Cerebral Salt Wasting Is the Most Common Cause of Hyponatremia in Stroke

The study aimed to evaluate the frequency, severity, and causes of hyponatremia in stroke and its influence on outcome.

Consecutive computed tomography- or magnetic resonance imaging-proven stroke patients within 7 days of stroke were included. Severity of stroke was assessed using the National Institute of Health Stroke Scale and consciousness using the Glasgow Coma Scale. Hyponatremia was defined if 2 consecutive serum sodium levels were <135 mEq/L and hypernatremia if >145 mEq/L. Causes of hyponatremia, such as cerebral salt wasting (CSW) and syndrome of inappropriate secretion of antidiuretic hormone (SIADH), were based on predefined criteria. Patients with CSW were managed by salt supplementation and normal saline, and fludrocortisone was used in refractory cases. In SIADH, fluid was restricted. Outcome on discharge was defined using the modified Rankin Scale (mRS).

One hundred patients with stroke were included: 47% had ischemic stroke and 53% had intracerebral hemorrhage. Forty-three percent of the patients had hyponatremia, 6% had hypernatremia, and 4% had both. Hyponatremia was due to CSW in 19 (44.2%), SIADH in 3 (7%), miscellaneous causes in 14 (32.6%), and indeterminate in 7 (16.3%) patients. Duration of hospitalization was the independent predictor of hyponatremia and CSW. Fourteen patients died, whereas 15 had good outcome (mRS score of ≤2) and 71 had poor outcome (mRS score of 3-5). Hypernatremia was associated with high mortality compared with eunatremia and hyponatremia.

Hyponatremia occurred in 43% of stroke patients. CSW was the most common cause of hyponatremia. Hyponatremia, however, was not related to death or disability.