We report a case with marked serum electrolytic disorders, a syndrome of inappropriate antidiuretic hormone secretion (SIADH) and central pontine myelinolysis (CPM) following systemic chemotherapy using cisplatin (CDDP).
The patient was a 66-year-old man with squamous cell carcinoma of the tongue and floor of the mouth at the clinical stage rT4N0M0. He was receiving combination chemotherapy with CDDP, docetaxel and 5-FU. Marked hyponatremia appeared within 2 days of the chemotherapy. Furthermore, increases in the antidiuretic hormone level, plasma osmolality, urinary osmolality and urine Na concentration were identified. Finally, SIADH was diagnosed. Water intake was limited and supplementary Na was provided, improving hyponatremia. CPM appeared following correction of the serum Na concentration, but resolved spontaneously over time.
We consider that serum sodium should be measured frequently after chemotherapy including CDDP and that an early response is important when hyponatremia occurs.