Question 1

Q: A 10-day-old infant with MSUD is admitted with lethargy, poor feeding, and plasma leucine of 2000 μmol/L (normal <200). Despite BCAA-free formula, the infant's condition worsens with encephalopathy. The neonatology team proposes hemodialysis, while the genetics team suggests continuing medical management with high-calorie IV fluids. The family is concerned about invasive procedures. Evaluate the optimal management strategy.

Immediate hemodialysis to rapidly lower leucine levels. ***Immediate hemodialysis to rapidly lower leucine levels*** - **Extracorporeal detoxification** via hemodialysis is the most effective method to rapidly lower neurotoxic **leucine** levels when they exceed 1000 μmol/L and cause **encephalopathy**. - Rapid clearance is critical to prevent **cerebral edema** and permanent **neurological sequelae** in neonates with acute MSUD crisis. *Continue medical management and reassess in 24 hours* - Delaying definitive treatment for 24 hours in a symptomatic infant with leucine at 2000 μmol/L is dangerous and increases the risk of **brain herniation**. - Standard medical management including **BCAA-free formula** cannot clear existing toxic metabolites fast enough to reverse acute **metabolic encephalopathy**. *Start peritoneal dialysis as less invasive alternative* - **Peritoneal dialysis** is significantly slower and less efficient than hemodialysis at removing branched-chain amino acids like **leucine**. - It is not recommended as first-line therapy in a critical **metabolic emergency** when hemodialysis or continuous venovenous hemodiafiltration (CVVH) is available. *Exchange transfusion with albumin solutions* - **Exchange transfusion** is largely ineffective for MSUD because it only removes toxins from the intravascular space and does not reach the larger **intracellular pool**. - This method has been superseded by modern renal replacement therapies which offer superior **clearance rates** for small molecules. *High-dose thiamine trial before considering dialysis* - Only a small subset of MSUD patients are **thiamine-responsive**, and a trial should never delay **life-saving dialysis** in an unstable patient. - **Thiamine** acts as a cofactor for the deficient enzyme complex but will not provide the immediate **detoxification** required for a level of 2000 μmol/L.

Question

A 10-day-old infant with MSUD is admitted with lethargy, poor feeding, and plasma leucine of 2000 μmol/L (normal <200). Despite BCAA-free formula, the infant's condition worsens with encephalopathy. The neonatology team proposes hemodialysis, while the genetics team suggests continuing medical management with high-calorie IV fluids. The family is concerned about invasive procedures. Evaluate the optimal management strategy.

Accepted Answer

Immediate hemodialysis to rapidly lower leucine levels

Answer

High-dose thiamine trial before considering dialysis

Answer

Continue medical management and reassess in 24 hours

Answer

Exchange transfusion with albumin solutions

Answer

Start peritoneal dialysis as less invasive alternative

Amino acid metabolism and disorders — MCQs

Amino acid metabolism and disorders — MCQs

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