TPN and hyperbilirubinemia

Q: Total parenteral nutrition (TPN) tends to cause? (select one)

A) Conjugated hyperbilirubinemia

B) Unconjugated hyperbilirubinemia 

  

Answer: A

The mere recognition of conjugated (direct) and unconjugated (indirect) hyperbilirubinemia may help to determine the actual underlying pathophysiology. A major underlying cause of unconjugated hyperbilirubinemia (and often unrecognized) in ICU is TPN. Most of the time, in ICU complex patients, there are two or even more causes of direct and/or indirect hyperbilirubinemia. 

The major causes of conjugated hyperbilirubinemia in ICU are "inside liver-based" - and can be remembered as direct - 

• Hepatitis and steatohepatitis 
• Primary biliary cholangitis 
• Drugs
• Toxins 
• Ischemia 
• Infiltration 
• Inherited disorders 
• Total parenteral nutrition 
• Postoperative jaundice 
• Intrahepatic cholestasis of pregnancy 
• End-stage liver disease 
• Post-organ transplant

In contrast, the causes of unconjugated hyperbilirubinemia occur outside the liver (indirect) like

• Hemolysis 
• Dyserythropoiesis 
• Stress situation (most common is sepsis) (increased production of bilirubin)
• Impaired bilirubin uptake or conjugation

#hepatology

References:

1. Tripathi N, Jialal I. Conjugated Hyperbilirubinemia. 2021 Sep 28. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 32965843. 

2. Singh A, Koritala T, Jialal I. Unconjugated Hyperbilirubinemia. 2021 Dec 6. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 31747203.