with Lung Cancer.
A 40-year-old woman with lung cancer had multiple episodes of hyponatremia whenever she had chemotherapy with cisplatin plus etoposide and/or carboplatin plus etoposide over the last year. Although she
had been diagnosed as having Syndrome of Inappropriate Secretion of Antidiuretic Hormone, based on a
multidisciplinary assessment, a diagnosis of Renal Salt Wasting Syndrome possibly due to carboplatin was made, and after
completion of intravenous treatment with isotonic saline, hyponatremia resolved, and she was discharged uneventfully.
Cisplatin is well known for causing renal toxicity via proximal tubular damage, some cases of which present as RSWS. However, RSWS is extremely rare with carboplatin. The differential diagnosis between RSWS and SIADH for
hyponatremic patients is sometimes difficult because of similarities in their clinical features, but careful consideration is needed to make the correct diagnosis because their treatments are diametrically opposed.
Hyponatremia has a large differential diagnosis and is a critical issue in cancer patients. The Syndrome of Inappropriate Secretion of Antidiuretic Hormone is a well-known cause of hyponatremia, while physicians generally overlook Renal Salt Wasting Syndrome.
This reflects the difficulty of differentiating between SIADH and RSWS based on limited clinical or laboratory findings. This case illustrates a useful way of discriminating between these two disorders and also shows that carboplatin is an extremely rare cause of RSWS.
Pulm Res Respir Med Open J. 2014; 1(1): 9-12. doi: 10.17140/PRRMOJ-1-102
