Abstract
We report a case of a 20-day-old neonate who presented with severe dehydration, persistent loose stools, and metabolic acidosis. Despite correction of dehydration and bicarbonate deficit, the baby continued to have diarrhea and metabolic acidosis. Further evaluation revealed evidence of primary lactose intolerance and distal renal tubular acidosis (dRTA). The case emphasizes the importance of considering dual pathology in neonates with persistent diarrhea and metabolic acidosis.
Introduction
Persistent neonatal diarrhea associated with metabolic acidosis often raises suspicion of gastrointestinal malabsorption or renal tubular disorders. Early recognition and targeted management are crucial to prevent growth failure and mortality.
Case Presentation
Patient: 20-day-old neonate
Presentation: Loose stools, severe dehydration, metabolic acidosis
Initial ABG: Metabolic acidosis with base deficit of –22, low bicarbonate, normal anion gap
Management: IV fluids, correction of acidosis with bicarbonate → temporary stabilization
However, diarrhea persisted (≈15 episodes/day).
Repeat ABG: Persistent metabolic acidosis
Stool analysis: Reducing substances present
Urinary evaluation: pH ~6.5, urinary anion gap positive, Na⁺ 131, K⁺ 46, Cl⁻ 103
Renin & Aldosterone: Slightly elevated
Diagnosis considered: Primary Lactose Intolerance + Distal RTA
Management
Started on lactose-free formula
Syrup sodium bicarbonate and potassium supplementation initiated
Follow-up ABG: pH corrected, electrolytes normalized
Clinical outcome: Stool frequency reduced, weight gain achieved (3 kg at 1.5 months)
Discussion
Persistent metabolic acidosis despite correction of dehydration suggests underlying renal or gastrointestinal cause.
Presence of reducing substances in stool → Lactose Intolerance
Urine pH >5.5 with positive urinary anion gap in metabolic acidosis → Distal RTA
Dual pathology made management challenging.
Early dietary intervention and alkali therapy resulted in clinical improvement.
Conclusion
This case highlights the importance of considering combined gastrointestinal and renal etiologies in neonates with refractory diarrhea and acidosis. Prompt recognition and management significantly improve outcomes.
References
Rodríguez-Soriano J. Renal tubular acidosis: the clinical entity. J Am Soc Nephrol. 2002;13(8):2160–2170.
Walker-Smith JA. Lactose intolerance in infants and children. J Pediatr Gastroenterol Nutr. 1982;1(2):163–169.
Kliegman RM, St. Geme JW. Nelson Textbook of Pediatrics, 21st Edition. Elsevier; 2020.
