Endocrine Abstracts

Duloxetine is a serotonin/norepinephrine reuptake inhibitor, prescribed frequently as a first line treatment for Diabetic neuropathy. It is also prescribed for treatment of depression, anxiety disorder and chronic musculoskeletal pain. Hyponatremia is a known adverse effect of most SSRIs including duloxetine and can potentially be life-threatening.Duloxetine induced hyponatremia, however, is relatively rare specially on low doses and is typically seen in the elderly frail patients. We report a case of duloxetine-induced hyponatremia in a 76 year old lady with a background of type 2 diabetes mellitus, hypertrophic obstructive cardiomyopathy, orthostatic hypotension and gradual functional decline and increased frailty. Initially on Fludricortisone and Midodrine for orthostatic hypotension, she was started on Duloxetine by her family doctor for neuropathic pain a week prior to presentation. She was not on diuretics. She then presented to the A&E with frontal headache, confusion, disoreintation and recurrent vomiting. Laboratory findings revealed hyponatremia, low serum and raised urine osmolalities, and increased urine sodium. Her TSH and Cortisol levels were normal. Syndrome of inappropriate antidiuretic hormone was considered and, duloxetine was discontinued. She was treated with fluid restriction, and required intravenous sodium chloride administeration due to hypotension. She responded well to treatment and her confusion and vomiting were improved after correction of sodium. Health care practitioners in general and diabetologist in specific should be aware of the possibility of duloxetine-induced hyponatremia, particularly in elderly frail patients.Elderly people are vulnerable because fluid levels become more difficult for the body to regulate.Close laboratory monitoring is essential after initiation of treatment.