1764: Extreme Azotemia and Hypernatremia Due to Homemade Formula in a Child With Acute Diarrhea

Introduction: Azotemia and hypernatremia are common electrolyte disturbances in children with diarrheal illness. However, these abnormalities may be significantly worsened by the use of a home-made formula with excessive protein content. This presents a unique challenge in managing serum osmolality, as both hypernatremia and markedly elevated blood urea nitrogen (BUN) contribute to hyperosmolality. Correcting these imbalances requires a delicate balance of free water replacement while minimizing the risk of neurological complications. Description: A 2-year-old male with Rubinstein-Taybi Syndrome, Dandy-Walker malformation, and gastric-tube dependence presented minimally responsive after 2 days of increased stool frequency. At baseline, he is interactive with his caregivers. In the emergency department, he was lethargic and responded only to noxious stimuli. Initial labs revealed sodium (Na) 168mEq/L, glucose 299mg/dL, BUN 184mg/dL, creatinine 0.72mg/dL (BUN/Cr ratio 256), and calculated serum osmolality of 418mOsm/kg. He received 20 mL/kg of normal saline via intraosseous access and Pedialyte via G-tube until central access was obtained. Na subsequently rose to 176mEq/L. In the next 48 hours, IV hydration was carefully titrated with frequent monitoring to prevent rapid correction. Stool PCR returned positive for Norovirus. Further history revealed that due to a lapse in access to commercial formula, the family had been using a homemade mixture of baby food, yogurt, milk, and toddler formula. While caloric and fluid content were adequate, protein intake was calculated at 10.5g/kg/day—markedly excessive. After gradual stabilization of Na, the patient was transitioned to a commercial pediatric peptide formula. At discharge, he was at his neurological baseline with Na 142mEq/L, glucose 98mg/dL BUN 7mg/dL, and Cr 0.35mg/dL. Discussion: Infectious diarrhea can cause electrolyte disturbances, but the addition of excessive protein from improperly formulated feeds can markedly exacerbate hyperosmolality through profound azotemia. This case highlights the importance of recognizing the osmotic burden imposed by elevated BUN in conjunction with hypernatremia. Careful titration of free water is essential to prevent rapid shifts in Na and osmolality, which increase the risk of neurological complications.