Case Report of a Severe Hyponatriemia in a Patient with Renal Cell Carcinoma

Introduction: Around 14% of all cases of hyponatriemia in hospitalized patients is due to underlying tumor-related conditions, with syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and depletional states as two major pathophisiological mechanisms. Case report: A 69-year-old man was commited to our hospital for contituing treatment of mRCC. Phyisical examination at the admission showed sings of extreme malaise, along with confusion, desorientation and weakness. No sings of nephrotic syndrome, cardiac failure, gastrointestinal solute loss or third spacing were found. Hypothyreosis with TSH 112 μIU/ml and T3 1.05 nmol/l was diagnosed and levothyroxine therapy was started with gradual dose increasment. Laboratory tests confirmed stable renal insufficiency with normal kaliemia and severe hyponatriemia refractory to intensive sodium supstitution. Despite the intensive therapy, patient developed cardiorespiratory insufficiency with the lethal outcome on the 13th day of hospitalization. Autopsy was conducted and hypothyroidism was stated as the predominant cause of death. Conclusion: We suggest early detection of endocrine disfunction in patient with mRCC and sunitinib therapy in course.