A Rare Triad of Type 1 Distal Renal Tubular Acidosis, Cryptogenic Multifocal Ulcerous Stenosing Enteritis, and Superior Mesenteric Artery Syndrome in a Young Adult

Recurrent hypokalaemia and iron-deficiency anaemia in a young adult should prompt evaluation for uncommon renal and gastrointestinal disorders. The coexistence of distal renal tubular acidosis (dRTA), cryptogenic multifocal ulcerous stenosing enteritis (CMUSE), and superior mesenteric artery (SMA) syndrome is exceptionally rare. A woman in her 30s presented in 2019 with profound hypokalaemia and cardiac arrest secondary to possible dRTA. Biochemistry confirmed non-anion gap metabolic acidosis with inappropriate renal potassium loss. Despite supplementation, she later developed severe iron-deficiency anaemia and underwent small-bowel resection for capsule retention; histology confirmed CMUSE. Subsequent weight loss and malnutrition led to radiological evidence of SMA syndrome. She experienced recurrent admissions for electrolyte crises, requiring long-term intravenous replacement via a peripherally inserted central catheter and multidisciplinary input from nephrology, gastroenterology, and endocrinology. This case illustrates the cumulative burden and interdependence of multiple rare disorders within one patient, emphasising the need for persistent diagnostic review, multidisciplinary care, and awareness of atypical disease combinations in young adults with refractory electrolyte and nutritional abnormalities.