P2.L235: Milky Blood: An Unusual Finding in an Infant with Rectal Bleeding

Introduction: Bleeding per rectum in infancy is a common presenting sign that can often be managed in outpatient settings. Rarely, it may be the first presentation of a life-threatening condition. We report a case of rectal bleeding in an infant presenting with hemodynamic instability and an unexpected finding on initial blood-draw.

Case Description: A 5-week-old infant presented to the emergency department with lethargy and 2 weeks of worsening blood per rectum. She was born at term following an uncomplicated pregnancy and delivery. On presentation she was unstable with tachycardia, tachypnea, and signs of poor perfusion including thready pulses and delayed capillary refill time. Initial blood draws were described as ‘pink and frothy’ and laboratory results including CBC and point-of-care glucose were inconclusive or uninterpretable. She was resuscitated with crystalloids, dextrose, and packed red blood cells. After several hours delay, laboratory investigations returned with triglycerides above a detection limit of 15,664 mg/dL (reference range 53-258 mg/dL). Eventually, with biochemist consult, centrifugation, and manual sample dilution, bloodwork returned revealing significant anemia (5.3 g/dL) and severe hypertriglyceridemia (71,685 mg/dL).

Following resuscitation, she developed respiratory distress requiring continuous positive airway pressure support. She was empirically started on IV pantoprazole and given vitamin K. Initial treatment for hypertriglyceridemia consisted of intravenous insulin and dextrose infusions for 48 hours. Due to on-going hypertriglyceridemia, manual whole blood exchange transfusion was completed (exchange volume of 100 mL/kg). Aliquots were ‘strawberry milkshake’ coloured and immediately showed separation of lipid components. Triglyceride levels decreased significantly following exchange (1,947 mg/dL). Trophic feeds of medium chain triglyceride formula were initiated 2 days later and triglyceride levels continued to downtrend to mildly elevated levels (885-1,328 mg/dL). GI bleeding resolved within 5 days of presentation. Familial chylomicronemia genetic panel confirmed autosomal recessive lipoprotein lipase (LPL) deficiency.

Discussion: LPL deficiency is a rare metabolic disorder causing severe hypertriglyceridemia with a prevalence of 1:1,000,000, often presenting in infancy. GI bleeding is thought to occur due to hyperviscous blood leading to impaired perfusion and bowel ischemia. Acute management includes insulin which induces LPL activity to decrease serum triglyceride levels if there is residual LPL function. Plasmapheresis can directly remove lipoproteins from the blood, while whole blood exchange replaces lipemic blood with donor blood. This infant was unsuitable for plasmapheresis as their total blood volume was too small, so whole blood exchange was completed with near normalization of hypertriglyceridemia.

Conclusion: LPL deficiency is a rare disorder with heterogenous presentations. We report an infant with LPL deficiency who had a severe presentation requiring exchange transfusion. Despite this, neurologic, pulmonary, hepatic, and renal end-organ function was preserved. This case highlights the heterogeneous presentations of metabolic disorders and the need for broad differentials when encountering the acutely unwell child.