Welcome to PICU Doc On Call, A Podcast Dedicated to Current and Aspiring Intensivists. I'm Pradip Kamat coming to you from Children’s Healthcare of Atlanta/Emory University School of Medicine and I'm Rahul Damania from Cleveland Clinic Children’s Hospital and we are two Pediatric ICU physicians passionate about all things MED-ED in the PICU. PICU Doc on Call focuses on interesting PICU cases & management in the acute care pediatric setting so let’s get into our episode: Welcome to our Episode of a 4-day-old with jaundice and vomiting. Here's the case presented by Rahul: A full-term 4-day-old boy presents to the ED after recently being discharged from the newborn nursery. Per mom, the patient "look yellow" and was having difficulty with feeding. The mother states that the patient would be increasingly sleepy, and will only latch to the breast for five minutes. The patient has been having decreased wet diapers, and the stool is loose and non-bloody. Mother was concerned today as the child continue to look yellow, especially in the eyes, had four episodes of vomiting, and overall was acting lethargic. The patient presented to the emergency room afebrile, tachypneic, and tachycardic. The patient was noted to have initial serum glucose of 70. As the patient was increasingly dehydrated, laboratory testing was difficult to obtain. The infant was fussy for the caregivers. The patient was resuscitated with 2 x 10 per kilo boluses and responded well. Point of care ultrasound noted normal four-chamber cardiac anatomy and squeeze. Given the instability of the patient, a RAM cannula was initiated, and the patient presented to the PICU. To summarize key elements from this case, this 4-day-old infant has: an acute presentation of jaundice and poor feedingProminent GI symptoms and dehydrationA sepsis-like presentation with hemodynamic instability responsive to fluidsAll of which brings up a concern for inborn error of metabolism, likely galactosemia.This episode will be organized…Clinical PresentationLaboratory Findings & BiochemistryManagement of Galactosemia Rahul, let's start with a short multiple choice question: Of the following biochemical enzymes, which of the following is deficient in classic galactosemia?A. UDP Glucoronyl TransferaseB. Aldolase BC. Galactose 1 Uridyl TransferaseD. Galactokinase The correct answer is C. Galactose 1 Uridyl Transferase aka GALT. Classic galactosemia is caused by a complete deficiency of galactose-1-phosphate uridyl transferase (GALT). We should contrast this with galactokinase deficiency. These two present quite differently — GALT deficiency presents like our patient with jaundice, vomiting, hepatomegaly, renal dysfunction, and sepsis. Galactokinase deficiency has less of systemic symptoms and these patients similar to GALT deficiency have cataracts that are usually bilateral and resolved with dietary therapy. To go through our other answer choices, remember that Aldolase B is the rate-limiting enzyme in fructose metabolism, thus a deficiency in this enzyme would cause hereditary fructose intolerance. With this lead in question, let’s pivot into the biochemistry of galactose and review key lab findings in our patient with galactosemia. Rahul, can you give us a quick summary of how galactose is metabolized in our body? Galactose is a sugar found primarily in human milk and milk products as part of the disaccharide lactose. Lactose is hydrolyzed to glucose and galactose by the intestinal enzyme lactase. The galactose then is converted to glucose for use as an energy source, however it needs a series of reactions: Galactokinase → which catalyzes the rxn galactose to galactose 1 PO4Our rate limiting enzyme Galactose-1-phosphate uridyl transferase