From the Guidelines
The liver's synthetic function is best assessed through measurements of albumin and prothrombin time, as these parameters are direct markers of hepatocellular synthetic capacity. The liver performs numerous vital synthetic functions essential for maintaining homeostasis, including the production of plasma proteins, bile acids, cholesterol, and lipoproteins, as well as glucose metabolism and detoxification of ammonia 1. Impaired liver synthetic function can lead to hypoalbuminemia, coagulopathy, hypoglycemia, and other metabolic disturbances.
Key Markers of Liver Synthetic Function
- Albumin: a protein produced only in the liver, essential for maintaining oncotic pressure and transporting substances 1
- Prothrombin time (PT) and international normalized ratio (INR): assessments of blood clotting that measure liver function, as the underlying protein clotting factors are made in the liver 1
- Platelets: a reduction in platelets, termed thrombocytopenia, is a common haematological abnormality found in patients with chronic liver disease and is an indicator of advanced disease 1
Assessment and Monitoring
Regular assessment of liver synthetic function is crucial, especially in patients with underlying liver diseases. The American College of Gastroenterology recommends monitoring liver function tests, including albumin, PT, and INR, at least every 6 months to detect progression of liver disease 1. Additionally, maintaining adequate nutrition, avoiding hepatotoxic substances, and treating underlying liver diseases are essential for preserving these critical synthetic functions. In patients with hepatic synthetic dysfunction-induced coagulation abnormalities, routine correction of thrombocytopenia and coagulopathy is not recommended before low-risk therapeutic procedures 1.
From the FDA Drug Label
Vitamin K1 Injection (Phytonadione Injectable Emulsion, USP) aqueous dispersion of vitamin K1 for parenteral injection, possesses the same type and degree of activity as does naturally-occurring vitamin K, which is necessary for the production via the liver of active prothromxin (factor II), proconvertin (factor VII), plasma thromboplastin component (factor IX), and Stuart factor (factor X). The status of liver synthetic function cannot be directly determined from the information provided in the drug label.
- The label discusses the role of vitamin K in the production of coagulation factors, but it does not provide information on how to assess liver synthetic function. 2
From the Research
Liver Synthetic Function
The liver's synthetic function can be assessed through various parameters, including albumin levels and prothrombin time-international normalized ratio (PT-INR) [(3,4,5)].
- Albumin is a key protein synthesized by the liver, and its levels can indicate liver function [(3,4,5,6)].
- The PT-INR to albumin ratio (PTAR score) has been shown to be a useful tool in predicting mortality in patients with cirrhosis and sepsis [(3,4)].
- A study found that the PTAR score was associated with in-hospital mortality rates, with higher scores indicating a higher risk of mortality 3.
- Another study validated the usefulness of the PTAR score in predicting mortality in patients with sepsis, showing that it had a moderate discrimination capacity 4.
Prognostic Value of Liver Synthetic Function
The prognostic value of liver synthetic function has been investigated in various studies [(7,5,6)].
- A study found that serum ferritin level and PTAR score increased in proportion to the severity of liver disease and were associated with poor prognosis 5.
- Impaired albumin function has been reported in various liver diseases, including non-alcoholic fatty liver disease, viral hepatitis, cirrhosis, and liver failure, and is associated with disease severity and prognosis 6.
- Albumin function may represent a novel biomarker of early impairment in liver function, as it can be affected by post-translational modifications that alter its biological activity 6.
Assessment of Liver Synthetic Function
The assessment of liver synthetic function can be done through various tests, including 7:
- Liver function tests, such as prothrombin time/international normalized ratio
- Serum and ultrasound-based screening tests, such as the aspartate transaminase to platelet ratio index score and Fibrosis 4 score
- Non-invasive tests, such as transient elastography, can be useful in identifying patients with no to minimal fibrosis or advanced fibrosis 7.