Extreme Metabolic Alkalosis Caused by Temporary Jejunostomy—A Case Report and Physiopathological Insights

<b>Background and Clinical Significance</b>: Metabolic alkalosis is the most common acid-base disturbance in hospitalized and critically ill patients, with extreme alkalemia (pH > 7.65) linked to mortality rates exceeding 80%. Jejunostomy-related intestinal losses can lead to severe hypochloremic metabolic alkalosis, a rare but life-threatening condition. This case report highlights the clinical presentation, diagnostic approach, physiopathology, management, and outcome of a patient with extreme metabolic alkalosis induced by a temporary jejunostomy. <b>Case Presentation</b>: We report the case of a 72-year-old female who presented with severe alkalemia, seizures, and signs of profound dehydration following extensive enteral resection with end-jejunostomy. Serial arterial blood gas and serum electrolyte monitoring guided treatment, prompting the initiation of an aggressive chloride-based rehydration protocol. Concurrent evaluations revealed renal impairment and an intercurrent infection. Initial tests revealed extreme metabolic alkalosis (pH 7.757, HCO₃^- 72.7 mmol/L) with severe hypochloremia, hypokalemia, and acute kidney injury. Administration of approximately 5 L of isotonic saline with added potassium chloride over the first 6 h led to rapid improvement in pH to near-normal levels. Over the following six days, continued electrolyte correction restored physiological acid-base balance and renal function. After achieving metabolic stabilization, the jejunostomy was surgically reversed. <b>Conclusions</b>: Extreme metabolic alkalosis secondary to jejunostomy is rare but potentially fatal. Prompt recognition of chloride-responsive alkalosis and rapid initiation of aggressive volume and electrolyte replacement are essential for survival. Definitive management requires addressing the underlying cause, such as restoration of gastrointestinal continuity, to prevent recurrence.