Mysterious hyperkalemia and cardiac arrest in a newborn infant undergoing continuous veno-venous hemofiltration dialysis: question

Excerpt

A 16-days-old girl was transferred to our pediatric intensive care unit (PICU) because of neurological and respiratory deterioration. She had been born after an uneventful pregnancy to Druse parents who were first cousins. She was being fed on breast milk. On day 7 she refused feeding, her cry weakened, and she was hospitalized in another hospital. On admission she was afebrile and had generalized hypotonicity, head lag, areflexia, drooling and ptosis. Findings from sepsis workup and liver and kidney function tests were normal. Her level of consciousness continued to deteriorate, she developed extreme weakness, bradypnea and recurrent apnea and was transferred to our PICU. On admission she required intubation and mechanical ventilation because of extreme bradypnea. On the next day, metabolic workup revealed very high urine and blood levels of leucine, isoleucine and valine, which led to the diagnosis of maple syrup urine disease (MSUD). …