From the Guidelines
Decreased albumin levels and prolonged prothrombin time primarily reflect impaired synthetic function of the liver in patients with liver disease. The liver is responsible for producing numerous proteins essential for normal physiological processes, including albumin and clotting factors, as stated in the guidelines on the management of abnormal liver blood tests 1. When liver cells are damaged or dysfunctional, their ability to synthesize these proteins becomes compromised. Albumin, the most abundant protein in blood plasma, is exclusively produced by the liver and maintains oncotic pressure while transporting various substances throughout the body, as noted in the guidelines 1. A decline in serum albumin levels indicates chronic liver dysfunction, as albumin has a relatively long half-life of about 20 days. Prothrombin time measures the function of the extrinsic and common coagulation pathways, which depend on vitamin K-dependent clotting factors (II, VII, IX, X) produced by the liver, and is used to measure liver function, as confirmed by a prolonged PT or INR 1. These clotting factors have much shorter half-lives than albumin, making prothrombin time a more sensitive indicator of acute changes in liver synthetic function.
Some key points to consider in this context include:
- Albumin concentrations are reduced in many clinical situations, including sepsis, systemic inflammatory disorders, nephrotic syndrome, malabsorption, and gastrointestinal protein loss, as mentioned in the guidelines 1.
- A prolonged PT/INR can indicate either acute or chronic liver dysfunction but can also be caused by vitamin K deficiency, as seen in fat malabsorption and chronic cholestasis, highlighting the need for a comprehensive assessment 1.
- The liver's synthetic function is critical for producing proteins essential for blood clotting, and impairments in this function can lead to coagulopathy, as discussed in the guidelines on the management of abnormal liver blood tests 1.
Overall, the combination of decreased albumin levels and prolonged prothrombin time provides valuable information about the liver's capacity to perform its protein synthesis role and is commonly used to assess the severity of liver disease and prognosis in clinical settings, in line with the guidelines 1.
From the Research
Liver Function Reflection
The laboratory results of a middle-aged patient with liver disease, showing decreased levels of albumin and prolonged prothrombin time, primarily reflect the liver's synthetic function.
- The liver's ability to synthesize proteins such as albumin and clotting factors is impaired in liver disease, leading to decreased levels of these proteins in the blood 2, 3.
- Albumin is a critical plasma protein produced by the liver, and its decreased levels in liver disease are associated with impaired liver function 2, 4.
- Prolonged prothrombin time is also a reflection of the liver's impaired synthetic function, as the liver is responsible for producing clotting factors that are necessary for blood coagulation 5, 6.
- The liver's synthetic function is closely related to its cellular mass and effective hepatic blood flow, and decreased albumin levels and prolonged prothrombin time are highly correlated with these parameters 3.
Synthetic Function
The synthetic function of the liver is responsible for producing a wide range of proteins, including albumin, clotting factors, and other plasma proteins.
- In liver disease, the synthetic function of the liver is impaired, leading to decreased production of these proteins 2, 6.
- The decreased levels of albumin and clotting factors in liver disease are a reflection of the liver's impaired synthetic function, and can be used as markers of liver dysfunction 5, 3.
- The liver's synthetic function is closely related to its cellular mass and effective hepatic blood flow, and decreased synthetic function is associated with decreased liver cell mass and impaired hepatic blood flow 3.