Frequency and Types of Hyponatremia in Stroke Patients Admitted in a Referral Neuroscience Institute of Dhaka

Background: Hyponatremia is a common electrolyte abnormality in acute stroke patients and may be related to variable etiology. Objective: To observe the frequency and types of hyponatremia in hospitalized acute stroke patients. Materials and methods: This cross-sectional study, carried out in a referral neuroscience institute of Dhaka during February to November 2017, included 209 patients admitted with acute stroke (65 ischemic, age 61.5±13.3 years, M/F: 45/20; 144 hemorrhagic, age 59.2±13.1 years, M/F: 80/64). The clinical and laboratory values on admission were recorded. Those having hyponatremia (serum sodium <135 mmol/L) on admission were evaluated by clinical features (history of vomiting or diarrhoea, volume status, urine output) and laboratory parameters (urine osmolality, urine sodium, plasma osmolality, blood urea, hematocrit) to determine the types of hyponatremia. Results: Four patients died before the serum could be sent for electrolytes. Among the rest, 36 (17.6%) had hyponatremia on admission. Serum sodium level was <125 mmol/L in 7 (19.4%) and 125-134 mmol/L in rest of the patients having hyponatremia (29; 80.6%). The frequency of hyponatremia was similar in ischemic and hemorrhagic stroke (17.2% vs. 17.7%, p=0.925). Syndrome of inappropriate antidiuresis (SIAD) was most frequent cause of hyponatremia (50.0%), followed by cerebral salt wasting (CSW; 30.6%). The rest had either hyponatremia related to gastrointestinal (GI) fluid loss (2.8%) or died before a cause of hyponatremia could be ascertained (11.1%). There was no significant difference of age, gender, NIHSS score and GCS score on admission as well as in hospital stay and in-hospital mortality between patients with or without hyponatremia (p=ns for all). Frequency of CSW was relatively higher in hemorrhagic stroke (hemorrhagic vs. ischemic: 32.0% vs. 27.3%) and SIAD in ischemic stroke (hemorrhagic vs. ischemic: 40.0% vs. 72.7%) but did not reach level of statistical significance. Conclusion: Frequency of hyponatremia seems remarkable in hospitalized acute stroke patients, SIAD and CSW being the most frequent cause.