Sodium Bicarbonate Toxicity: An Unusual Yet Potential Cause of Severe Metabolic Alkalosis

Sodium bicarbonate, commonly known as baking soda, is present in various over-the-counter medications sold to the general public, including for the treatment of gastrointestinal symptoms such as nausea and dyspepsia. Less well known to the public are the severe complications associated with these treatments and their overuse, which can lead to significant toxicity, including metabolic alkalosis and associated electrolyte imbalances, further perpetuating or even worsening the acid-base disorder. In this case report, we present a 45-year-old woman with a history of locally invasive breast cancer, who underwent primary chemotherapy and radiotherapy with remission. She presented to the Emergency Department with nausea, vomiting, and abdominal discomfort that began one month earlier, along with asthenia and weight loss predating these symptoms. She had begun taking over-the-counter medications recommended by a local herbalist, some of which contained sodium bicarbonate or calcium carbonate. The patient was hypotensive, vomiting, and showed signs of dehydration. Her blood gas analysis revealed severe metabolic alkalosis with significant hypokalemia and hypochloremia. Prompt treatment was initiated, and the patient was admitted to the Intermediate Care Unit. Following an exhaustive diagnostic workup for her initial symptoms, pyloric stenosis caused by a locally advanced gastric neoformation was identified and later confirmed to be carcinoma. The patient was referred to the Oncology Group, where primary chemotherapy was recommended and initiated; however, the patient ultimately succumbed to her illness. In conclusion, recognizing and understanding the mechanisms underlying the generation and maintenance of metabolic alkalosis, along with its causes and a thorough review of the patient's medical history, are crucial for clinicians to ensure proper and timely intervention and correction of the acid-base disorder.