Vasopressin-induced hyponatremia in an adult normotensive trauma patient: A case report

Abstract

BACKGROUND

Arginine vasopressin is a neuropeptide produced in the hypothalamus and released by the posterior pituitary gland. In addition to maintaining plasma osmolarity, under hypovolemic or hypotensive conditions, it helps maintain plasma volume through renal water reabsorption and increases systemic vascular tone. Its synthetic analogues are widely used in the intensive care unit as a continuous infusion, in addition to hospital floors as an intravenous or intranasal dose. A limited number of cases of hyponatremia in patients with septic or hemorrhagic shock have been reported previously with vasopressin. We report for the first time a normotensive patient who developed vasopressin-induced hyponatremia.

CASE SUMMARY

A 39-year-old man fell off a forklift and sustained an axial load injury to his cranium. He had no history of previous trauma. Examination was normal except for motor and sensory deficits. The Imagine test showed endplate fracture at C7 and acute traumatic disc at C7 with cortical degeneration. He underwent cervical discectomy and fusion, laminectomy, and posterior instrumented fusion. After intensive care unit admission post-surgery, he developed hyponatremia of 121-124 mEq/L post phenylephrine and vasopressin infusion to maintain blood pressure maintenance. He was evaluated for syndrome of inappropriate secretion of antidiuretic hormone, hypothyroid, adrenal-induced, or diuretic-induced hyponatremia. At the end of extensive evaluation for the underlying cause of hyponatremia, vasopressin was discontinued. He was also put on fluid restriction, given exogenous desmopressin, and a dextrose 5% in water infusion to prevent osmotic demyelination syndrome caused by sodium overcorrection which improved his sodium level to 135 mmol/L.

CONCLUSION

The presentation of vasopressin-induced hyponatremia is uncommon in normotensive patients, and the most difficult aspect of this condition is determining the underlying cause of hyponatremia. Our case illustrates that, considering the vast differential diagnosis of hyponatremia in hospitalized patients, both hospitalists and intensivists should be aware of this serious complication of vasopressin therapy.

Keywords: Hyponatremia; Vasopressin; Normotensive; Therapy; Case report

Core Tip: While hyponatremia can have many causes, vasopressin-induced hyponatremia in normotensive patients is unusual. Since the coronavirus disease 2019 pandemic, vasopressin use has increased in intensive care units across the country, and vasopressin-induced hyponatremia is likely underrated. We have intervened by discontinuing vasopressin, which led to rapid overcorrection of the sodium, and thus required temporary exogenous desmopressin and a dextrose 5% in water infusion. Through his care, the patient's serum sodium returned to normal and he made a full recovery. This makes our case unique.