Clinical Utility of Free 25OH Vitamin D during Liver disease
In patients with liver failure such as cirrhosis, hepatitis A, B, C, D, and E, Epstein Barr virus (infectious mononucleosis), non-alcoholic fatty liver disease, the levels of 25OH Vitamin D can be low due to impaired synthesis. Liver disease could also lead to impaired absorption of Vitamin D, which is possibly connected to impaired bile acid production or gut edema associated with portal hypertension.
Low vitamin D levels and bone disease are well-recognized complications of “cholestatic” liver disease, which decreases the production or flow of bile. More recently, studies have confirmed low Vitamin D levels in noncholestatic liver disease.
Many post-transplant patients are also prone to accelerated bone loss, which could be worsened by Vitamin D deficiency. Dangerously low levels of Vitamin D may also increase some side effects of interferon therapy, such as muscle aches. There are some reports of hepatitis C patients with Vitamin D deficiency responding poorly to interferon therapy.
Therefore it is recommended that all hepatologists should monitor Vitamin D levels and treat deficient patients.
Due to a decrease in the concentration of the Vitamin D Binding Protein during liver failure the measurement of total 25OH Vitamin D is no longer a good representation of the concentration of the free 25OH Vitamin D.
The total 25OH Vitamin D test underestimates the free fraction, with the risk of Vitamin D status misclassification.
Recent research has shown that the measurement of free 25OH Vitamin D during liver disease seems to be a better marker of Vitamin D deficiency than the current total 25OH Vitamin D test. Additional clinical studies are currently initiated in order to bring more evidences.