Severe hyponatremia as an atypical manifestation of pituitary macroadenoma: a case report.

Pituitary macroadenoma most commonly presents with visual disturbances, headache, and other symptoms secondary to adeno hypophyseal hormonal deficiencies and usually alleviates after tumor resection. Pituitary adenomas may be the cause of the syndrome of inappropriate antidiuretic hormone secretion (SIADH) causing hyponatremia, although so far, there have only been a few documented cases. Here, we present a case of pituitary macroadenoma with SIADH and hyponatremia. This case has been reported in line with CARE (CAse REport) criteria. Case presentation: We present a case of a 45-year-old woman who presented with symptoms of lethargy, vomiting, altered sensorium, and seizure. Her initial sodium level was 107 mEq/l, plasma and urinary osmolality were 250 and 455 mOsm/kg, respectively, and her urine sodium level was 141 mEq/day, suggestive of hyponatremia due to SIADH. MRI scan of the brain revealed approximately 14×13×11 mm pituitary mass. Prolactin and cortisol levels were 41.1 ng/ml and 5.65 μg/dl, respectively. Clinical discussion: Hyponatremia can result from various diseases, making it hard to identify the cause. A pituitary adenoma is a rare cause of hyponatremia due to SIADH. Conclusion: Pituitary adenoma rarely might be the cause of SIADH presenting as severe hyponatremia. So, in case of hyponatremia due to SIADH, clinicians should keep pituitary adenoma as well in their differential diagnoses.