In addition, the liver functions in the storage, meta bolism, and homeostasis of iron. It synthesizes almost all of the proteins involved in iron transport and metabolism, including transferrin, haptoglobin, and hemopexin. Transferrin is a plasma iron-transport protein. Haptoglobin binds to free hemoglobin in the plasma, from which the entire complex is removed by the liver to preserve iron. Hemopexin is involved in the transport of free heme in the blood. Iron is stored within the hepatocyte cytoplasm in the form of ferritin or may be converted to hemosiderin granules. Recent studies indicate that hepatocytes are the major sites of long-term storage of iron. Iron overload (as in multiple blood transfusions) may lead to hemochromatosis, a form of liver damage characterized by excessive amounts of hemosiderin in hepatocytes.
The liver degrades drugs and toxins.
Hepatocytes are involved in degradation of drugs, toxins, and other proteins foreign to the body (xenobiotics).
Many drugs and toxins are not hydrophilic; therefore, they cannot be eliminated effectively from the circulation by the kidneys. The liver converts these substances into more soluble forms. This process is performed by the hepatocytes in two phases:  Phase I (oxidation) includes hydroxylation (adding an OOH group) and carboxylation (adding a OCOOH group) to a foreign compound. This phase is performed in the hepatocyte smooth endoplasmic reticulum (sER) and mitochondria. It involves a series of biochemical reactions with proteins collectively named cytochrome P450.
 Phase II (conjugation) includes conjugation with glucuronic acid, glycine, or taurine. This process makes the product of phase I even more water soluble so that it can be easily removed by the kidney.
The liver is involved in many other important metabolic pathways.
The liver is important in carbohydrate metabolism as it maintains an adequate supply of nutrients for cell processes. In glucose metabolism, the liver phosphorylates absorbed glucose from the gastrointestinal tract to glucose-6phosphate. Depending on energy requirements, glucose-6-phosphate is either stored in the liver in the form of glycogen or used in the glycolytic pathways. During fasting, glycogen is broken down by the process of glycogenolysis, and glucose is released into the bloodstream. In addition, the liver functions in lipid metabolism. Fatty acids derived from plasma are consumed by hepatocytes using -oxidation to provide energy. The liver also produces ketone bodies that are used as a fuel by other organs (the liver cannot use them as an energy source). The involvement in cholesterol metabolism (synthesis and uptake from the blood) is also an important function of the liver. Cholesterol is used in the formation of bile salts, synthesis of VLDLs, and biosynthesis of organelles. The liver synthesizes most of the urea in the body from ammonium ions derived from protein and nucleic acid degradation. Finally, the liver is involved in the synthesis and conversion of nonessential amino acids.
Bile production is an exocrine function of the liver.