Ms. Thoa was admitted to the hospital with reduced consciousness and rapid breathing. Dr. Ha Viet Ngoc, from the Intensive Care and Anti-poisoning Department at Tam Anh Hanoi General Hospital, diagnosed her with respiratory failure, hypoxemia, and a lower respiratory tract infection.

An MRI scan of her brain revealed an acute infarction in the left cerebellar hemisphere, along with old hemorrhages in both cerebral and cerebellar hemispheres. She also presented with moderate hyponatremia. Doctors determined this electrolyte imbalance could worsen her existing brain damage. Severely low sodium levels can lead to confusion, reduced consciousness, seizures, or coma.

The medical team consulted and considered two potential diagnoses: cerebral salt wasting syndrome (CSW) or syndrome of inappropriate antidiuretic hormone secretion (SIADH). Both syndromes share similar manifestations and can occur in patients with neurological conditions.

According to Dr. Ngoc, there is currently no unified diagnostic standard for cerebral salt wasting syndrome. Instead of relying on a single test, the team had to monitor the patient's progress, including urine output, sodium loss through urine, body fluid status, and changes in sodium levels after each treatment step.

Ms. Thoa receiving special care in the Intensive Care Department. *Photo: Tam Anh General Hospital*

Initially, Ms. Thoa received fluid replacement and an intravenous infusion of 3% sodium chloride solution, which increased her blood sodium concentration to 134 mmol/L. However, hyponatremia recurred once the infusion was stopped.

The patient's urine output exceeded 1.8 liters daily, accompanied by significant sodium loss through urine, despite low blood sodium. This led doctors to suspect the body was losing salt and water via the kidneys, rather than just experiencing hyponatremia due to fluid retention. After comparing with medical literature criteria and ruling out other causes, the team concluded she had cerebral salt wasting syndrome. Consequently, treatment was adjusted to replace the lost salt and fluids, while also administering medication to help the kidneys retain sodium. Her sodium levels subsequently became more stable. Concurrently, Ms. Thoa received treatment for acute respiratory issues, infection, and brain damage.

After one week of treatment, Ms. Thoa's blood sodium levels were controlled, her health stabilized, and she was discharged. Dr. Ngoc emphasized that hyponatremia in patients can cause brain damage, highlighting the importance of evaluating the underlying cause rather than simply focusing on increasing sodium levels.

Cerebral salt wasting syndrome leads to the body losing both sodium and water, necessitating replacement of lost salt and fluids. In contrast, syndrome of inappropriate antidiuretic hormone secretion causes the body to retain water, diluting blood sodium; treatment for SIADH typically prioritizes restricting fluid intake. According to Dr. Ngoc, accurate differential diagnosis is crucial because misidentifying the cause can lead to ineffective treatment and an increased risk of neurological complications.

By Hieu Nguyen